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  • 1. Abbas, Sk Jahir
    et al.
    Ramacharyulu, P. V. R. K.
    Lo, Hsin-Hsi
    Ali, Sk Imran
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ke, Shyue-Chu
    A catalytic approach to synthesis of PLP analogs and other environmental protocols in a single handed CaO/TiO2 green nanoparticle2017In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 210, p. 276-289Article in journal (Refereed)
    Abstract [en]

    As our precursory stage we have focus straight forward on clean catalytic approach for the production of C3 substituted pyridoxal-5 '-phosphate analogues of vitamin B6, and other environmental protocols like photocatalytic activity, green fossil fuels and c-c coupling using efficient biocompatible eggshell related unrivalled materials which show versatility of the catalytic effect on different inorganic support. The eggshell immobilized nanoparticles have encouraging relevance in creation of new molecules and can advantageously be studied by various spectroscopic, thermal and elemental analyses like powder X-ray diffraction (XRD), Raman spectroscopy, UV-vis, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. The elucidate nature of nanoparticles offer: more active site acts as lewis acid, vacancies on the catalyst surface and good to better yield of C3 substituted deoxy and 2-nor deoxy coenzyme pyridoxine (PN), coupling products propargylamines (PA), photo degrading enhancement of MB and nucleophilic substituted fatty acid (BD). This enzyme cofactor explore molecular synthons to synthetic equivalent: 3-deoxy and 2-nor-3-deoxy pyridoxal (PL), pyridoxal oxime (P0), pyridoxamine (PM) and mono phosphate derivative of 3-deoxyPM, 3-deoxyPL respectively and chemistry of selective oxidation and schiff base mechanism was studied and complemented through combined experimental and theoretical molecular orbital calculation consequently. The heterogeneous catalyst has strong selective ability towards selective reducing pyridine diester, bioactive intermediates substances and holds vast potential towards separation for the photogenerated electron-hole pairs and renewable, nontoxic, biodegradable green fossil fuels. The catalyst including environmental concern is reapplicable and strong impressive that can unfold the space of worthy metal component widely and facilitate the scope to take a vital role in different fileds like catalysis, biochemistry, nanoscience, energy and materials science.

  • 2. Abd El-Hakim, Abou El Fettouh Abd El Moneim
    et al.
    Haroun, Ahmed Abd Allah
    Rabie, Abdel Gawad Mohamed
    Ali, Gomaa Abdelgawad Mohammed
    Abdelrahim, Mohamed Yahia Marei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Helwan University, Egypt.
    Improving the mechanical and thermal properties of chlorinated poly(vinyl chloride) by incorporating modified CaCO3 nanoparticles as a filler2019In: Turkish journal of chemistry, ISSN 1300-0527, E-ISSN 1303-6130, Vol. 43, no 3, p. 750-759Article in journal (Refereed)
    Abstract [en]

    Chlorinated poly(vinyl chloride) (CPVC)/calcium carbonate nanocomposites were successfully prepared by the incorporation of calcium carbonate (CaCO3) nanoparticles into the CPVC matrix. The compatibility between the two phases was obtained by surface modification of the CaCO3 nanoparticles with stearic acid, leading to improved material performance. The effects of the addition of different amounts of CaCO3 nanoparticles to the CPVC on the thermal, mechanical, and morphological characteristics of the CPVC/CaCO3 nanocomposites were investigated. The thermal stability of the CPVC/CaCO3 nanocomposites was evaluated by thermogravimetric analysis and differential scanning calorimetry. In addition, the surface texture of the CPVC and the dispersion of the CaCO3 were evaluated using scanning electron microscopy. Important enhancements in the thermal and mechanical properties of the modified CPVC/CaCO3 nanocomposites were obtained by incorporating different amounts (2.00%, 3.75%, and 5.75%) of surface-modified CaCO3 nanoparticles within the CPVC polymer matrix. The results reveal that 3.75% of CaCO3 was the optimum amount, where the CPVC/CaCO3 nanocomposite shows the highest impact strength, the highest tensile strength, the highest thermal stability, and the lowest elongation percentage. Replacement of the commercial impact modifier used in industry with the prepared surface-modified CaCO3 nanoparticles for the development of CPVC was successfully achieved.

  • 3.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Assiut University, Egypt.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cellulose-Based Materials for Water Remediation: Adsorption, Catalysis, and Antifouling2021In: Frontiers in Chemical Engineering, E-ISSN 2673-2718, Vol. 3, article id 790314Article, review/survey (Refereed)
    Abstract [en]

    Cellulose-based materials have been advanced technologies that used in water remediation. They exhibit several advantages being the most abundant biopolymer in nature, high biocompatibility, and contain several functional groups. Cellulose can be prepared in several derivatives including nanomaterials such as cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibrils (TOCNF). The presence of functional groups such as carboxylic and hydroxyls groups can be modified or grafted with organic moieties offering extra functional groups customizing for specific applications. These functional groups ensure the capability of cellulose biopolymers to be modified with nanoparticles such as metal-organic frameworks (MOFs), graphene oxide (GO), silver (Ag) nanoparticles, and zinc oxide (ZnO) nanoparticles. Thus, they can be applied for water remediation via removing water pollutants including heavy metal ions, organic dyes, drugs, and microbial species. Cellulose-based materials can be also used for removing microorganisms being active as membranes or antibacterial agents. They can proceed into various forms such as membranes, sheets, papers, foams, aerogels, and filters. This review summarized the applications of cellulose-based materials for water remediation via methods such as adsorption, catalysis, and antifouling. The high performance of cellulose-based materials as well as their simple processing methods ensure the high potential for water remediation.

     

  • 4.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Assiut University, Egypt.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cellulose-zeolitic imidazolate frameworks (CelloZIFs) for multifunctional environmental remediation: Adsorption and catalytic degradation2021In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 426, article id 131733Article in journal (Refereed)
    Abstract [en]

    The crystal growth of zeolitic imidazolate frameworks (ZIFs) on biopolymers such as cellulose is a promising method for obtaining hybrid materials that combinenatural and synthetic materials. Cellulose derivative viz. 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO)-mediated oxidized nanocellulose (TOCNF) was used to modulate the crystal growth of ZIF-8 (denoted as CelloZIF-8) and ZIF-L (CelloZIF-L). The synthesis procedure occurred in water at room temperature with and without NaOH. The reaction parameters such as the sequence of the chemical's addition and reactant molar ratio were investigated. The phases formed during the crystal growth were monitored. The data analysis ensured the presence of zinc hydroxide nitrate nanosheets modified TOCNF during the crystallization of CelloZIFs. These phases were converted to pure phases ofCelloZIF-8 and CelloZIF-L. The resultant CelloZIFs materials were used for the adsorption ofcarbon dioxide (CO2), metal ions, and dyes. The materials exhibited high selectivity with reasonable efficiency (100%) toward the adsorption of anionic dyes such as methyl blue (MeB). They can also be used as a catalyst for dye degradation via hydrogenation with an efficiency of 100%. CelloZIF crystals can be loaded into a filter paper for simple, fast, and selective adsorption of MeB from a dye mixture. The materials are recyclable for five cycles without significant loss of their performance. The mechanisms of adsorption and catalysis were also investigated.

  • 5.
    Ahmed, Trifa Mohammad
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Bergvall, Christoffer
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Emissions of particulate associated oxygenated and native polycyclic aromatic hydrocarbons from vehicles powered by ethanol/gasoline fuel blends2018In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 214, p. 381-385Article in journal (Refereed)
    Abstract [en]

    Emission factors for oxygenated polycyclic aromatic hydrocarbons (OPAHs) and PAHs have been determined from two different fuel flexible light duty vehicles operated at -7 degrees C in the New European Driving Cycle (NEDC) and at +22 degrees C in the Artemis Driving Cycle (ADC). Three different gasoline/ethanol blends, commercially available in Sweden, were tested i.e., gasoline E5, with 5% v/v ethanol and ethanol fuel E85 with 85% v/v ethanol and winter time quality E70 with 70% v/v ethanol, respectively. The results showed greatly increased emissions of both OPAHs and PAHs at cold engine start conditions (-7 degrees C in the NEDC) compared to warm engine start (+ 22 degrees C in the ADC). For the OPAHs, higher average total emission factors were obtained when running on E85 compared to E5 at both cold 2.72 mu g/km vs 1.11 mu g/km and warm 0.19 mu g/km vs 0.11 mu g/km starting conditions with the highest emissions when using E70 at -7 degrees C 4.12 mu g/km. The same trend was found for the PAHs at cold engine start with higher average total emission factors when using ethanol fuel 71.5 mu g/km and 60.0 mu g/km for E70 and E85, respectively compared to gasoline E5 (20.2 mu g/km). Slightly higher average total PAH emissions were obtained when operating at + 22 degrees C with E5 compared to with E85 1.23 mu g/km vs 0.72 mu g/km.

  • 6.
    Akhtar, Farid
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sjöberg, Erik
    Korelskiy, Danil
    Rayson, Mark
    Hedlund, Jonas
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Preparation of graded silicalite-1 substrates for all-zeolite membranes with excellent CO2/H-2 separation performance2015In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 493, p. 206-211Article in journal (Refereed)
    Abstract [en]

    Graded silicalite-1 substrates with a high gas permeability and low surface roughness have been produced by pulsed current processing of a thin coating of a submicron silicalite-1 powder onto a powder body of coarser silicalite-1 crystals. Thin zeolite films have been hydrothermally grown onto the graded silicalite-1 support and the all-zeolite membranes display an excellent CO2/H-2 separation factor of 12 at 0 degrees C and a CO2 permeance of 21.3 x 10(-7) mol m(-2) s(-1) Pa-1 for an equimolar CO2/H-2 feed at 505 kPa and 101 kPa helium sweep gas. Thermal cracking estimates based on calculated surface energies and measured thermal expansion coefficients suggest that all-zeolite membranes with a minimal thermal expansion mismatch between the graded substrate and the zeolite film should remain crack-free during thermal cycling and the critical calcination step.

  • 7. Ali, Asad
    et al.
    Laaksonen, Aatto
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden; “Petru Poni” Institute of Macromolecular Chemistry, Romania; Nanjing Tech University, China.
    Huang, Guo
    Hussain, Shahid
    Luo, Shuiping
    Chen, Wen
    Shen, Pei Kang
    Zhu, Jinliang
    Ji, Xiaoyan
    Emerging strategies and developments in oxygen reduction reaction using high-performance platinum-based electrocatalysts2024In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 17, no 5, p. 3516-3532Article, review/survey (Refereed)
    Abstract [en]

    The global practical implementation of proton exchange membrane fuel cells (PEMFCs) heavily relies on the advancement of highly effective platinum (Pt)-based electrocatalysts for the oxygen reduction reaction (ORR). To achieve high ORR performance, electrocatalysts with highly accessible reactive surfaces are needed to promote the uncovering of active positions for easy mass transportation. In this critical review, we introduce different approaches for the emerging development of effective ORR electrocatalysts, which offer high activity and durability. The strategies, including morphological engineering, geometric configuration modification via supporting materials, alloys regulation, core-shell, and confinement engineering of single atom electrocatalysts (SAEs), are discussed in line with the goals and requirements of ORR performance enhancement. We review the ongoing development of Pt electrocatalysts based on the syntheses, nanoarchitecture, electrochemical performances, and stability. We eventually explore the obstacles and research directions on further developing more effective electrocatalysts.

     

  • 8. Argyropoulos, Dimitris D. S.
    et al.
    Crestini, Claudia
    Dahlstrand, Christian
    Furusjö, Erik
    Gioia, Claudio
    Jedvert, Kerstin
    Henriksson, Gunnar
    Hulteberg, Christian
    Lawoko, Martin
    Pierrou, Clara
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Ren Fuel K2B AB, Sweden; RenFuel Materials AB, Sweden; Chulalongkorn University, Thailand.
    Subbotina, Elena
    Wallmo, Henrik
    Wimby, Martin
    Kraft Lignin: A Valuable, Sustainable Resource, Opportunities and Challenges2023In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 16, no 23, article id e202300492Article, review/survey (Refereed)
    Abstract [en]

    Kraft lignin, a by-product from the production of pulp, is currently incinerated in the recovery boiler during the chemical recovery cycle, generating valuable bioenergy and recycling inorganic chemicals to the pulping process operation. Removing lignin from the black liquor or its gasification lowers the recovery boiler load enabling increased pulp production. During the past ten years, lignin separation technologies have emerged and the interest of the research community to valorize this underutilized resource has been invigorated. The aim of this Review is to give (1) a dedicated overview of the kraft process with a focus on the lignin, (2) an overview of applications that are being developed, and (3) a techno-economic and life cycle asseeements of value chains from black liquor to different products. Overall, it is anticipated that this effort will inspire further work for developing and using kraft lignin as a commodity raw material for new applications undeniably promoting pivotal global sustainability concerns.

  • 9.
    Bacsik, Zoltan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cheung, Ocean
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Vasiliev, Petr
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Selective separation of CO2 and CH4 for biogas upgrading on zeolite NaKA and SAPO-562016In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 162, p. 613-621Article in journal (Refereed)
    Abstract [en]

    Several commercial and potential adsorbents were investigated for the separation of CO2 from CH4, which is relevant for the upgrading of raw biogas. The main focus of the paper was on the working capacities and selectivities of the adsorbents for a generic vacuum swing adsorption (VSA) process. Zeolites 4A and 13X had good estimated CO2-over-CH4 selectivities and reasonably high working capacities for the removal of CO2. A variant of zeolite A - vertical bar Na12-Kx vertical bar-LTA (with 1.8 <= x <= 3.2), had at least the same working capacity as zeolite 4A but with a significantly improved selectivity. Hence, the environmentally important CH4 slip can be minimized with this vertical bar Na12-Kx vertical bar-LTA sorbent. If a high working capacity for CO2 removal is the most important characteristic for a VSA process, then silicoaluminum phosphate, specifically SAPO-56, appeared to be the best candidate among the studied sorbents. In addition, SAPO-56 had a substantially high estimated CO2-over-CH4 selectivity with a value between similar to 20 and 30.

  • 10. Bajwa, Anjali
    et al.
    Moraga, Francisca
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Balakrishnan, Malini
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Batra, Vidya S.
    Activated Carbon Monoliths by Pressureless Technique for Environmental Applications2015In: Environmental Progress & Sustainable Energy, ISSN 1944-7442, E-ISSN 1944-7450, Vol. 34, no 5, p. 1420-1426Article in journal (Refereed)
    Abstract [en]

    Carbon monoliths have been prepared through simple procedure by carbonization in inert atmosphere at 550 C from commercial activated carbon and from unburned carbon in it ykste bctgasse fly asb; US nig, In 0 different kin dS phenolic resin binders. The bagasse fly ash was collected ft on; sugar mills where bagasse is used as a biomass based fuel for cogeneration. Commercial actuated carbon based monoliths whet -e 5 and 10 wt % of the actuated carbon had been replaced by iron oxide (hematite) were dic0 prepared. Results indicate that BET sutfac:e area decreases upon carbonization and loading of hematite. Scanning electron microscopy studies shows that the iron oxide is well distributed over the monoliths and X-ray diffraction shows that it is reduced to magnetite during carbonization. Temperature programmed reduction eAperintents show that the iron oxides on the monoliths are redox active. The monoliths based on commercial activated carbon show 80% remotwl of phenol in dihtted phenol based water solutions whereas unburned carbon derived monoliths showed 5-/ % removal in similar solution.

  • 11. Bartling, Andrew W.
    et al.
    Stone, Michael L.
    Hanes, Rebecca J.
    Bhatt, Arpit
    Zhang, Yimin
    Biddy, Mary J.
    Davis, Ryan
    Kruger, Jacob S.
    Thornburg, Nicholas E.
    Luterbacher, Jeremy S.
    Rinaldi, Roberto
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sels, Bert F.
    Román-Leshkov, Yuriy
    Beckham, Gregg T.
    Techno-economic analysis and life cycle assessment of a biorefinery utilizing reductive catalytic fractionation2021In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 14, no 8, p. 4147-4168Article in journal (Refereed)
    Abstract [en]

    Reductive catalytic fractionation (RCF) is a promising approach to fractionate lignocellulose and convert lignin to a narrow product slate. To guide research towards commercialization, cost and sustainability must be considered. Here we report a techno-economic analysis (TEA), life cycle assessment (LCA), and air emission analysis of the RCF process, wherein biomass carbohydrates are converted to ethanol and the RCF oil is the lignin-derived product. The base-case process, using a feedstock supply of 2000 dry metric tons per day, methanol as a solvent, and H-2 gas as a hydrogen source, predicts a minimum selling price (MSP) of crude RCF oil of $1.13 per kg when ethanol is sold at $2.50 per gallon of gasoline-equivalent ($0.66 per liter of gasoline-equivalent). We estimate that the RCF process accounts for 57% of biorefinery installed capital costs, 77% of positive life cycle global warming potential (GWP) (excluding carbon uptake), and 43% of positive cumulative energy demand (CED). Of $563.7 MM total installed capital costs, the RCF area accounts for $323.5 MM, driven by high-pressure reactors. Solvent recycle and water removal via distillation incur a process heat demand equivalent to 73% of the biomass energy content, and accounts for 35% of total operating costs. In contrast, H-2 cost and catalyst recycle are relatively minor contributors to operating costs and environmental impacts. In the carbohydrate-rich pulps, polysaccharide retention is predicted not to substantially affect the RCF oil MSP. Analysis of cases using different solvents and hemicellulose as an in situ hydrogen donor reveals that reducing reactor pressure and the use of low vapor pressure solvents could reduce both capital costs and environmental impacts. Processes that reduce the energy demand for solvent separation also improve GWP, CED, and air emissions. Additionally, despite requiring natural gas imports, converting lignin as a biorefinery co-product could significantly reduce non-greenhouse gas air emissions compared to burning lignin. Overall, this study suggests that research should prioritize ways to lower RCF operating pressure to reduce capital expenses associated with high-pressure reactors, minimize solvent loading to reduce reactor size and energy required for solvent recovery, implement condensed-phase separations for solvent recovery, and utilize the entirety of RCF oil to maximize value-added product revenues.

  • 12. Bello, Estefania
    et al.
    Ferri, Pau
    Nero, Mathias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Willhammar, Tom
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Millet, Isabel
    Schütze, Frank W.
    van Tendeloo, Leen
    Vennestrøm, Peter N. R.
    Boronat, Mercedes
    Corma, Avelino
    Moliner, Manuel
    NH3-SCR catalysts for heavy-duty diesel vehicles: Preparation of CHA-type zeolites with low-cost templates2022In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 303, article id 120928Article in journal (Refereed)
    Abstract [en]

    Computer-assistance allows selecting the most adequate low-cost organic structure directing agents (OSDAs) for the crystallization of Al-rich CHA-type zeolites. The host-guest stabilization energies of tetraethylammonium (TEA), methyltriethylammonium (MTEA) and dimethyldiethylammonium (DMDEA), in combination with Na, were first theoretically evaluated. This ab-initio analysis reveals that two TEA show a serious steric hindrance in a cha cavity, whereas two MTEA would present excellent host-guest confinements. The synthesis of Al-rich CHA-type zeolites has been accomplished using TEA and MTEA. Electron diffraction and high-resolution transmission electron microscopy reveal large CHA-domains with narrow faulted GME-domains in the CHAtype material synthesized with TEA, confirming the better OSDA-directing roles of MTEA cations towards the cha cavity, in good agreement with DFT calculations. Cu-exchanged Al-rich CHA-type samples achieved with MTEA and TEA show excellent catalytic activity and hydrothermal stability for the selective catalytic reduction (SCR) of NOx with ammonia under conditions relevant for future heavy duty diesel conditions.

  • 13. Benavente, Veronica
    et al.
    Lage, Sandra
    Stockholm University, Faculty of Science, Department of Environmental Science. Swedish University of Agricultural Sciences, Sweden.
    Gentili, Francesco G.
    Jansson, Stina
    Influence of lipid extraction and processing conditions on hydrothermal conversion of microalgae feedstocks - Effect on hydrochar composition, secondary char formation and phytotoxicity2022In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 428, article id 129559Article in journal (Refereed)
    Abstract [en]

    This study investigated the effect of lipid extraction of microalgae feedstocks subjected to hydrothermal carbonization (HTC) with regard to the carbonization degree, chemical composition and phytotoxicity of hydrochars produced under different reaction temperatures and residence times. Special attention was given to the formation and composition of secondary char, as this part of the hydrochar may be of particular importance for environmental and technical applications. A microalgae polyculture grown in municipal wastewater was extracted to retrieve lipids, and both unextracted (MA) and extracted microalgae (EMA) were used to produce hydrochars at 180-240 degrees C for 1-4 h. The composition of the hydrochars was thoroughly characterized by elemental analysis, thermogravimetric analysis and pyrolysis-gas chromatography/mass spectrometry analysis. MA exhibited a greater carbonization degree than EMA and contained higher amounts of secondary char under the same processing conditions. During the carbonization of EMA, more decomposition products remained in the liquid phase and less polymerization occurred than for MA, which explained the lower solid yield of EMA-derived hydrochars in comparison to MA hydrochars. Consequently, although they contained potentially toxic substances (i.e., carboxylic acids, aldehydes and ketones), the EMA-derived hydrochars exhibited a lower phytotoxic potential. This indicates that low-temperature hydrochars containing less than 10% of extractives might be suitable as soil amendments, whereas extractive-rich hydrochars would be more appropriate for other long-term applications, such as adsorbents for contaminant removal, energy storage and composite materials. Detailed characterization of microalgae-derived hydrochars is required to enable the most suitable application areas to be identified for these materials, and thereby make full use of their function as carbon sinks.

  • 14. Bletsa, Eleni
    et al.
    Merkl, Padryk
    Thersleff, Thomas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Normark, Staffan
    Henriques-Normark, Birgitta
    Sotiriou, Georgios A.
    Highly durable photocatalytic titanium suboxide–polymer nanocomposite films with visible light-triggered antibiofilm activity2023In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 454, part 1, article id 139971Article in journal (Refereed)
    Abstract [en]

    Bacterial biofilms on medical devices may result in infections with significant societal burden. One drug-free strategy against biofilms is photocatalysis, in which a semiconducting coating is applied on the medical device and irradiated with light to generate reactive oxygen species providing an on-demand disinfection approach. However, most photocatalytic materials are active in the harmful UV range rendering them unsuitable for biomedical applications. Furthermore, the main manufacturing bottleneck today for antibiofilm coatings is their poor durability. To address these challenges, here we produced silver/titanium-suboxide nanoparticles that are photocatalytically active in the visible-light range. Moreover, we directly deposited the nanoparticles as porous coatings on substrates in situ during their aerosol synthesis. To enhance their durability, we infused the fabricated porous coatings with a polymer solution barely covering the photocatalytic particle film, resulting in the formation of polymer nanocomposite coatings. The optimized polymer nanocomposite films exhibit several cycles of triggered, on-demand biofilm eradication activity under short visible light illumination of 15–90 min with no significant intrinsic cytotoxicity to mammalian cells. The developed films can be considered as a suitable coating material for medical devices, such as catheters, ventilators, wound meshes, and others, that may require repeated disinfection during use.

  • 15. Chai, Jiali
    et al.
    Han, Ning
    Feng, Shihui
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Huang, Xiaoxiong
    Tang, Bohejin
    Zhang, Wei
    Insights on Titanium-based chalcogenides TiX2 (X = O, S, Se) as LIBs/SIBs anode materials2023In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 453, article id 139768Article, review/survey (Refereed)
    Abstract [en]

    Ti-based chalcogenides TiX2 (X = O, S, Se) are widely used in the research of battery electrode materials due to its excellent rate performance and good chemical stability. In this paper, in order to improve the electrochemical performance of lithium-ion batteries (LIBs) and sodium ion batteries (SIBs), and further improve the application prospect of batteries, the strategies for design and preparation of LIBs/SIBs anode materials for Ti-based chalcogenides TiX2 (X = O, S, Se) are reviewed. The effects of the internal morphology modification, surface structure vacancy and composite with other material of TiX2 (X = O, S, Se) as LIBs/SIBs anode materials are analyzed in detail. On this basis, the application prospect of TiX2 (X = O, S, Se) as LIBs/SIBs anode is prospected, it is expected to fill the research of diversified applications of LIBs/SIBs anode materials.

  • 16.
    Chang, Jian
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). King Abdullah University of Science and Technology, Saudi Arabia.
    Ong, Chisiang
    Shi, Yusuf
    Yuan, Jiayin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ahmed, Zeyad
    Wang, Peng
    Smart Sand by Surface Engineering: Toward Controllable Oil/Water Separation2021In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 60, no 26, p. 9475-9481Article in journal (Refereed)
    Abstract [en]

    Sand, an abundant resource from the nature, is a promising candidate for oil/water separation. Herein, raw sand was designed with switchable surface wettability to enable recyclability and versatility in practical oil/water separation. The smart sand was fabricated by grafting pH-responsive poly(4-vinylpyridine) (P4VP) and oleophilic/hydrophobic octadecyltrimethoxysilane (OTS) onto its surface. The decorated sand can be used as the oil sorbent for controllable oil sorption and desorption in response to different pHs, as well as a filter to selectively separate either oil or water on demand. This novel design offers an intelligent, low-cost, large-scale, and highly efficient route to potentially settle the issues of industrial oily wastewater and oil spill.

  • 17.
    Chang, Jian
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Miao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhao, Qiang
    Qu, Liangti
    Yuan, Jiayin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ultratough and ultrastrong graphene oxide hybrid films via a polycationitrile approach2021In: Nanoscale Horizons, ISSN 2055-6764, E-ISSN 2055-6756, Vol. 6, no 4, p. 341-347Article in journal (Refereed)
    Abstract [en]

    Graphene oxide (GO) is a classic two dimensional (2D) building block that can be used to develop high-performance materials for numerous applications, particularly in the energy and environmental fields. Currently, the precise assembly of GO nanosheets into macroscopic nanohybrids of superior strength and toughness is desirable, and faces challenges and trade-offs. Herein, we exploited the freshly established polycationitrile method as a powerful molecular crosslinking strategy to engineer ultratough and ultrastrong GO/polymer hybrid films, in which a covalent triazine-based network was constructed in a mild condition to reinforce the interface between GO nanosheets. The tensile strength and toughness reached 585 +/- 25 MPa and 14.93 +/- 1.09 MJ m(-3), respectively, which, to the best of our knowledge, are the current world records in all GO-based hybrid films. As an added merit of the tailor-made polymer crosslinker, the high mechanical performance can be maintained in large part at an extremely high relative humidity of 98%. This emerging interface-engineering approach paves a new avenue to produce integrated strong-and-tough 2D nanohybrid materials that are useful in aerospace, artificial muscle, energy harvesting, tissue engineering and more.

  • 18.
    Church, Tamara L.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kriechbaum, Konstantin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Emami, S. Noushin
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Greenwich, U.K..
    Mozuraitis, Raimondas
    Stockholm University, Faculty of Science, Department of Zoology.
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Functional Wood-Foam Composites for Controlled Uptake and Release2021In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 9, no 46, p. 15571-15581Article in journal (Refereed)
    Abstract [en]

    Wood-foam hierarchical composites were produced via the shear-forced infiltration of shear-thinning nanocellulose-based foams or gels into the tracheids of Picea abies. Shear processing viscoelastic and shear-thinning aqueous foams composed of cellulose nanocrystals, methylcellulose, and tannic acid (total solids content: 2 wt %) resulted in foam-filled wood composites containing 15-20 wt % foam, with open foam structures and compression strengths similar to those of unmodified P. abies. An amino-functionalized nanocellulose-containing foam confined in wood reversibly adsorbed CO2, retaining 15% of its theoretical uptake capacity over 50 cycles in the thermogravimetric analyzer, and a citronellol-loaded foam released this mosquito-repellent compound over four days, as evaluated using solid-phase microextraction. Shear-forced infiltration of functional foams into wood is an operationally simple route to hierarchically porous composites based on renewable materials.

  • 19. Cladek, Bernadette R.
    et al.
    Ramirez-Cuesta, A. J.
    Everett, S. Michelle
    McDonnell, Marshall T.
    Daemen, Luke
    Cheng, Yongqiang
    B. Brant Carvalho, Paulo H.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tulk, Christopher
    Tucker, Matthew G.
    Keffer, David J.
    Rawn, Claudia J.
    In situ inelastic neutron scattering of mixed CH4–CO2 hydrates2022In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 327, article id 125197Article in journal (Refereed)
    Abstract [en]

    An abundant source of CH4 can be found in natural hydrate deposits. Recent demonstration of CH4 recovery from hydrates via CO2 exchange has revealed the potential as a fuel source that also provides a medium for carbon sequestration. It is vital to understand the structural and dynamic impacts of guest variation in CH4, CO2, and mixed hydrates and link the results to the stability of various deposits in nature, harvesting methane, and sequestering CO2. Molecular vibrations are examined in CH4, CO2, and mixed CH4-CO2 hydrates at 5 and 190 K and Xe hydrates for comparison. Inelastic neutron scattering (INS) is an ideal spectroscopy technique to observe the dynamic modes in the hydrate structure and enclathrated CH4, as it is extremely sensitive to 1H. The presence of CO2 in hydrates tightens the lattice. It introduces more active librational modes to the host lattice, while hindering the motion of CH4 in mixed CH4-CO2 hydrate at 5 K. At 190 K, a large broadening of the CH4 librational modes indicates disorder in the structure leading to dissociation.

  • 20.
    de Bruin-Dickason, Caspar
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Budnyk, Serhiy
    Piątek, Jędrzej
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Jenei, István-Zoltán
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Budnyak, Tetyana M.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Slabon, Adam
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Valorisation of used lithium-ion batteries into nanostructured catalysts for green hydrogen from boranes2020In: Materials Advances, E-ISSN 2633-5409, Vol. 1, no 7, p. 2279-2285Article in journal (Refereed)
    Abstract [en]

    Cobalt-based Li-ion batteries are produced globally on a massive scale, but most are discarded to landfill at the end of their useful lifetime. In this work, an efficient cobalt catalyst for the hydrolysis of sodium borohydride to dihydrogen was prepared from lithium ion battery waste, providing a second life for valuable minerals. This material is composed of a mixed metal cobalt-aluminium oxide supported on graphene, as elucidated by a combined FTIR, Raman, SEM, scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) and energy-dispersive X-ray spectroscopy (EDS) study. The obtained metal oxide material, which exhibits an average oxidation state for Co of 2.45, is a languid catalyst at room temperature, but rapid hydrogen production of up to 49 L(H-2) min(-1) g(-1)(Co) was observed in catalytic runs heated to 70 degrees C. This carbon-supported cobalt catalyst is competitive with designed cobalt nanostructured catalysts prepared from pure precursors. This work is illustrative of the opportunities which arise when e-waste is utilised as a mineral resource within the scope of a circular economy.

  • 21.
    Degerman, David
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Shipilin, Mikhail
    Stockholm University, Faculty of Science, Department of Physics.
    Lömker, Patrick
    Stockholm University, Faculty of Science, Department of Physics.
    Soldemo, Markus
    Stockholm University, Faculty of Science, Department of Physics.
    Goodwin, Christopher M.
    Stockholm University, Faculty of Science, Department of Physics.
    Wagstaffe, Michael
    Börner, Mia
    Stockholm University, Faculty of Science, Department of Physics.
    Schlueter, Christoph
    Amann, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Effect of CO2-Rich Syngas on the Chemical State of Fe(110) during Fischer-Tropsch Synthesis2024In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 128, no 13, p. 5542-5552Article in journal (Refereed)
    Abstract [en]

    We have used in situ X-ray photoelectron spectroscopy to obtain information about the chemical state of a Fe single-crystal catalyst upon addition of CO2 in the syngas feed during Fischer–Tropsch synthesis (FTS) between 85 and 550 mbar. We found that at certain temperatures, the ternary mixture of CO, CO2, and H2 yields a chemical state which is resemblant of neither the CO hydrogenation nor the CO2 hydrogenation reaction mixtures in isolation. The addition of CO2 to a CO + H2 reaction mixture mostly affects the chemical state at low-temperature FTS conditions (i.e., below 254 °C). In this temperature span, the ternary reaction mixture resulted in a carburized surface, whereas the CO + H2 reaction led to surface oxidation. We propose a hypothesis, where a carbonate intermediate produced by CO2 interaction with Fe oxide aids the reduction of the Fe oxide, paving the way for the carburization of the Fe by dissociated CO. Very small differences in the spectra of the CO + H2 and the CO + CO2 + H2 reaction mixtures were observed above 254 °C, suggesting that the CO2 is a spectator in these conditions. Changing the total pressure of both the CO hydrogenation and ternary reaction mixture causes quantitative changes in the spectra at both low- and high-temperature FTS conditions, the degree of oxidation/carburization was affected in the low-temperature-FTS regime, and the degree of hydrocarbon build-up was affected in the high-temperature-FTS.

  • 22. Deiana, Luca
    et al.
    Rafi, Abdolrahim A.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Cordova, Armando
    Artificial Arthropod Exoskeletons/Fungi Cell Walls Integrating Metal and Biocatalysts for Heterogeneous Synergistic Catalysis of Asymmetric Cascade Transformations2023In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 15, no 15, article id e202300250Article in journal (Refereed)
    Abstract [en]

    A novel and sustainable tandem-catalysis system for asymmetric synthesis is disclosed, which is fabricated by bio-inspired self-assembly of artificial arthropod exoskeletons (AAEs) or artificial fungi cell walls (AFCWs) containing two different types of catalysts (enzyme and metal nanoparticles). The heterogeneous integrated enzyme/metal nanoparticle AAE/AFCW systems, which contain chitosan as the main structural component, co-catalyze dynamic kinetic resolution of primary amines via a tandem racemization/enantioselective amidation reaction process to give the corresponding amides in high yields and excellent ee. The heterogeneous AAE/AFCW systems display successful heterogeneous synergistic catalysis at the surfaces since they can catalyze multiple reaction cycles without metal leaching. The use of natural-based and biocompatible structural components makes the AAE/AFCW systems fully biodegradable and renewable, thus fulfilling important green chemistry requirements. 

  • 23. Deng, Ximing
    et al.
    Imhanria, Sarah
    Sun, Yan
    Zhang, Miao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cheng, Yangshuai
    Wang, Wei
    Mo, Fe bimetallic carbide composite as high stability electrocatalyst for oxygen reduction reaction2022In: Journal of Environmental Chemical Engineering, ISSN 2213-2929, Vol. 10, no 3, article id 108052Article in journal (Refereed)
    Abstract [en]

    Developing inexpensive but efficient electrocatalysts for oxygen reduction reactions (ORR) is critical to the design of zinc-air battery (ZAB). Here, we report a good ORR electrocatalyst (MoFeCx-NC) composed of nitrogen-doped carbon armored by ferro-molybdenum binary carbides. The physical characterization of MoFeCx-NC by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) show that MoFeCx-NC is composed of amorphous bimetallic carbides and N-doped carbon. In addition, the electrochemical test shows that its more positive onset potential of 0.962 V and better half-wave potential of 0.847 V, almost close to Pt/C (Eonset = 0.957 V, E1/2 = 0.854 V). Furthermore, the MoFeCx-NC assembled ZAB exhibits a good peak power density of 79.14 mW cm−2 and an impressive 1.40 V discharge voltage, indicating that the obtained MoFeCx-NC is an ideal for the future ORR electrocatalyst.

  • 24.
    Di Francesco, Davide
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rigo, Davide
    Baddigam, Kiran Reddy
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Selva, Maurizio
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Chulalongkorn University, Thailand.
    A New Family of Renewable Thermosets: Kraft Lignin Poly-adipates2022In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 15, no 11, article id e202200326Article in journal (Refereed)
    Abstract [en]

    Thermosetting polymeric materials have advantageous properties and are therefore used in numerous applications. In this study, it was hypothesized and ultimately shown that thermosets could be derived from comparably sustainable sub-components. A two-step procedure to produce a thermoset comprising of Kraft lignin (KL) and the cross-linker adipic acid (AdA) was developed. The cross-linking was activated by means of an acetylating agent comprising isopropenyl acetate (IPA) to form a cross-linking mixture (CLM). The cross-linking was confirmed by FTIR and solid-state NMR spectroscopy, and the esterification reactions were further studied using model compounds. When the KL lignin was mixed with the CLM, partial esterification occurred to yield a homogeneous viscous liquid that could easily be poured into a mold, as the first step in the procedure. Without any additions, the mold was heated and the material transformed into a thermoset by reaction of the two carboxylic acid-derivatives of AdA and KL in the second step.

  • 25. Dogaris, Ioannis
    et al.
    Pylypchuk, Ievgen V.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). KTH Royal Institute of Technology, Sweden.
    Henriksson, Gunnar
    Abbadessa, Anna
    Polyelectrolyte complexes based on a novel and sustainable hemicellulose-rich lignosulphonate for drug delivery applications2024In: Drug Delivery and Translational Research, ISSN 2190-393X, E-ISSN 2190-3948 Article in journal (Refereed)
    Abstract [en]

    Polyelectrolyte complexes (PECs) are polymeric structures formed by the self-assembly of oppositely charged polymers. Novel biomaterials based on PECs are currently under investigation as drug delivery systems, among other applications. This strategy leverages the ability of PECs to entrap drugs under mild conditions and control their release. In this study, we combined a novel and sustainably produced hemicellulose-rich lignosulphonate polymer (EH, negatively charged) with polyethyleneimine (PEI) or chitosan (CH, positively charged) and agar for the development of drug-releasing PECs. A preliminary screening demonstrated the effect of several parameters (polyelectrolyte ratio, temperature, and type of polycation) on PECs formation. From this, selected formulations were further characterized in terms of thermal properties, surface morphology at the microscale, stability, and ability to load and release methylene blue (MB) as a model drug. EH/PEI complexes had a more pronounced gel-like behaviour compared to the EH/CH complexes. Differential scanning calorimetry (DSC) results supported the establishment of polymeric interactions during complexation. Overall, PECs' stability was positively affected by low pH, ratios close to 1:1, and the addition of agar. PECs with higher EH content showed a higher MB loading, likely promoted by stronger electrostatic interactions. The EH/CH formulation enriched with agar showed the best sustained release profile of MB during the first 30 h in a pH-dependent environment simulating the gastrointestinal tract. Overall, we defined the conditions to formulate novel PECs based on a sustainable hemicellulose-rich lignosulphonate for potential applications in drug delivery, which promotes the valuable synergy between sustainability and the biomedical field.

  • 26.
    Elihn, Karine
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Berg, Peter
    Lidén, Göran
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Correlation between airborne particle concentrations in seven industrial plants and estimated respiratory tract deposition by number, mass and elemental composition2011In: Journal of Aerosol Science, ISSN 0021-8502, E-ISSN 1879-1964, Vol. 42, no 2, p. 127-141Article in journal (Refereed)
    Abstract [en]

    The number and mass distribution of airborne particles were recorded in several industrial plants. From the data obtained, particle deposition was estimated in three regions of the respiratory tract using the ICRP grand average deposition model based on Hinds' (1999) parameterization. The median diameter was 30-70 nm (number distributions), and >4 mu m (mass distributions) near most work activities, resulting in linear relationships between the deposited number/mass concentrations and the number/mass concentrations in the air. Welding and laser cutting produced particles in the 200-500-nm range; total deposition was small, not in accordance with the linear relationship observed for the other work activities. The elemental content varied between particle sizes in some workplaces, causing different elements to deposit in different respiratory regions. Iron was the most abundant element in the particles in many of the workplaces; in an iron foundry, however, Fe was most abundant only in the micron-sized particles whereas the nanoparticles mainly comprised Pb and Sb.

  • 27. Emam, Hossam E.
    et al.
    Abdelhamid, Hani Nasser
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Assuit University, Egypt.
    Abdelhameed, Reda M.
    Self-cleaned photoluminescent viscose fabric incorporated lanthanide-organic framework (Ln-MOF)2018In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 159, p. 491-498Article in journal (Refereed)
    Abstract [en]

    Photoluminescent textiles emitted light in ultraviolet (UV)-radiation region has advanced a variety of applications including military and police clothes. The current study reports the preparation of photoluminescent viscose fabrics incorporated lanthanide metal-organic framework (Ln-MOF) and their applications for self-cleaning. In situ growth of Ln (Eu3+, Tb3+) MOF into viscose fabrics were achieved using Ln (NO3)(3) and 1,2,4,5-benzenetetracarboxylic dianhydride as organic ligand. The in-growth Ln-MOF within fabrics were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, energy dispersive X-ray, and fluorescence spectroscopy. Under the UV lamb (345 nm), Eu-MOF@viscose fabric and Tb-MOF@viscose fabric visually emitted red and green color, respectively. The excitation-emission spectra showed the spectra for the D-5(0)-> F-7(0.4) transitions and D-5(4)-> F-7(5) transitions in case of Eu-MOF and Tb-MOF@viscose fabrics, respectively. The photoluminescent properties of Ln-MOF@viscose fabrics were enhanced after reactive dying process. The self-cleaning functions of Ln-MOF@viscose fabrics were estimated through studying the photo-degradation of Rhodamine B (RhB) dye over the fabrics. After 120 min irradiation time, the photo-degradation of RhB dye was 85-97%, indicating high performance of Ln-MOF@viscose fabric. The materials are promising for advanced applications including protective clothing, textile-based sensors, smart tagging and tickets.

  • 28. Esakkimuthu, Esakkiammal Sudha
    et al.
    DeVallance, David
    Pylypchuk, Ievgen V.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Moreno, Adrian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sipponen, Mika H.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Multifunctional lignin-poly (lactic acid) biocomposites for packaging applications2022In: Frontiers in Bioengineering and Biotechnology, E-ISSN 2296-4185, Vol. 10, article id 1025076Article in journal (Refereed)
    Abstract [en]

    Lignin is the most abundant aromatic biopolymer with many promising features but also shortcomings as a filler in polymer blends. The main objective of this work was to improve the processability and compatibility of lignin with poly (lactic acid) (PLA) through etherification of lignin. Commercial kraft lignin (KL) and oxypropylated kraft lignin (OPKL) were blended with PLA at different weight percentages (1, 5, 10, 20, and 40%) followed by injection molding. Low lignin contents between 1 and 10% generally had a favorable impact on mechanical strength and moduli as well as functional properties of the PLA-based composites. Unmodified lignin with free phenolic hydroxyl groups rendered the composites with antioxidant activity, as measured by radical scavenging and lipid peroxidation tests. Incorporating 5–10% of KL or OPKL improved the thermal stability of the composites within the 300–350°C region. DSC analysis showed that the glass transition temperature values were systematically decreased upon addition of KL and OPKL into PLA polymer. However, low lignin contents of 1 and 5% decreased the cold crystallization temperature of PLA. The composites of KL and OPKL with PLA exhibited good stabilities in the migration test, with values of 17 mg kg−1 and 23 mg kg−1 even at higher lignin content 40%, i.e., well below the limit defined in a European standard (60 mg kg−1). These results suggest oxypropylated lignin as a functional filler in PLA for safe and functional food packaging and antioxidant applications.

  • 29.
    Esakkimuthu, Esakkiammal Sudha
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). InnoRenew CoE, Slovenia.
    Ponnuchamy, Veerapandian
    Sipponen, Mika H.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    DeVallance, David
    Elucidating intermolecular forces to improve compatibility of kraft lignin in poly(lactic acid)2024In: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 12, article id 1347147Article in journal (Refereed)
    Abstract [en]

    Owing to its abundant supply from renewable resources, lignin has emerged as a promising functional filler for the development of sustainable composite materials. However, achieving good interfacial compatibility between lignin and synthetic polymers, particularly poly (lactic acid) (PLA), remains a fundamental challenge. To advance the development of high-performance bio-based composites incorporating lignin and PLA, our study has scrutinized to unravel the nuances of interfacial binding interactions with the lignin and PLA composite system. Molecular level and experimental examinations were employed to decipher fundamental mechanisms governing and demonstrating the interfacial adhesion. We synthesized casted films of lignin/PLA and acetylated lignin/PLA at varying weight percentages of lignin (5%, 10%, and 20%) and comprehensively investigated their physicochemical and mechanical properties. The inclusion of acetylated lignin in the composites resulted in improved mechanical strength and Young’s modulus, while the glass transition temperature and melting point were reduced compared to neat PLA. Systematic variations in these properties revealed distinct compatibility behaviors between unmodified lignin and acetylated lignin when incorporated into PLA. Molecular dynamics (MD) simulation results elucidated that the observed changes in material properties were primarily attributed to the acetylation of lignin. Acetylated lignin exhibited lower Coulombic interaction energy and higher van der Waals forces, indicating a stronger affinity to PLA and a reduced propensity for intermolecular aggregation compared to unmodified lignin. Our findings highlight the critical role of controlling intermolecular interactions and lignin aggregation to develop PLA composites with predictable performance for new applications, such as functional packaging materials.

  • 30. Farag, Mohamed A.
    et al.
    Jomaa, Suzan A.
    Abd El-Wahed, Aida
    El-Seedi, Hesham R.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Uppsala University, Sweden; Al-Rayan Colleges, Saudi Arabia; Jiangsu University, China.
    The Many Faces of Kefir Fermented Dairy Products: Quality Characteristics, Flavour Chemistry, Nutritional Value, Health Benefits, and Safety2020In: Nutrients, E-ISSN 2072-6643, Vol. 12, no 2, article id 346Article, review/survey (Refereed)
    Abstract [en]

    Kefir is a dairy product that can be prepared from different milk types, such as goat, buffalo, sheep, camel, or cow via microbial fermentation (inoculating milk with kefir grains). As such, kefir contains various bacteria and yeasts which influence its chemical and sensory characteristics. A mixture of two kinds of milk promotes kefir sensory and rheological properties aside from improving its nutritional value. Additives such as inulin can also enrich kefir's health qualities and organoleptic characters. Several metabolic products are generated during kefir production and account for its distinct flavour and aroma: Lactic acid, ethanol, carbon dioxide, and aroma compounds such as acetoin and acetaldehyde. During the storage process, microbiological, physicochemical, and sensory characteristics of kefir can further undergo changes, some of which improve its shelf life. Kefir exhibits many health benefits owing to its antimicrobial, anticancer, gastrointestinal tract effects, gut microbiota modulation and anti-diabetic effects. The current review presents the state of the art relating to the role of probiotics, prebiotics, additives, and different manufacturing practices in the context of kefir's physicochemical, sensory, and chemical properties. A review of kefir's many nutritional and health benefits, underlying chemistry and limitations for usage is presented.

  • 31.
    Fijoł, Natalia
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Wallenberg Wood Science Center, Sweden.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Wallenberg Wood Science Center, Sweden.
    Accelerated ageing of 3D printed water purification filters based on PLA reinforced with green nanofibers2023In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 129, article id 108270Article in journal (Refereed)
    Abstract [en]

    This study investigates the ageing behavior of polylactic acid (PLA) and PLA-based biocomposites reinforced with either 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO) - oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) in water. Fused deposition modeling (FDM) was used to create water filters, which underwent aging tests at various temperatures over 19 weeks. Thermomechanical results show that while the addition of TCNF and ChNF improves the mechanical performance of PLA-based filters in dry conditions, it has the opposite effect after exposure to water. The impact of prolonged water exposure on Young's modulus and toughness was more significant in biocomposites than in unmodified PLA filters. The TCNF/PLA and ChNF/PLA filters saw a substantial ∼10 °C drop in glass transition temperature (Tg) after 3 weeks, while pure PLA remained nearly unaffected for up to 7 weeks. The mechanical tests allowed to estimate the service life of the 3D printed filters using the Arrhenius model. It was shown that the TCNF/PLA and ChNF/PLA filters can be utilized at room temperature water for up to 8 and 5 months, respectively, until they lose 50 % of their initial ability to resist deformation. In the same conditions, PLA filters can serve for up to 3.5 years. In conclusion, this study highlights the importance of considering the degradation behaviour of biocomposites when developing sustainable materials for water treatment applications.

  • 32. Gao, Qingwei
    et al.
    Zhang, Yumeng
    Laaksonen, Aatto
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Nanjing Tech University, China; Luleå University of Technology, Sweden; Petru Poni Institute of Macromolecular Chemistry, Romania.
    Zhu, Yudan
    Ji, Xiaoyan
    Zhao, Shuangliang
    Chen, Yaojia
    Lu, Xiaohua
    Effect of dimethyl carbonate on the behavior of water confined in carbon nanotube2021In: Chinese Journal of Chemical Engineering, ISSN 1004-9541, E-ISSN 2210-321X, Vol. 31, p. 177-185Article in journal (Refereed)
    Abstract [en]

    The dehydration of water by dimethyl carbonate (DMC) is of great significance for its application in electrochemistry and oil industry. With the rapid development of nanomaterial, one-dimensional (e.g. carbon nanotube (CNT)) and two-dimensional (e.g. lamellar graphene) materials have been widely used for molecular sieving. In this work, the molecular behavior of dimethyl carbonate/water mixture confined in CNT with varying diameters was studied based on molecular dynamics simulation. Due to different van der Waals interactions for the components in the mixtures with the solid surface, DMC molecules are preferentially adsorbed on the inner surface of the pore wall and formed an adsorption layer. Comparing with the pure water molecules confined in CNT, the adsorption DMC layer shows notable effect on the local compositions and microstructures of water molecules under nanoconfinement, which may result in different water mobility. Our analysis shows that the surface-induced DMC molecules can destroy the hydrogen bonding network of water molecules and result in an uniform and dispersed distribution of water molecules in the tube. These clear molecular understandings can be useful in material design for membrane separation.

  • 33. Goetz, Lee A.
    et al.
    Jalvo, Blanca
    Rosal, Roberto
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Superhydrophilic anti-fouling electrospun cellulose acetate membranes coated with chitin nanocrystals for water filtration2016In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 510, p. 238-248Article in journal (Refereed)
    Abstract [en]

    Electrospun cellulose acetate (CA) random mats were prepared and surface coated with chitin nano crystals (ChNC) to obtain water filtration membranes with tailored surface characteristics. Chitin nano crystals self-assembled on the surface of CA fibers into homogenous nanostructured networks during drying that stabilized via hydrogen bonding and formed webbed film-structures at the junctions of the electrospun fibers. Coating of CA random mats using 5% chitin nanocrystals increased the strength by 131% and stiffness by 340% accompanied by a decrease in strain. The flux through these membranes was as high as 14217 L m(-2) h(-1) at 0.5 bar. The chitin nanocrystal surface coating significantly impacted the surface properties of the membranes, producing a superhydrophilic membrane (contact angle 0) from the original hydrophobic CA mats (contact angle 132 degrees). The coated membranes also showed significant reduction in biofouling and biofilm formation as well as demonstrated improved resistance to fouling with bovine serum albumin and humic acid fouling solutions. The current approach opens up an easy, environmental friendly and efficient route to produce highly hydrophilic membranes with high water flux and low fouling for microfiltration water purification process wash water from food industry for biological contaminants.

  • 34. Gonska, Nathalie
    et al.
    Lopez, Patricia A.
    Lozano-Picazo, Paloma
    Thorpe, Michael
    Guinea, Gustavo
    Johansson, Jan
    Barth, Andreas
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Perez-Rigueiro, Jose
    Rising, Anna
    Structure-Function Relationship of Artificial Spider Silk Fibers Produced by Straining Flow Spinning2020In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 21, no 6, p. 2116-2124Article in journal (Refereed)
    Abstract [en]

    The production of large quantities of artificial spider silk fibers that match the mechanical properties of the native material has turned out to be challenging. Recent advancements in the field make biomimetic spinning approaches an attractive way forward since they allow the spider silk proteins to assemble into the secondary, tertiary, and quaternary structures that are characteristic of the native silk fiber. Straining flow spinning (SFS) is a newly developed and versatile method that allows production under a wide range of processing conditions. Here, we use a recombinant spider silk protein that shows unprecedented water solubility and that is capable of native-like assembly, and we spin it into fibers by the SFS technique. We show that fibers may be spun using different hydrodynamical and chemical conditions and conclude that these spinning conditions affect fiber mechanics. In particular, it was found that the addition of acetonitrile and polyethylene glycol to the collection bath results in fibers with increased beta-sheet content and improved mechanical properties.

  • 35. Granlund, Moa Z.
    et al.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Marita
    Dawody, Jazaer
    Pettersson, Lars J.
    Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel: Aging and characterization2015In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 172, p. 145-153Article in journal (Refereed)
    Abstract [en]

    In this study, three bimetallic catalysts are evaluated for autothermal reforming (AIR) of fuels (1 wt.% Rh and 6 wt.% X (X= Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H-2-TPR, BET surface area analysis, TEM, SEM, and STEM. The material's tendency to coke is investigated by TPO analysis. The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with AIR of complex fuels.

  • 36. Guo, Yaxiao
    et al.
    Yao, Zhaoyang
    Zhan, Shaoqi
    Timmer, Brian J. J.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Li, Xiyu
    Xie, Zhen
    Meng, Qijun
    Fan, Lizhou
    Zhang, Fuguo
    Ahlquist, Mårten S. G.
    Cuartero, Maria
    Crespo, Gaston A.
    Sun, Licheng
    Molybdenum and boron synergistically boosting efficient electrochemical nitrogen fixation2020In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 78, article id 105391Article in journal (Refereed)
    Abstract [en]

    Ammonia production consumes-2% of the annual worldwide energy supply, therefore strategic alternatives for the energy-intensive ammonia synthesis through the Haber-Bosch process are of great importance to reduce our carbon footprint. Inspired by MoFe-nitrogenase and the energy-efficient and industrially feasible electrocatalytic synthesis of ammonia, we herein establish a catalytic electrode for artificial nitrogen fixation, featuring a carbon fiber cloth fully grafted by boron-doped molybdenum disulfide (B-MoS2/CFC) nanosheets. An excellent ammonia production rate of 44.09 mu g h(-1) cm(-2) is obtained at-0.2 V versus the reversible hydrogen electrode (RHE), whilst maintaining one of the best reported Faradaic efficiency (FE) of 21.72% in acidic aqueous electrolyte (0.1 M HCl). Further applying a more negative potential of-0.25 V renders the best ammonia production rate of 50.51 mu g h(-1) cm(-2). A strong-weak electron polarization (SWEP) pair from the different electron accepting and back-donating capacities of boron and molybdenum (2p shell for boron and 5d shell for molybdenum) is proposed to facilitate greatly the adsorption of non-polar dinitrogen gas via N equivalent to N bond polarization and the first protonation with large driving force. In addition, for the first time a visible light driven photo-electrochemical (PEC) cell for overall production of ammonia, hydrogen and oxygen from water + nitrogen, is demonstrated by coupling a bismuth vanadate BiVO4 photo-anode with the B-MoS2/CFC catalytic cathode.

  • 37.
    Hao, Wenming
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Björkman, Eva
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lilliestråle, Malte
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Activated carbons prepared from hydrothermally carbonized waste biomass used as adsorbents for CO22013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 526-532Article in journal (Refereed)
    Abstract [en]

    Activated carbons prepared from hydrothermally carbonized (HTC) waste biomass were studied with respect to the adsorption of carbon dioxide. The physically activated carbons (PAC) exhibited a large adsorption of CO2 of 1.45 mmol/g at a small partial pressure of CO2 (10 kPa and a temperature of 0 degrees C). These PACs were prepared by activation in a stream of CO2 and had significant amounts of ultramicropores, which were established by analyzing the adsorption of CO2 with a density functional theory. The uptake at such low pressures of CO2 is of most importance for an adsorption-driven CO2 capture from flue gas at large power stations, as it is difficult to imagine a pressurization of the flue gas. The capacities to adsorb CO2 of the different activated carbons were compared with both the micropore volumes as established by N-2 adsorption, and the ultramicropore volumes as established by CO2 adsorption. The ultramicropore volume is of crucial importance for the capture of CO2 from flue gas. PAC from HTC grass cuttings and from horse manure had the largest ultramicropore volumes. In general, the PAC showed excellent cyclability of adsorption/desorption of CO2 and a minimal capacity loss after subsequent cycles. In addition, the PAC showed a rapid adsorption of CO2. Both characteristics are essential for the eventual use of such PACs in the adsorption driven separation of CO2 from flue gas. A chemically activated carbon (CAC) was prepared by treating hydrothermally carbonized beer waste with H3PO4 and a heat treatment in a flow of N-2. This CAC showed a significant amount of mesopores in the range of 5 nm, in addition to micropores. The apparent selectivity for the activated carbons for CO2-over-N-2 adsorption was determined at 0 degrees C and 10 kPa.

  • 38.
    Hao, Wenming
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Björnerbäck, Fredrik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Trushkina, Yulia
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bengoechea, Mikel Oregui
    Salazar-Alvarez, German
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Barth, Tanja
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    High-Performance Magnetic Activated Carbon from Solid Waste from Lignin Conversion Processes. 1. Their Use As Adsorbents for CO22017In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 5, no 4, p. 3087-3095Article in journal (Refereed)
    Abstract [en]

    Lignin is naturally abundant and a renewable [GRAPHICS] precursor with the potential to be used in the production of both chemicals and materials. As many lignin conversion processes suffer from a significant production of solid wastes in the form of hydrochars, this study focused on transforming hydrochars into magnetic activated carbons (MAC). The hydrochars were produced via hydrothermal treatment of lignins together with formic acid. The activation of the hydrochars was performed chemically with KOH with a focus on the optimization of the MACs as adsorbents for CO2. MACs are potentially relevant to carbon capture and storage (CCS) and gas purification processes. In general, the MACs had high specific surface areas (up to 2875 m(2)/g), high specific pore volumes, and CO2 adsorption capacities of up to 6.0 mmol/g (I atm, 0 degrees C). The textual properties of the MACs depended on the temperature of the activation. MACs activated at a temperature of 700 degrees C had very high ultramicropore volumes, which are relevant for potential adsorption-driven separation of CO2 from N-2. Activation at 800 degrees C led to MACs with larger pores and very high specific surface areas. This temperature-dependent optimization option, combined with the magnetic properties, provided numerous potential applications of the MACs besides those of CCS. The hydrochar was derived from eucalyptus lignin, and the corresponding MACs displayed soft magnetic behavior with coercivities of <100 Oe and saturation magnetization values of 1-10 emu/g.

  • 39.
    He, Andong
    et al.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Wettlaufer, John
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Hertz beyond belief2014In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 10, no 13, p. 2264-2269Article in journal (Refereed)
    Abstract [en]

    We examine the validity of Hertz's linear elastic theory for central collisions of spheres using a viscoelastic model. This model explains why Hertz's theory is accurate in predicting the collision time and maximum contact area even when 40% of the kinetic energy is lost due to viscous dissipation. The main reason is that both the collision time and maximum contact area have a very weak dependence on the impact velocity. Moreover, we show that colliding objects exhibit an apparent size-dependent yield strength, which results from larger objects dissipating less energy at a given impact velocity.

  • 40. Hemmat, Zahra
    et al.
    Ahmadiparidari, Alireza
    Wang, Shuxi
    Kumar, Khagesh
    Zepeda, Michael
    Zhang, Chengji
    Dandu, Naveen
    Rastegar, Sina
    Majidi, Leily
    Jaradat, Ahmad
    Ngo, Anh
    Thornton, Katsuyo
    Curtiss, Larry A.
    Cabana, Jordi
    Huang, Zhehao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Salehi-Khojin, Amin
    Unprecedented Multifunctionality in 1D Nb1-xTaxS3 Transition Metal Trichalcogenide Alloy2022In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 32, no 34, article id 2205214Article in journal (Refereed)
    Abstract [en]

    1D materials, such as nanofibers or nanoribbons are considered as the future ultimate limit of downscaling for modern electrical and electrochemical devices. Here, for the first time, nanofibers of a solid solution transition metal trichalcogenide (TMTC), Nb1-xTaxS3, are successfully synthesized with outstanding electrical, thermal, and electrochemical characteristics rivaling the performance of the-state-of-the art materials for each application. This material shows nearly unchanged sheet resistance (≈740 Ω sq−1) versus bending cycles tested up to 90 cycles, stable sheet resistance in ambient conditions tested up to 60 days, remarkably high electrical breakdown current density of ≈30 MA cm−2, strong evidence of successive charge density wave transitions, and outstanding thermal stability up to ≈800 K. Additionally, this material demonstrates excellent activity and selectivity for CO2 conversion to CO reaching ≈350 mA cm−2 at −0.8 V versus RHE with a turnover frequency number of 25. It also exhibits an excellent performance in a high-rate Li–air battery with the specific capacity of 3000 mAh g−1 at a current density of 0.3 mA cm−2. This study uncovers the multifunctionality in 1D TMTC alloys for a wide range of applications and opens a new direction for the design of the next generation low-dimensional materials. 

  • 41. Huang, Guokai
    et al.
    Li, Teng
    Zhang, Xian
    Wang, Lingyu
    Cui, Daqing
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). China Institute of Atomic Energy, China.
    Yang, Miao
    Effects of Corrosion Products Deposited on 304 Stainless Steel on Reduction of Se (IV/VI) in Simulated Groundwater2022In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 8, article id 2705Article in journal (Refereed)
    Abstract [en]

    Selenium (Se) is a key mobile fission product in the geological disposal of nuclear waste. It is necessary to analyze the reductive deposition behavior of iron-based materials to Se(IV) and Se(VI) in groundwater. In the present work, the corrosion behavior of 304 stainless steel in simulated groundwater (SG) and the effects of corrosion products on the dissolution of Se were investigated by electrochemical and immersion tests. Experimental results revealed that passivation films formed on 304 stainless-steel samples were destroyed by polarization measurements, forming corrosion products consisting of Fe(II) compounds, such as Fe3O4 and FeO. Corrosion products deposited on the surface of steel samples previously treated by polarization measurements in SG + CaCl2/Na2CO3/Na2SiO3 solutions effectively reduced soluble Se(IV) and Se(VI) during immersion tests, depositing FeSe2 on sample surfaces.

  • 42. Huang, Qi
    et al.
    Zhao, Zhuyan
    Zhao, Xuhuan
    Li, Qi
    Liu, Hainan
    Lu, Heng
    Li, Qiuhong
    Du, Mao
    Cao, Yongjie
    Wang, Yang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Nanjing University of Science and Technology, China.
    Xu, Xuan
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhao, Deqiang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Chongqing Jiaotong University, China; Key Laboratory of Hydraulic and Waterway Engineering of the Ministry of Education, China; National Engineering Research Center for Inland Waterway Regulation, China.
    Effective photocatalytic sterilization based on composites of Ag/InVO4/BiOBr: Factors, mechanism and application2023In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 327, article id 125011Article in journal (Refereed)
    Abstract [en]

    We hypothesized that photocatalysts with a low band gap could be useful in the sterilization of ceramic tiles in the natural environments of toilets using natural light in those settings. Certain photocatalysts can produce reactive oxygen species (ROS) under light illumination, which in turn are bactericidal. The properties of the BiOBr-containing photocatalysts were tuned by creating junctions and heterostructures with Ag and InVO4 and studied with respect to their bactericidal effect in dispersion. The bactericidal mechanism was studied through experiments in which active species were captured and via electron paramagnetic resonance (EPR) spectroscopy. At an optimal dosage of 0.5 g/L, the Ag/InVO4/BiOBr composite had a sterilization efficacy of 99.9999 % in 30 min under visible light illumination of 1000 W. It retained a sterilization efficacy of 99.999 % after four cycles. Anions such as Cl, SO42−, and NO3 were shown to have no negative impact on sterilization efficacy. It was shown that the holes in the composite photocatalyst and hydroxyl radicals (·OH) were mechanistically critical for the sterilization. The photocatalysts were also studied in the field in the natural environment of a restroom, where they were loaded on ceramic tiles. Samples were collected from the surface of the ceramic tiles and analyzed for bacterial cultures and microbial diversity. The results were compared in the scope of the sterilization ability of various agents at the microbial level. The ceramic tiles loaded with Ag/InVO4/BiOBr showed the least amount of bacteria on their surfaces, and the microbial community richness was also the lowest.

  • 43. Ivanov, Mikhail F.
    et al.
    Kiverin, Alexey D.
    Liberman, Mikhail A.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Ignition of deflagration and detonation ahead of the flame due to radiative preheating of suspended micro particles2015In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 162, no 10, p. 3612-3621Article in journal (Refereed)
    Abstract [en]

    We study a flame propagating in the gaseous combustible mixture with suspended inert solid micro particles. The gaseous mixture is assumed to be transparent for thermal radiation emitted by the hot combustion products, while particles absorb and reemit the radiation. Thermal radiation heats the particles, which in turn transfer the heat to the surrounding unburned gaseous mixture by means of thermal heat transfer, so that the gas phase temperature lags that of the particles. We consider different scenarios depending on the spatial distribution of the particles, their size and the number density. In the case of uniform spatial distribution of the particles the radiation causes a modest increase of the temperature ahead of the flame and corresponding modest increase of the combustion velocity. In the case of non-uniform distribution of the particles (layered dust cloud), such that the particles number density is relatively small in the region just ahead of the flame front and increases in the distant regions ahead of the flame, the preheating caused by the thermal radiation may trigger additional independent source of ignition. Far ahead of the flame, where number density of particles increases forming a dense cloud of particles, the radiative preheating results in the formation of a temperature gradient with the maximum temperature sufficient for ignition. Depending on the steepness of the temperature gradient formed in the unburned mixture, either deflagration or detonation can be initiated via the Zel'dovich's gradient mechanism. The ignition and the resulting combustion regimes depend on the number density profile and, correspondingly, on the temperature profile (temperature gradient), which is formed in effect of radiation absorption and gas-dynamic expansion. The effect of radiation preheating as stronger as smaller is the normal flame velocity. The effect of radiation heat transfer in the case of coal dust flames propagating in layered particle-gas deposits cloud can result in the spread of combustion wave with velocity up to 1000 m/s and it is a plausible explanation of the origin of dust explosion in coal mines.

  • 44. Jalvo, Blanca
    et al.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Rosal, Roberto
    Coaxial poly(lactic acid) electrospun composite membranes incorporating cellulose and chitin nanocrystals2017In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 544, p. 261-271Article in journal (Refereed)
    Abstract [en]

    In this study, we used electrospinning to produce core-shell nanofibers of poly(lactic acid) as core and polyacrylonitrile/ cellulose nanocrystals (CNC) or polyacrylonitrile/chitin nanocrystals (ChNC) as shell. Electrospun materials prepared at different nanocrystal concentrations were tested and assayed as microfiltration membranes. The coaxial membranes presented a maximum pore size in the 1.2-2.6 mu m range and rejections > 85% for bacterial cells (0.5 x 2.0 mu m) and > 99% for fungal spores (> 2 mu m). The morphological and mechanical properties and the water permeability of the nanocomposite membranes were studied. The morphological characterization showed random fibers of beadless and well-defined core/shell structured fibers with diameter generally below the micron size with presence of secondary ultrafine nanofibers. Tensile strength and Young's modulus of elasticity improved with respect to coaxial membranes without nanocrystals with best mechanical properties achieved at 5 wt% CNC and 15 wt% ChNC loadings. The enhancement was attributed to the reinforcing effect of the percolating network of cellulose nanocrystals. Water permeability increased for all membranes loaded with nanocrystals with respect to the coaxial fibers without nanocrystals, the highest corresponding to ChNC composites with up to a 240% increase over non-loaded membranes. Composite membranes prepared with CNC in their shell were hydrophilic, in contrast with the hydrophobic PLA core, while coaxial fibers with ChNC were superhydrophilic. CNC membranes were negatively charged but ChNC originated neutral or positively charged membranes due to the contribution of deacetylated chitin structural units. Upon exposure to E. coli cultures, composite membranes containing ChNC showed a high antimicrobial action and were essentially free of bacterial colonization under strong biofilm formation conditions.

  • 45. Karim, Zoheb
    et al.
    Claudpierre, Simon
    Grahn, Mattias
    Oksman, Kristiina
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Nanocellulose based functional membranes for water cleaning: Tailoring of mechanical properties, porosity and metal ion capture2016In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 514, p. 418-428Article in journal (Refereed)
    Abstract [en]

    Multi-layered nanocellulose membranes were prepared using vacuum-filtration of cellulose nanofibers suspensions followed by dip coating with cellulose nanocrystals having sulphate or carboxyl surface groups. It was possible to tailor the specific surface area, pore structure, water flux and wet strength of the membranes via control of drying conditions and acetone treatment. Cellulose nanofibers coated with cellulose nanocrystal with carboxyl surface groups showed the highest tensile strength (95 MPa), which decreased in wet conditions (approximate to 3.7 MPa) and with acetone (2.7 MPa) treatment. The membrane pore sizes, determined by nitrogen adsorption/desorption were in nanofiltration range (74 angstrom) and the acetone treatment increased the average pore sizes to tight ultrafiltration range (194 angstrom) with a concomitant increase (7000%) of surface area. The water flux, also increased from zero to 25 L m(-2) h(-1) at a pressure differential of 0.45 MPa, for acetone treated membranes. Modeling of the permeance showed that the middle layer of cellulose nanofibers was responsible for the majority of the resistance to flux and the flux can be improved by increasing the porosity or decreasing the thickness of this layer. The membranes irrespective of the surface functionality showed exceptional capability (approximate to 100%) to remove Ag+, Cu2+ and Fe3+/Fe2+ ions from mirror industry effluents. Surface adsorption followed by micro-precipitation was considered as the possible mechanism of ion removal, which opens up a new generation of ultra filtration membranes with high rejection towards metal ions.

  • 46. Karim, Zoheb
    et al.
    Georgouvelas, Dimitrios
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Svedberg, Anna
    Monti, Susanna
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Upscaled engineered functional microfibrillated cellulose flat sheet membranes for removing charged water pollutants2022In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 289, article id 120745Article in journal (Refereed)
    Abstract [en]

    Polymeric composite membranes have shown great potential in removing pollutants from water. In the current study, flat sheet functional membranes of microfibrillated cellulose (MFC) with mixed and layered architectures are produced using the up-scaled Dynamic Sheet Former (Formette) in a fully water-based-system, and their potential for the removal of charged impurities is evaluated. The processing of composite membranes is unique in terms of their size (1 m × 20 cm), assembled MFC architectures, controlled/tunable porosity, functional groups densities, and free-standing at high water pressure. Such properties could be difficult to achieve with a lab-scale processing setup. It is shown that the MFC assembly has a direct influence on the pollutant removal efficiency, and again the layered architecture turns out to be a more efficient scavenger of the charged pollutants due to the combined actions of electrostatic interactions, hydrogen bonding, and size exclusion, which are responsible for an ultrafast separation of the impurities through the flat sheets membranes. These experimental results are supported by reactive molecular dynamics simulations of representative model systems that provided possible realistic scenarios at the atomic/molecular scale. All the data confirm the scalability and tunability of the produced MFC-based water cleaning membranes, which show high adsorption capacity, flexibility, hydrolytic stability, and mechanical robustness.

  • 47.
    Lebedeva, Daria
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hijmans, Samuel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Subbotina, Elena
    Stockholm University, Faculty of Science, Department of Organic Chemistry. KTH Royal Institute of Technology, Sweden.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Waste-to-Fuel Approach: Valorization of Lignin from Coconut Coir Pith2022In: ACS Agricultural Science and Technology, E-ISSN 2692-1952, Vol. 2, no 2, p. 349-358Article in journal (Refereed)
    Abstract [en]

    Coconut Coir Pith (CCP) is a relatively unexplored type of lignocellulosic waste from the coconut industry. As a feedstock that is highly enriched in lignin (Klason lignin content of 40.9 wt % found in this study), CCP is a potential source for renewable lignin-derived materials. We have performed a systematic study on the characterization and valorization of lignin from CCP. We have investigated two different valorization approaches: reductive catalytic fractionation (RCF) and soda pulping followed by catalytic hydrodeoxygenation. During RCF, the lignin was converted into monomeric products in 7.6 wt %. Using soda pulping conditions, we were able to isolate lignin from CCP in 74% yield. Subsequent hydrotreatment of the lignin over a Pt/MoO3/TiO2catalyst resulted in the formation of hydrogenated oil in 43 wt % yield, suitable for the production of biobased diesel fuels and lubricant base oils. 

  • 48. Li, Fangfang
    et al.
    Laaksonen, Aatto
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden; “Petru Poni”Institute of Macromolecular Chemistry, Romania; Nanjing Tech University, China.
    Zhang, Xiangping
    Ji, Xiaoyan
    Rotten Eggs Revaluated: Ionic Liquids and Deep Eutectic Solvents for Removal and Utilization of Hydrogen Sulfide2022In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 61, no 7, p. 2643-2671Article, review/survey (Refereed)
    Abstract [en]

    Hydrogen sulfide (H2S) is highly toxic and one of the problematic impurities in industrial gas streams, calling for H2S removal down to single-digit ppm levels to protect health and environment, and not to harm to the downstream processes. Here, we discuss the recent developments and challenges of current H2S removal technologies. Furthermore, we present a comprehensive review of H2S removal in ionic liquids (ILs), IL-based solvents/adsorbents/membranes, and deep eutectic solvents (DESs) due to their unique advantages. We analyze theoretical studies to better understand the microscopic details behind H2S removal. We discuss new research on IL/DES-based H2S removal processes from an industrial perspective. Finally, we summarize the utilization of H2S in IL/DES-based systems for the recovery of sulfur and hydrogen, and synthesis of value-added chemicals. This review will provide both general and in-depth knowledge of the achievements, difficulties, and research priorities in developing novel ILs/DESs for efficient and sustainable H2S removal and utilization.

  • 49. Li, Fangfang
    et al.
    Mocci, Francesca
    Zhang, Xiangping
    Ji, Xiaoyan
    Laaksonen, Aatto
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden; "Petru Poni" Institute of Macromolecular Chemistry, Romania; Nanjing Tech University, China.
    Ionic liquids for CO2 electrochemical reduction2021In: Chinese Journal of Chemical Engineering, ISSN 1004-9541, E-ISSN 2210-321X, Vol. 31, p. 75-93Article, review/survey (Refereed)
    Abstract [en]

    Electrochemical reduction of CO2 is a novel research field towards a CO2-neutral global economy and combating fast accelerating and disastrous climate changes while finding new solutions to store renewable energy in value-added chemicals and fuels. Ionic liquids (ILs), as medium and catalysts (or supporting part of catalysts) have been given wide attention in the electrochemical CO2 reduction reaction (CO2RR) due to their unique advantages in lowering overpotential and improving the product selectivity, as well as their designable and tunable properties. In this review, we have summarized the recent progress of CO2 electro-reduction in IL-based electrolytes to produce higher-value chemicals. We then have highlighted the unique enhancing effect of ILs on CO2RR as templates, precursors, and surface functional moieties of electrocatalytic materials. Finally, computational chemistry tools utilized to understand how the ILs facilitate the CO2RR or to propose the reaction mechanisms, generated intermediates and products have been discussed.

  • 50. Li, Peng-Fei
    et al.
    Yuan, Hua
    Cheng, Zi-Dong
    Qian, Li-Bing
    Liu, Zhong-Lin
    Jin, Bo
    Ha, Shuai
    Wan, Cheng-Liang
    Cui, Ying
    Ma, Yue
    Yang, Zhi-Hu
    Lu, Di
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Li, Ming
    Zhang, Hong-Qiang
    Chen, Xi-Meng
    低能电子在玻璃管中的稳定传输: [Stable transmission of low energy electrons in glass tube with outer surface grounded conductively shielding]2022In: Wuli xuebao, ISSN 1000-3290, Vol. 71, no 7, article id 074101Article in journal (Refereed)
    Abstract [en]

    The electron microbeam is useful for modifying certain fragments of biomolecule. It is successful to apply the guiding effect to making the microbeam of positively charged particles by using single glass capillary. However, the mechanism for the electron transport through insulating capillaries is unclear. Meanwhile, previous researches show that there are oscillations of the transmission intensity of electrons with time in the glass capillaries with outer serface having no grounded conductive shielding, So, the application of glass capillary to making the microbeam of electrons is limited. In this paper, the transmission of 1.5 and 0.9 keV electrons through the glass capillary without/with the grounded conductive-coated outer surface are investigated, respectively. This study aims to understand the mechanism for low energy electron transport in the glass capillaries, and find the conditions for the steady transport of the electrons. Two-dimensional angular distribution of the transported electrons and its time evolution are measured. It is found that the intensity of the transported electrons with the incident energy through the glass capillaries for the glass capillaries without and with the grounded conductive-coated outer surface show the typical geometrical transmission characteristics. The time evolution of the 1.5- keV electron transport presents an extremely complex variation for the glass capillary without the grounded conductive-coated outer surface. The intensity first falls, then rises and finally oscillates around a certain mean value. Correspondingly, the angular distribution center experiences moving towards positive-negative-settlement. In comparison, the charge-up process of the 0.9 keV electron transport through the glass capillary with the grounded conductive-coated outer surface shows a relatively simple behavior. At first, the intensity declines rapidly with time. Then, it slowly rises till a certain value and stays steady subsequently. The angular distribution of transported electrons follows the intensity distribution in general, but with some delay. It quickly moves to negative direction then comes back to positive direction. Finally, it regresses extremely slowly and ends up around the tilt angle. To better understand the physics behind the observed phenomena, the simulation for the interaction of the electrons with SiO2 material is performed to obtain the possible deposited charge distribution by the CASINO code. Based on the analysis of the experimental results and the simulated charge deposition, the conditions for stabilizing the electron transport through glass capillary are presented.

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