We reported on the development of mesoporous zirconium hydroxide (mp-Zr(OH)4) sorbents with high capacity for adsorptive removal of organic pollutants from industrial wastewater. The sorbent was prepared by a one-step chemical precipitation method at room temperature. The adsorption capacity and removal efficiency for the chemical oxygen demand (COD) of the industrial wastewater were studied using an automatic adsorption measurement apparatus. The effects of different parameters (adsorbent dosage, adsorption time, regeneration times, adsorbate's molecular weight and adsorbate solubility), isotherm, thermodynamics, and kinetics were evaluated. By analyzing scanning electron microscopy (SEM) images and powder X-ray diffractograms (XRD) no obvious differences were observed for the sorbents before and after the adsorption of the organics, which indicated a structural stability of the sorbent. The specific surface area was reduced from 450 m2/g to 189 m2/g on adsorption, and after desorption of the organics the specific surface area was 350 m2/g. The adsorption of COD was analyzed in a Langmuir model that described the data better than the empirical Freundlich model. This finding points towards that the adsorption occurred as a monolayer on the mp-Zr(OH)4. The free energy of adsorption (ΔG) is in the range of −20 kJ/mol < ΔG < 0. Entropy changes are ΔS > 0. The kinetics of the adsorption of COD is better described with a Quasi-second-order dynamic model than with a Quasi-first-order dynamic model, which elucidates its primary reliance on porous adsorption surfaces and incorporation of chemical adsorption.

Microporous organic polymers that have three-dimensional connectivity stemming from monomers with tetrahedral or tetrahedron-like geometry can have high surface areas and strong fluorescence. There are however few examples of such polymers based on hindered biaryls, and their fluorescence has not been studied. Hypothesizing that the contortion in a hindered biphenyl moiety would modulate the optical properties of a polymer built from it, we synthesized a meta-enchained polyphenylene from a 2,2ʹ,6,6ʹ-tetramethylbiphenyl-based monomer, in which the two phenyl rings are nearly mutually perpendicular. The polymer was microporous with S_BET = 495 m² g⁻¹. The polymer absorbed near-UV light and emitted blue fluorescence despite the meta-enchainment that would have been expected to break the conjugation. A related copolymer, synthesized from 2,2ʹ,6,6ʹ-tetramethylbiphenyl-based and unsubstituted biphenyl-based monomers, was microporous but not fluorescent.

Given the substantial emissions of CO2 into the atmosphere, there is a critical need for effective CO2 adsorbents at scale, ideally derived from abundant and sustainable natural resources. In this work, microcrystalline cellulose derived from cotton is used to fabricate cellulose aerogel as porous support via a NaOH/urea-based dissolution and regeneration process, followed by surface modification with a series of amino silane coupling agents to produce aminated cellulose aerogel as CO2 adsorbent. The as-synthesized optimal adsorbent exhibits a high CO2 sorption capacity of up to 1.5 and 1.3 mmol g−1 at 0 °C and 25 °C at 1 bar, respectively. Notably, in-depth analysis shows that the adsorbent achieves an impressive capacity of CO2 uptake of 0.29 mmol g−1 at 25 °C at an exceptionally low CO2 pressure of 0.4 mbar, i.e., under ambient CO2 pressure. It implies its potential use as adsorbent both for the traditional point-source capture and the direct air capture as an emerging negative emission technology. This study underscores the environmentally friendly, cost-effective, and biosourced attributes of aminated cellulose aerogel as a compelling alternative for carbon capture, contributing to global initiatives combating CO2 emissions and stressing the key role of sustainable materials in tackling this global environmental challenge.

In nature, chirality transfer refines biomolecules across all size scales, bestowing them with a myriad of sophisticated functions. Despite recent advances in replicating chirality transfer with biotic or abiotic building blocks, a molecular understanding of the underlying mechanism of chirality transfer remains a daunting challenge. In this paper, the coassembly of two types of glycopeptide molecules differing in capability of forming intermolecular hydrogen bonds enabled the involvement of discontinuous hydrogen bond, which allowed for a nanoscale chirality transfer from glycopeptide molecules to chiral micelles, yet inhibited the micrometer scale chirality transfer toward helix formation, leading to an achiral transfer from chiral micelles to planar monolayer. Upon stacking the monolayer into a bilayer, the nonsuperimposable front and back faces of the chiral micelles involved in the monolayer ribbons lead to the opposite rotation of two layers toward increasing the continuity of H-bonds. The resultant continuity triggered the symmetry breaking of stacked bilayers and thus reactivated the micrometer-scale chirality transfer toward the final helix. This work delineates a promising step toward a better understanding and replicating the naturally occurring chirality transfer events and will be instructive to future chiral material design.

Sulfur (S) vacancies in metal sulfides are of interest in electrocatalysis and photoelectronics, but their effect on the generation of reactive oxygen species (ROS) during mechanical catalysis is unclear. This study investigates the impact of S-vacancies in defective bismuth sulfide (Bi2S3-x) on ROS production under ultrasonic irradiation and organic contaminant decomposition. S-vacancies disrupt the centrosymmetric structure of intrinsic Bi2S3, inducing piezoelectric effects and enhancing the electrical energy in Bi2S3-x. The positively charged S-vacancies in Bi2S3-x promote the separation of ultrasound-activated electron-hole pairs by capturing electrons. As a result, the optimal rate of H2O2 formation and the reaction rate constant for degrading Rhodamine B dye on Bi2S3-x are found to be 1.9 and 37 times higher, respectively, than those on Bi2S3 under ultrasonic irradiation. The nonzero catalytic efficiency in centrosymmetric Bi2S3 is due to the flexoelectric catalytic effect from nonuniform strain. These results guide the piezocatalyst design and elucidate mechanical catalysis mechanisms.

Tuning the charge transfer processes through a built-in electric field is an effective way to accelerate the dynamics of electro- and photocatalytic reactions. However, the coupling of the built-in electric field of p–n heterojunctions and the microstrain-induced polarization on the impact of piezocatalysis has not been fully explored. Herein, we demonstrate the role of the built-in electric field of p-type BiOI/n-type BiVO₄ heterojunctions in enhancing their piezocatalytic behaviors. The highly crystalline p–n heterojunction is synthesized by using a coprecipitation method under ambient aqueous conditions. Under ultrasonic irradiation in water exposed to air, the p–n heterojunctions exhibit significantly higher production rates of reactive species (·OH, ·O₂^–, and ¹O₂) as compared to isolated BiVO₄ and BiOI. Also, the piezocatalytic rate of H₂O₂ production with the BiOI/BiVO₄ heterojunction reaches 480 μmol g^–1 h^–1, which is 1.6- and 12-fold higher than those of BiVO₄ and BiOI, respectively. Furthermore, the p–n heterojunction maintains a highly stable H₂O₂ production rate under ultrasonic irradiation for up to 5 h. The results from the experiments and equation-driven simulations of the strain and piezoelectric potential distributions indicate that the piezocatalytic reactivity of the p–n heterojunction resulted from the polarization intensity induced by periodic ultrasound, which is enhanced by the built-in electric field of the p–n heterojunctions. This study provides new insights into the design of piezocatalysts and opens up new prospects for applications in medicine, environmental remediation, and sonochemical sensors. 

Pore size distribution is a key parameter in the performance of biobased pyrolytic char in novel applications. In industrial-scale production, the size of feedstock particles typically exceeds a few millimeters. For such particle sizes, it is a challenge to tailor the final properties of the char based only on the process conditions (experimental and modeling-wise). Pyrolysis studies of single particles larger than a few millimeters provide data sets useful for modeling and optimization of the process. Part 1 of this research focused on the pyrolysis of single particles of beech wood, secondary cracking, and its effect on the char porous texture. It contains a quantitative assessment of the effects of five conversion temperatures (from 300 to 840 °C) and two particle dimensions (Ø8 × 10 mm and Ø8 × 16 mm) on the composition of the pyrolysis vapors and pore morphology of the char. Results from real-time temperature and mass changes are presented along with release profiles of 15 vapor constituents measured by infrared spectroscopy. Furthermore, characterization of the collected bio-oil (using GC-MS/FID) and the textural hierarchical structured char (through N₂ and CO₂ adsorption, Hg porosimetry, and scanning electron microscopy (SEM)) was performed. Cracking of vapors above 500 °C was compound-specific. The polyaromatic hydrocarbons (PAHs) yield, between 680 and 840 °C, increased 5 times for 10 mm particles and 9 times for 16 mm ones. Besides temperature, PAH yield was suspected to correlate with particle length and PAHs/soot deposition in the micropores. Results showed that the macropores accounted for over 80% of the total pore volume, regardless of the temperature and particle length. Increasing the particle length by 60% caused a reduction in the specific surface area (ca. 15% at 840 °C) of the resulting char, mainly due to a reduction in microporosity. Based on the findings, the production conditions for a specific char application are suggested. The obtained data will be used in Part 2 of this research, devoted to subsequent CFD modeling of the process.

Waste plastics bring about increasingly serious environmental challenges, which can be partly addressed by their interconversion into valuable compounds. It is hypothesized that the porosity and acidity of a zeolite-based catalyst will affect the selectivity and effectiveness, enabling a controllable and selective conversion of polyethylene (PE) into gas-diesel or lubricating base oil. A series of embryonic, partial- and well-crystalline zeolites beta with adjustable porosity and acidity are prepared from mesoporous SBA-15. The catalysts and catalytic systems are studied with nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and adsorption kinetics and catalytic reactions. The adjustable porosity and acidity of zeolite-beta-based catalysts achieve a controllable selectivity toward gas-diesel or lubricating base oil for PE cracking. With a catalyst with mesopores and appropriate acid sites, a fast escape and reduced production of cracking of intermediates are observed, leading to a significant fraction (88.7%) of lubricating base oil. With more micropores, a high acid density, and strong acid strength, PE is multiply cracked into low carbon number hydrocarbons. The strong acid center of the zeolite is confirmed to facilitate significantly the activation of hydrogen (H2), and, an in situ ammonia poisoning strategy can significantly inhibit hydrogen transfer and effectively regulate the product distribution.

Sustainable composite materials, including carnauba wax, can store energy in the form of latent heat, and containing the wax may allow form-stable melting and crystallization cycles to be performed. Here, it is shown that carnauba wax in the molten state and the abundant nanoclay montmorillonite form stable composites with mass ratios of 50–70% (w/w). Transmission electron microscopy analysis reveals the inhomogeneous distribution of the nanoclay in the wax matrix. Analyses with infrared and multinuclear solid-state nuclear magnetic resonance (NMR) spectroscopy prove the chemical inertness of the composite materials during preparation. No new phases are formed according to studies with powder X-ray diffraction. The addition of the nanoclay increases the thermal conductivity and prevents the leakage of the phase change material, as well as reducing the time intervals of the cycle of accumulation and the return of heat. The latent heat increases in the row 69.5 ± 3.7 J/g, 95.0 ± 2.5 J/g, and 107.9 ± 1.7 J/g for the composite materials containing resp. 50%, 60% and 70% carnauba wax. Analysis of temperature-dependent 13C cross-polarization solid-state NMR spectra reveal the enhanced amorphization and altered molecular dynamics of the carnauba wax constituents in the composite materials. The amorphization also defines changes in the thermal transport mechanism in the composites compared to pure wax at elevated temperatures.

Mesoporous silica particles (MSPs) have been studied for their potential therapeutic uses in controlling obesity and diabetes. Previous studies have shown that the level of digestion of starch by α-amylase is considerably reduced in the presence of MSPs, and it has been shown to be caused by the adsorption of α-amylase by MSPs. In this study, we tested a hypothesis of enzymatic deactivation and measured the activity of α-amylase together with MSPs (SBA-15) using comparably small CNP-G3 (2-chloro-4-nitrophenyl alpha-d-maltotrioside) as a substrate. We showed that pore-incorporated α-amylase was active and displayed higher activity and stability compared to amylase in solution (the control). We attribute this to physical effects: the coadsorption of CNP-G3 on the MSPs and the relatively snug fit of the amylase in the pores. Biosorption in this article refers to the process of removal or adsorption of α-amylase from its solution phase into the same solution dispersed in, or adsorbed on, the MSPs. Large quantities of α-amylase were biosorbed (about 21% w/w) on the MSPs, and high values of the maximum reaction rate (V_max) and the Michaelis–Menten constant (K_M) were observed for the enzyme kinetics. These findings show that the reduced enzymatic activity for α-amylase on MSP observed here and in earlier studies was related to the large probe (starch) being too large to adsorb in the pores, and potato starch has indeed a hydrodynamic diameter much larger than the pore sizes of MSPs. Further insights into the interactions and environments of the α-amylase inside the MSPs were provided by ¹H fast magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and ¹³C/¹⁵N dynamic nuclear polarization MAS NMR experiments. It could be concluded that the overall fold and solvation of the α-amylase inside the MSPs were nearly identical to those in solution.