Revealing Photocatalytic Performance of ZnxCd1-xS Nanoparticles Depending on the Irradiation Wavelength

Photocatalysts are useful for various applications, including the conservation and storage of energy, wastewater treatment, air purification, semiconductors, and production of high-value-added products. Herein, Zn_xCd_1-xS nanoparticle (NP) photocatalysts with different concentrations of Zn²⁺ ions (x = 0.0, 0.3, 0.5, or 0.7) were successfully synthesized. The photocatalytic activities of Zn_xCd_1-xS NPs varied with the irradiation wavelength. X-ray diffraction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and ultraviolet-visible spectroscopy were used to characterize the surface morphology and electronic properties of the Zn_xCd_1-xS NPs. In addition, in situ X-ray photoelectron spectroscopy was performed to investigate the effect of the concentration of Zn²⁺ ions on the irradiation wavelength for photocatalytic activity. Furthermore, wavelength-dependent photocatalytic degradation (PCD) activity of the Zn_xCd_1-xS NPs was investigated using biomass-derived 2,5-hydroxymethylfurfural (HMF). We observed that the selective oxidation of HMF using Zn_xCd_1-xS NPs resulted in the formation of 2,5-furandicarboxylic acid via 5-hydroxymethyl-2-furancarboxylic acid or 2,5-diformylfuran. The selective oxidation of HMF was dependent on the irradiation wavelength for PCD. Moreover, the irradiation wavelength for the PCD depended on the concentration of Zn²⁺ ions in the Zn_xCd_1-xS NPs.

Red anatase TiO2 microspheres with exposed major {001} facets and boron-stabilized hydrogen-occupied oxygen vacancies for visible-light-responsive water oxidation

In pursuit of efficient solar energy to chemical energy conversion through band engineering of wide-bandgap photocatalysts such as TiO₂, a compromise occurs between a narrow bandgap and high-redox-capacity photo-induced charge carriers, which impairs the potential advantages associated with the widened absorption range. The key to this compromise is an integrative modifier that can simultaneously modulate both the bandgap and band edge positions. Herein, we theoretically and experimentally demonstrate that oxygen vacancies occupied by boron-stabilized hydrogen pairs (OV_BH) serve as an integrative band modifier. Compared to hydrogen-occupied oxygen vacancies (OV_H), which require the aggregation of nanosized anatase TiO₂ particles, oxygen vacancies coupled with boron (OV_BH) can be easily introduced into large and highly crystalline TiO₂ particles, as shown by density functional theory (DFT) calculations. The coupling with interstitial boron facilitates the introduction of paired hydrogen atoms. The red-colored {001} faceted anatase TiO₂ microspheres with OV_BH benefit from the narrowed bandgap of 1.84 eV and the down-shifted band position. These microspheres not only absorb long-wavelength visible light up to 674 nm but also enhance visible-light-driven photocatalytic oxygen evolution.

Lignin C-C bond cleavage induced by consecutive two-photon excitation of a metal-free photocatalyst

Photocatalytic lignin valorization has caught widespread attention; yet the reaction systems often employ noble metal complexes, hydrogen atom transfer (HAT) agents, and/or sacrificial electron donors/acceptors that do not comply with atom economy or environmental friendliness. Herein, we discovered that N-phenylphenothiazine (PTH) as a metal-free photocatalyst induced the cleavage of the lignin C_α-C_β bond under ambient conditions free of those additional agents with a high yield and selectivity toward benzoic acid. Transient spectroscopic investigations revealed that the energy-demanding C_α-C_β bond cleavage was induced by the potent oxidant, ²PTH˙⁺*, that was derived from consecutive two-photon excitation of PTH.

Recent Advances in Lignocellulose-Based Monomers and Their Polymerization

Replacing fossil-based polymers with renewable bio-based polymers is one of the most promising ways to solve the environmental issues and climate change we human beings are facing. The production of new lignocellulose-based polymers involves five steps, including (1) fractionation of lignocellulose into cellulose, hemicellulose, and lignin; (2) depolymerization of the fractionated cellulose, hemicellulose, and lignin into carbohydrates and aromatic compounds; (3) catalytic or thermal conversion of the depolymerized carbohydrates and aromatic compounds to platform chemicals; (4) further conversion of the platform chemicals to the desired bio-based monomers; (5) polymerization of the above monomers to bio-based polymers by suitable polymerization methods. This review article will focus on the progress of bio-based monomers derived from lignocellulose, in particular the preparation of bio-based monomers from 5-hydroxymethylfurfural (5-HMF) and vanillin, and their polymerization methods. The latest research progress and application scenarios of related bio-based polymeric materials will be also discussed, as well as future trends in bio-based polymers.

Precisely Constructed Metal Sulfides with Localized Single-Atom Rhodium for Photocatalytic C-H Activation and Direct Methanol Coupling to Ethylene Glycol

Although there are many studies on photocatalytic environmental remediation, hydrogen evolution, and chemical transformations, less success has been achieved for the synthesis of industrially important and largely demanded bulk chemicals using semiconductor photocatalysis, which holds great potential to drive unique chemical reactions that are difficult to implement by the conventional heterogeneous catalysis. The performance of semiconductors used for photochemical synthesis is, however, usually unsatisfactory due to limited efficiencies in light harvesting, charge-carrier separation, and surface reactions. The precise construction of heterogeneous photocatalysts to facilitate these processes is an attractive but challenging goal. Here, single-atom rhodium-doped metal sulfide nanorods composed of alternately stacked wurtzite/zinc-blende segments are successfully designed and fabricated, which demonstrate record-breaking efficiencies for visible light-driven preferential activation of C-H bond in methanol to form ethylene glycol (EG), a key bulk chemical used for the production of polyethylene terephthalate (PET) polymer. The wurtzite/zinc-blende heterojunctions lined regularly in one dimension accelerate the charge-carrier separation and migration. Single-atom rhodium selectively deposited onto the wurtzite segment with photogenerated holes accumulated facilitates methanol adsorption and C-H activation. The present work paves the way to harnessing photocatalysis for bulk chemical synthesis with structure-defined semiconductors.

Concurrent production of ferulic acid and glucose from wheat bran by catalysis of a putative bifunctional enzyme

The aim of this work is to study a bifunctional endoglucanase/carboxylesterase in Sphingobacterium soilsilvae Em02 and express it in soluble form in engineered Escherichia coli. The molecular weight of the recombinant protein of the bifunctional enzyme was 41 KDa. This research also determined the enzymatic activities of the bifunctional enzymes using microcrystalline cellulose and p-nitrophenyl butyrate as substrates and found 40 °C as the optimum temperature for their enzymatic activities. The optimal pH in dual function was 6.0 for endoglucanase and 7.0 for carboxylesterase. The bifunctional enzyme also exhibited enzymatic activities on the natural biomass by generating up to 3.94 mg of glucose and 49.4 μg of ferulic acid from 20 mg of destarched wheat bran. This indicates the broad application prospects of the bifunctional enzyme in agriculture and industry.

Photocatalytic Depolymerization of Native Lignin toward Chemically Recyclable Polymer Networks

As an inedible component of biomass, lignin features rich functional groups that are desired for chemical syntheses. How to effectively depolymerize lignin without compromising the more valuable cellulose and hemicellulose has been a significant challenge. Existing biomass processing procedures either induce extensive condensation in lignin that greatly hinders its chemical utilization or focus on fully depolymerizing lignin to produce monomers that are difficult to separate for subsequent chemical synthesis. Here, we report a new approach to selective partial depolymerization, which produces oligomers that can be readily converted to chemically recyclable polymer networks. The process takes advantage of the high selectivity of photocatalytic activation of the β-O-4 bond in lignin by tetrabutylammonium decatungstate (TBADT). The availability of exogenous electron mediators or scavengers promotes cleavage or oxidation of this bond, respectively, enabling high degrees of control over the depolymerization and the density of a key functional group, C=O, in the products. The resulting oligomers can then be readily utilized for the synthesis of polymer networks through reactions between C=O and branched -NH₂ as a dynamic covalent cross-linker. Importantly, the resulting polymer network can be recycled to enable a circular economy of materials directly derived from biomass.

Chitosan as an Outstanding Polysaccharide Improving Health-Commodities of Humans and Environmental Protection

Public health, production and preservation of food, development of environmentally friendly (cosmeto-)textiles and plastics, synthesis processes using green technology, and improvement of water quality, among other domains, can be controlled with the help of chitosan. It has been demonstrated that this biopolymer exhibits advantageous properties, such as biocompatibility, biodegradability, antimicrobial effect, mucoadhesive properties, film-forming capacity, elicitor of plant defenses, coagulant-flocculant ability, synergistic effect and adjuvant along with other substances and materials. In part, its versatility is attributed to the presence of ionizable and reactive primary amino groups that provide strong chemical interactions with small inorganic and organic substances, macromolecules, ions, and cell membranes/walls. Hence, chitosan has been used either to create new materials or to modify the properties of conventional materials applied on an industrial scale. Considering the relevance of strategic topics around the world, this review integrates recent studies and key background information constructed by different researchers designing chitosan-based materials with potential applications in the aforementioned concerns.

Direct Photocatalytic Synthesis of Acetic Acid from Methane and CO at Ambient Temperature Using Water as Oxidant

Direct functionalization of methane selectively to value-added chemicals is still one of the main challenges in modern science. Acetic acid is an important industrial chemical produced nowadays by expensive and environmentally unfriendly carbonylation of methanol using homogeneous catalysts. Here, we report a new photocatalytic reaction route to synthesize acetic acid from CH₄ and CO at room temperature using water as the sole external oxygen source. The optimized photocatalyst consists of a TiO₂ support and ammonium phosphotungstic polyoxometalate (NPW) clusters anchored with isolated Pt single atoms (Pt₁). It enables a stable synthesis of 5.7 mmol·L^-1 acetic acid solution in 60 h with the selectivity over 90% and 66% to acetic acid on liquid-phase and carbon basis, respectively, with the production of 99 mol of acetic acid per mol of Pt. Combined isotopic and in situ spectroscopy investigation suggests that synthesis of acetic acid proceeds via a photocatalytic oxidative carbonylation of methane over the Pt₁ sites, with the methane activation facilitated by water-derived hydroxyl radicals.

Integrating 1G with 2G Bioethanol Production by Using Distillers’ Dried Grains with Solubles (DDGS) as the Feedstock for Lignocellulolytic Enzyme Production

First-generation (1G) bioethanol is one of the most used liquid biofuels in the transport industry. It is generated by using sugar- or starch-based feedstocks, while second-generation (2G) bioethanol is generated by using lignocellulosic feedstocks. Distillers’ dried grains with solubles (DDGS) is a byproduct of first-generation bioethanol production with a current annual production of 22.6 million tons in the USA. DDGS is rich in fiber and valuable nutrients contents, which can be used to produce lignocellulolytic enzymes such as cellulases and hemicellulases for 2G bioethanol production. However, DDGS needs a pretreatment method such as dilute acid, ammonia soaking, or steam hydrolysis to release monosaccharides and short-length oligosaccharides as fermentable sugars for use in microbial media. These fermentable sugars can then induce microbial growth and enzyme production compared to only glucose or xylose in the media. In addition, selection of one or more suitable microbial strains, which work best with the DDGS for enzyme production, is also needed. Media optimization and fermentation process optimization strategies can then be applied to find the optimum conditions for the production of cellulases and hemicellulases needed for 2G bioethanol production. Therefore, in this review, a summary of all such techniques is compiled with a special focus on recent findings obtained in previous pieces of research conducted by the authors and by others in the literature. Furthermore, a comparison of such techniques applied to other feedstocks and process improvement strategies is also provided. Overall, dilute acid pretreatment is proven to be better than other pretreatment methods, and fermentation optimization strategies can enhance enzyme production by considerable folds with a suitable feedstock such as DDGS. Future studies can be further enhanced by the technoeconomic viability of DDGS as the on-site enzyme feedstock for the manufacture of second-generation bioethanol (2G) in first-generation (1G) ethanol plants, thus bridging the two processes for the efficient production of bioethanol using corn or other starch-based lignocellulosic plants.

Selective Photocatalytic Transformation of Lignin to Aromatic Chemicals by Crystalline Carbon Nitride in Water-Acetonitrile Solutions

The photocatalytic conversion of lignin to aromatic compounds in aqueous solutions is a promising approach. We herein report a crystalline carbon nitride prepared by high-temperature thermal polymerization and alkali-metal molten salt treatment, which was then applied in the selective conversion of lignin to aromatic compounds. The results showed that the tri-s-tri-C₃N₄ presented a relatively high activity and selectivity for the conversion of lignin in aqueous solutions. In a 95% water-acetonitrile solution, it achieved a relatively high conversation rate of lignin, reaching 62.00%, and the selectivity of the C-C bond cleavage was high, at 86.8%. The characterization results obtained by TEM, UV-vis/DRS, PL, and transient photocurrent response showed that the ultra-high activity of tri-s-tri-C₃N₄ was mainly due to the improvements in crystallinity and light absorption. Mechanism studies showed that the dispersion of the catalyst and the combination of lignin and catalyst in aqueous solvents with different acetonitrile ratios were the main factors affecting lignin conversion. As the water content in the solutions increased, the primary active sites were converted from h⁺ to ·O₂^-. This study revealed the interactions between lignin, photocatalysts, and reaction solutions, providing a theoretical basis for the photocatalytic conversion of lignin in aqueous solutions.

Collagen Fiber-Based Advanced Separation Materials: Recent Developments and Future Perspectives

Separation plays a critical role in a broad range of industrial applications. Developing advanced separation materials is of great significance for the future development of separation technology. Collagen fibers (CFs), the typical structural proteins, exhibit unique structural hierarchy, amphiphilic wettability, and versatile chemical reactivity. These distinctive properties provide infinite possibilities for the rational design of advanced separation materials. During the past 2 decades, many progressive achievements in the development of CFs-derived advanced separation materials have been witnessed already. Herein, the CFs-based separation materials are focused on and the recent progresses in this topic are reviewed. CFs widely existing in animal skins display unique hierarchically fibrous structure, amphiphilicity-enabled surface wetting behaviors, multi-functionality guaranteed covalent/non-covalent reaction versatility. These outstanding merits of CFs bring great opportunities for realizing rational design of a variety of advanced separation materials that were capable of achieving high-performance separations to diverse specific targets, including oily pollutants, natural products, metal ions, anionic contaminants and proteins, etc. Besides, the important issues for the further development of CFs-based advanced separation materials are also discussed.

Visible Light-Induced Deoxygenation and Allylation/Vinylation of Pyridyl Ethers

The generation of alkyl radicals by deoxygenation of unactivated ethers under visible light catalysis is a hitherto unmet challenge. Herein, we report a visible light-induced deoxygenation of pyridyl ethers via formation of their pyridinium salts. The generated benzylic radicals further react with allyl/alkenyl sulfones to provide a series of coupling products in good to moderate yields. This process is proposed to undergo a reductive quenching cycle, which was elucidated by chemical, optical, and electrical experiments.

Waste Biomass Selective and Sustainable Photooxidation to High-Added-Value Products: A Review

Researchers worldwide seek to develop convenient, green, and ecological production processes to synthesize chemical products with high added value. In this sense, lignocellulosic biomass photocatalysis is an excellent process for obtaining various outcomes for the industry. One issue of biomass transformation via heterogeneous catalysis into valuable chemicals is the selection of an adequate catalyst that ensures high conversion and selectivity at low costs. Titanium oxide (TiO2), is widely used for several applications, including photocatalytic biomass degradation, depolymerization, and transformation. Graphite carbon nitride (g-C3N4) is a metal-free polymeric semiconductor with high oxidation and temperature resistance and there is a recent interest in developing this catalyst. Both catalysts are amenable to industrial production, relatively easy to dope, and suited for solar light absorption. Recent investigations also show the advantages of using heterojunctions, for biomass derivates production, due to their better solar spectrum absorption properties and, thus, higher efficiency, conversion, and selectivity over a broader spectrum. This work summarizes recent studies that maximize selectivity and conversion of biomass using photocatalysts based on TiO2 and g-C3N4 as supports, as well as the advantages of using metals, heterojunctions, and macromolecules in converting cellulose and lignin. The results presented show that heterogeneous photocatalysis is an interesting technology for obtaining several chemicals of industrial use, especially when using TiO2 and g-C3N4 doped with metals, heterojunctions, and macromolecules because these modified catalysts permit higher conversion and selectivity, milder reaction conditions, and reduced cost due to solar light utilization. In order to apply these technologies, it is essential to adopt government policies that promote the use of photocatalysts in the industry, in addition to encouraging active collaboration between photooxidation research groups and companies that process lignocellulosic biomass.

Toward the Photocatalytic Valorization of Lignin: Conversion of a Model Lignin Hexamer with Multiple Functionalities

The valorization of biomass via photocatalysis is an area of expanding research with advances in new technologies and materials with a view toward enhanced sustainability being reported. A significant challenge within this field, however, is understanding the impact photocatalysis has on more recalcitrant compounds present in biomass, such as lignin. Moreover, the current state of lignin model compound research is still largely focused on the breakdown of small models containing typically only one linkage. Described herein is the use of TiO₂-mediated photocatalysis for the degradation of a representative hexameric lignin model compound which contains multiple linkages (e.g., 5-5', β-5, and β-O-4). The results revealed that while cleavage of the β-5 and β-O-4 occurred, the 5-5' appeared to remain intact within the identified reaction intermediates. To understand some of the more fundamental questions, a dimeric compound with a biphenyl linkage was synthesized and studied under photocatalytic conditions. The proposal of intermediates and pathways of degradation based on the studies conducted is presented and discussed herein.

A unified view on catalytic conversion of biomass and waste plastics

Originating from the desire to improve sustainability, producing fuels and chemicals from the conversion of biomass and waste plastic has become an important research topic in the twenty-first century. Although biomass is natural and plastic synthetic, the chemical nature of the two are not as distinct as they first appear. They share substantial structural similarities in terms of their polymeric nature and the types of bonds linking their monomeric units, resulting in close relationships between the two materials and their conversions. Previously, their transformations were mostly studied and reviewed separately in the literature. Here, we summarize the catalytic conversion of biomass and waste plastics, with a focus on bond activation chemistry and catalyst design. By tracking the historical and more recent developments, it becomes clear that biomass and plastic have not only evolved their unique conversion pathways but have also started to cross paths with each other, with each influencing the landscape of the other. As a result, this Review on the catalytic conversion of biomass and waste plastic in a unified angle offers improved insights into existing technologies, and more importantly, may enable new opportunities for future advances.

Biomass and plastic share structural similarities in their composition and types of bond linkage between their monomeric units. Reviewing their catalytic conversion technologies in a unified angle provides new insights and opportunities for future advances.

Recent Advances in Reductive Upgrading of 5-Hydroxymethylfurfural via Heterogeneous Thermocatalysis

The catalytic conversion of 5-hydroxymethylfufural (HMF), one of the vital platform chemicals in biomass upgrading, holds great promise for producing highly valuable chemicals through sustainable routes, thereby alleviating the dependence on fossil feedstocks and reducing CO₂ emissions. The reductive upgrading (hydrogenation, hydrogenolysis, ring-opening, ring-rearrangement, amination, etc.) of HMF has exhibited great potential to produce monomers, liquid fuel additives, and other valuable chemicals. Thermocatalytic conversion has a significant advantage over photocatalysis and electrocatalysis in productivity. In this Review, the recent achievements of thermo-reductive transformation of HMF to various chemicals using heterogeneous catalytic systems are presented, including the catalytic systems (catalyst and solvent), reaction conditions, (reaction temperature, pressure, etc.), and reaction mechanisms. The current challenges and future opportunities are discussed as well, aiming at guiding the catalyst design and practical scalable productions.

Electro- and Photocatalytic Oxidative Upgrading of Bio-based 5-Hydroxymethylfurfural

Conversion of biomass into biofuels and high value-added chemicals is a promising strategy to solve the increasingly deteriorating environmental problems caused by fossil energy consumption. The development of efficient technologies and methods is the premise and guarantee to realize the high-value conversion of biomass. 5-Hydroxymethylfurfural (HMF), as a versatile biomass platform compound, is generated via dehydration of hexoses (e. g., fructose and glucose) derived from cellulosic biomass. This Review gives an overview of the advances and challenges of electro- and photocatalytic oxidation of biomass-derived HMF to high-value chemicals such as 2,5-formylfuran (DFF) and 2,5-furandicarboxylic acid (FDCA). These strategies and methods for the preparation of high-value chemicals by electro- and photocatalytic oxidation of HMF, coupled with, for example, hydrogen evolution reaction, organic substrate reduction, CO₂ reduction reaction, or N₂ reduction reaction, were summarized and discussed. Moreover, the catalytic efficiency and mechanism of different types of catalysts were also introduced in these conversion systems.

Decoupled temperature and pressure hydrothermal synthesis of carbon sub-micron spheres from cellulose

The temperature and pressure of the hydrothermal process occurring in a batch reactor are typically coupled. Herein, we develop a decoupled temperature and pressure hydrothermal system that can heat the cellulose at a constant pressure, thus lowering the degradation temperature of cellulose significantly and enabling the fast production of carbon sub-micron spheres. Carbon sub-micron spheres can be produced without any isothermal time, much faster compared to the conventional hydrothermal process. High-pressure water can help to cleave the hydrogen bonds in cellulose and facilitate dehydration reactions, thus promoting cellulose carbonization at low temperatures. A life cycle assessment based on a conceptual biorefinery design reveals that this technology leads to a substantial reduction in carbon emissions when hydrochar replacing fuel or used for soil amendment. Overall, the decoupled temperature and pressure hydrothermal treatment in this study provides a promising method to produce sustainable carbon materials from cellulose with a carbon-negative effect.

Progress in Catalytic Conversion of Renewable Chitin Biomass to Furan-Derived Platform Compounds

Chitin is one of the most abundant biopolymers on Earth but under-utilized. The effective conversion of chitin biomass to useful chemicals is a promising strategy to make full use of chitin. Among chitin-derived compounds, some furan derivatives, typically 5-hydroxymethylfurfural and 3-acetamido-5-acetylfuran, have shown great potential as platform compounds in future industries. In this review, different catalytic systems for the synthesis of nitrogen-free 5-hydroxymethylfurfural and nitrogen-containing 3-acetamido-5-acetylfuran from chitin or its derivatives are summarized comparatively. Some efficient technologies for enhancing chitin biomass conversion have been introduced. Last but not least, future challenges are discussed to enable the production of valuable compounds from chitin biomass via greener processes.

Cellulose-Derived Carbon Dot-Guided Growth of ZnIn2 S4 Nanosheets for Photocatalytic Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran

Cellulose-derived carbon (CC) dot-directed growth of ZnIn₂ S₄ was achieved through hydrothermal treatment of carboxylated cellulose followed by in situ growth of ZnIn₂ S₄ nanosheets. The carbon dots inherited from carboxylated cellulose equip plenty of surface carboxyl groups, which induce the ionic interaction with Zn²⁺ and In³⁺ and the guided growth of ZnIn₂ S₄ . As a result, the nanosheets of ZnIn₂ S₄ are evenly and intimately grown on the small carbon dots, providing high-speed channels for charges transfer. In conjunction with the reinforced visible-light capture and good conductivity of carbon dots, the resultant CC/ZnIn₂ S₄ shows an outstanding photocatalytic activity. As a proof-of-concept, visible-light-driven 5-hydroxymethylfurfural oxidation into 2,5-diformylfuran was conducted. The evolution of 2,5-diformylfuran over the optimal CC/ZnIn₂ S₄ sample can reach ∼2980 μmol g^-1 , about 3.4 times that of pristine ZnIn₂ S₄ . Additionally, the apparent quantum yield could attain 3.4 % at a wavelength of 400 nm.

Fabrication of Brønsted acidic ionic liquids functionalized organosilica nanospheres for microwave-assisted fructose valorization

A series of Brønsted acidic ionic liquids (BAILs) functionalized hollow organosilica nanospheres ([C_3/4Im][OTs/OTf]-Si(Et)Si, C_3/4 = Pr/BuSO₃H) were synthesized by two steps. The process involved the preparation of hollow nanosphere supports via a toluene-swollen sol-gel co-condensation of 1,2-bis(trimethoxysilyl)ethane and 3-chloropropyltriethoxysilane in the presence of F127, and followed by a successive quaternary ammonization and protonation with imidazole, 1,3-propane/1,4-butane sultone and trifluoromethane sulfonic acid/p-toluenesulfonic acid. The adjustable acid property, hollow inner diameter (5-15 nm) and shell thickness (5-9 nm) of [C_3/4Im][OTs/OTf]-Si(Et)Si are achieved by introducing different organic acids and controlling toluene concentration, respectively. The [C_3/4Im][OTs/OTf]-Si(Et)Si were applied in selective conversion of fructose to 5-hydroxymethylfurfural (HMF) and 5-ethoxymethylfurfural (EMF) under microwave heating. Under the optimized conditions, the [C₄Im][OTs]-Si(Et)Si3.0 nanospheres with the largest inner diameter and the smallest shell thickness exhibit the highest HMF yield (79.4%, 15 min) in fructose dehydration. And the [C₃Im][OTf]-Si(Et)Si0.5 nanospheres with the highest acid strength possess the highest EMF yield (70.4%, 30 min) in fructose ethanolysis. The high Brønsted acid-site density and acid strength of [C_3/4Im][OTs/OTf]-Si(Et)Si catalysts accompanied by high microwave heating energy lead to excellent dehydration/ethanolysis activity. The product selectivity strongly depended on the BAILs structures and morphological characteristics of the catalyst. More importantly, the [C_3/4Im][OTs/OTf]-Si(Et)Si can be reused three times without changes in leaching of BAILs, due to strong covalent bond between BAILs and silicon/carbon framework. This work will provide a simple strategy of chemically bonded BAILs on suitable supports as efficient solid acids, and an approach of combining morphology-controlled solid acids with microwave-heating for catalytic conversion of biomass/derivatives to fuels and value-added chemicals.

Amberlyst-15 supported zirconium sulfonate as an efficient catalyst for Meerwein-Ponndorf-Verley reductions

The Meerwein-Ponndorf-Verley (MPV) reaction is an important chemoselective route for carbonyl group hydrogenation, and thus designing new and effective catalysts for this transformation remains important and challenging. In this work, a new sulfonate coordinated Zr(IV) catalyst was prepared by the coordination of Zr(IV) onto the sulfonate groups of Amberlyst-15, which can effectively catalyze the MPV reaction and quantitatively convert carbonyl compounds to the corresponding alcohols with high reactivity and stability. Detailed mechanistic investigations reveal that the catalytic performance of Zr-AIER can be attributed to the synergetic effect between Zr⁴⁺ and the sulfonate group, and the porous structure with high surface area.

Advancing Strategies of Biofouling Control in Water-Treated Polymeric Membranes

Polymeric membranes, such as polyamide thin film composite membranes, have gained increasing popularity in wastewater treatment, seawater desalination, as well as the purification and concentration of chemicals for their high salt-rejection and water flux properties. Membrane biofouling originates from the attachment or deposition of organic macromolecules/microorganisms and leads to an increased operating pressure and shortened service life and has greatly limited the application of polymeric membranes. Over the past few years, numerous strategies and materials were developed with the aim to control membrane biofouling. In this review, the formation process, influence factors, and consequences of membrane biofouling are systematically summarized. Additionally, the specific strategies for mitigating membrane biofouling including anchoring of hydrophilic monomers, the incorporation of inorganic antimicrobial nanoparticles, coating/grafting of cationic bactericidal polymers, and the design of multifunctional material integrated multiple anti-biofouling mechanisms, are highlighted. Finally, perspectives on the challenges and opportunities in anti-biofouling polymeric membranes are shared, shedding light on the development of even better anti-biofouling materials in near future.