RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
From blue hydrochars to activated carbons: Hydrothermal carbonization, chemical activation and gas adsorption
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).ORCID-id: 0000-0001-8225-9670
2024 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Hydrothermal carbonization (HTC) of carbohydrates and biomass is a straightforward method for preparing hydrochars at low temperatures of 180-250 °C. Hydrochars are more carbonized than their precursors. Increasing the carbonization degree of hydrochars at hydrothermal temperatures is a scientific quest that is addressed in this thesis. Hydrochars are known to have a spherical or irregular morphology. Here we address thin film hydrochars for the first time.  Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for gas adsorption applications. In this thesis, enhanced adsorption of VOCs at low pressures is addressed by using iron phosphate impregnated activated carbons. Finaly, any chemical process or product including those in this thesis such as HTC, activation, hydrochar and activated carbons may contribute to the issue of environmental degradation positively or negatively. Such environmental impacts are addressed by life cycle assessment of processes of HTC and activation and their related products in the last paper of this thesis. Briefly mentioned, in my first study (Paper I), I focused on the HTC of glucose in the presence of iron (II) sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in the presence of iron (II) sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporosity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe (PO3)2 and it was shown that Fe (PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4-activated carbons were prepared and modified with FeS and FeSe and it was shown that the ACs were also impregnated with Fe2P, in the case of AC-FeS/Fe2P. FeSe and FeS were not detected by XRD. Only large crystals of Fe2P were detected in the sample AC-FeS/Fe2P. In the last study (Paper IV), prickly pear seed biomass from the agro sector in Tunisia was hydrothermally carbonized. The hydrochars were then activated into ACs by CO2 activation. The life cycle assessment of the HTC and activation process was investigated.  

Ort, förlag, år, upplaga, sidor
Department of Materials and Environmental Chemistry, Stockholm University , 2024. , s. 51
Nyckelord [en]
hydrochars, activated carbons, hydrothermal carbonization, chemical activation, gas adsorption
Nationell ämneskategori
Materialkemi
Forskningsämne
materialkemi
Identifikatorer
URN: urn:nbn:se:su:diva-228549ISBN: 978-91-8014-797-2 (tryckt)ISBN: 978-91-8014-798-9 (digital)OAI: oai:DiVA.org:su-228549DiVA, id: diva2:1853327
Disputation
2024-06-14, online via Zoom, public link is available at the department website, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2024-05-22 Skapad: 2024-04-22 Senast uppdaterad: 2024-05-13Bibliografiskt granskad
Delarbeten
1. Blue hydrochars formed on hydrothermal carbonization of glucose using an iron catalyst
Öppna denna publikation i ny flik eller fönster >>Blue hydrochars formed on hydrothermal carbonization of glucose using an iron catalyst
2022 (Engelska)Ingår i: Carbon Trends, ISSN 2667-0569, Vol. 8, artikel-id 100172Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We hypothesized that the morphology of the hydrochar from hydrothermal carbonization of glucose would be affected by Fe2+; and indeed, with such ions, large pieces of hydrochar formed that comprised aggregated spherical particles and blue and thin films. Thin carbonized films formed at the bottom of the autoclave liners or on TeflonTM tape used as a template. Free-standing films could be prepared by stretching the TeflonTM tape after the synthesis. The carbonized films that formed at the bottom of the autoclave adhered to spherical hydrochar particles. The blueness was ascribed to thin-film interference under white-light irradiation and related to the film thickness, which was about 200 nm. Analysis of transmission electron microscopy (TEM) images showed that the films consisted of a layered amorphous carbon. The amorphous and thin films were more carbonized than the amorphous carbon of the TEM grid, as derived via electron energy loss spectroscopy (EELS). Additional analysis of one of the thin films by X-ray photoelectron spectral analysis showed a higher carbon fraction than for bulk hydrochar, supporting the EELS analysis. We believe that the synthesis of thin films of hydrochar can open up new colloidal processing pathways, which could be useful in the preparation of carbon-based materials and alike.

Nyckelord
Hydrothermal carbonization, Glucose, Iron sulfate, Carbon spheres, Thin films, Thin film interference
Nationell ämneskategori
Materialkemi
Identifikatorer
urn:nbn:se:su:diva-206189 (URN)10.1016/j.cartre.2022.100172 (DOI)2-s2.0-85128535062 (Scopus ID)
Forskningsfinansiär
Mistra - Stiftelsen för miljöstrategisk forskning, 2015/31
Tillgänglig från: 2022-06-22 Skapad: 2022-06-22 Senast uppdaterad: 2024-04-22Bibliografiskt granskad
2. Adsorption of volatile organic compounds on activated carbon with included iron phosphate
Öppna denna publikation i ny flik eller fönster >>Adsorption of volatile organic compounds on activated carbon with included iron phosphate
Visa övriga...
2023 (Engelska)Ingår i: Carbon trends, ISSN 2667-0569, Vol. 11, artikel-id 100259Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Volatile organic compounds (VOCs) are often hazardous and need commonly to be removed from gas mixtures. Capture on activated carbon (AC) is one approach to achieving this. We hypothesized that the smallest pores on ACs and the inclusion of inorganic phosphates could enhance the low gas pressure uptake of two typical VOCs (acetone and isopropanol). To test this hypothesis, ACs were prepared by chemical activation of hydrochars with H3PO4 or a mixture of FeCl3 and H3PO4. The hydrochars had been prepared by hydrothermal carbonization of glucose. The ACs were characterized by XRD, IR, TGA, and the adsorption of N2, CO2, H2O, acetone, and isopropanol. The results showed that the ACs had comparably high adsorption of acetone and isopropanol at low vapor pressures. The low-pressure uptake (at 0.03 kPa) of isopropanol and acetone had values of up to 3.4 mmol/g and 2.2 mmol/g, respectively. This suggests that ACs containing iron phosphate could be of relevance for adsorption driven removal of VOC. It was also observed that the external surface area of the ACs containing iron phosphates increased upon secondary heat treatment in N2.

Nationell ämneskategori
Materialkemi
Identifikatorer
urn:nbn:se:su:diva-228544 (URN)10.1016/j.cartre.2023.100259 (DOI)001030948100001 ()2-s2.0-85151239392 (Scopus ID)
Forskningsfinansiär
Mistra - Stiftelsen för miljöstrategisk forskning, 2015/31Knut och Alice Wallenbergs Stiftelse
Tillgänglig från: 2024-04-22 Skapad: 2024-04-22 Senast uppdaterad: 2024-04-22Bibliografiskt granskad
3. Activated carbons impregnated with FeS/FeSe/Fe2P derived from hydrochars and chemical activation with H3PO4
Öppna denna publikation i ny flik eller fönster >>Activated carbons impregnated with FeS/FeSe/Fe2P derived from hydrochars and chemical activation with H3PO4
Visa övriga...
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Nationell ämneskategori
Materialkemi
Identifikatorer
urn:nbn:se:su:diva-228546 (URN)
Tillgänglig från: 2024-04-22 Skapad: 2024-04-22 Senast uppdaterad: 2024-04-22
4. Activated Carbons Produced from Hydrothermally Carbonized Prickly Pear Seed Waste
Öppna denna publikation i ny flik eller fönster >>Activated Carbons Produced from Hydrothermally Carbonized Prickly Pear Seed Waste
Visa övriga...
2022 (Engelska)Ingår i: Sustainability, E-ISSN 2071-1050, Vol. 14, nr 21, artikel-id 14559Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The agro-sector generates organic waste of various kinds, which potentially could be used to prepare functional materials, lessen environmental problems, and enhance circularity. In this context, the hypothesis that was put forward in this work is that prickly pear seed waste from the Tunisian agro-food industry could be used to prepare activated carbons. The prickly pear seed waste was first hydrothermally carbonized and the resulting hydrochar was activated in CO2 at 800 °C. The yield of the hydrothermal carbonization process is of importance, and it was the highest at intermediate dwell times and temperatures, which was ascribed to the re-precipitation of hydrochar particles on the heat-treated biomass. The hydrochars and activated carbons were characterized with scanning electron microscopy, thermogravimetry, Raman spectroscopy, and N2 and CO2 adsorption/desorption analyses. The activated carbons had micro- (<2 nm) and mesopores (2–50 nm), and specific surface areas and total pore volumes of about 400 m2 −1 and 0.21 cm3 g−1. The study showed that the prickly pear seed waste could be effectively transformed into both hydrochars and activated carbons and that is advisable to optimize the hydrothermal process for the mass yield. A life cycle analysis was performed to assess the environmental impact of the production of typical activated carbons using the approach of this study. Further studies could be focused on enhancing the properties of the activated carbons by further optimization of the activation process.

Nyckelord
bio-waste, prickly pear seeds, hydrothermal carbonization, activated carbons, CO2 activation, life cycle assessment, Green & Sustainable Science & Technology
Nationell ämneskategori
Geovetenskap och miljövetenskap
Identifikatorer
urn:nbn:se:su:diva-212591 (URN)10.3390/su142114559 (DOI)000885860700001 ()
Tillgänglig från: 2022-12-13 Skapad: 2022-12-13 Senast uppdaterad: 2024-04-22Bibliografiskt granskad

Open Access i DiVA

From blue hydrochars to activated carbons(2695 kB)126 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 2695 kBChecksumma SHA-512
2d1cab9ed06b1c0f9e7d3aac1f2918818ea81f273c33fa2b2a9dd2a9c7e80d0d66b0d227becdf148857e5fd0daed881b6e184d7195fe83a7bc59786e34405573
Typ fulltextMimetyp application/pdf

Person

Saadattalab, Vahid

Sök vidare i DiVA

Av författaren/redaktören
Saadattalab, Vahid
Av organisationen
Institutionen för material- och miljökemi (MMK)
Materialkemi

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 126 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

isbn
urn-nbn

Altmetricpoäng

isbn
urn-nbn
Totalt: 948 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf