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The selective photocatalytic C–C bond cleavage of biomass coupling with H–O bond cleavage of water for co-producing chemicals and H2 is of great significance, but limited successes have been reported. In this study, a RuS2@CN-x photocatalyst with only exposed crystal face (200) was prepared by anchoring RuS2 nanoparticles on carbon nitride (CN) nanosheets and successfully used in photocatalytic C–C bond cleavage of biomass-based sugars coupling with water splitting to co-generate lactic acid and hydrogen. Interestingly, the RuS2 (200) crystal face combined with the interfacial synergism between CN and RuS2 in RuS2@CN-x effectively improved visible light absorption and enhanced the transfer/separation efficiency of photo-generated carriers. The RuS2@CN-2 exhibited superior photocatalytic activity towards synchronous water splitting and biomass conversion to co-produce hydrogen (8698.3 μmol g−1 h−1) and lactic acid (91.5%). Furthermore, the experimental and DFT calculation results indicated that the exposed crystal face (200) of RuS2 significantly enhanced the photocatalytic activity of RuS2@CN-2. Moreover, this reaction system not only has excellent recyclability but also displays excellent universality for small molecule biomass-derived monosaccharides and macromolecular xylan. This work provides a novel route to efficiently co-produce hydrogen and fine chemicals from photocatalytic C–C bond cleavage of biomass coupling with H–O bond cleavage of water. [ABSTRACT FROM AUTHOR]

Residual lignin plays an inhibitory role in the enzymatic hydrolysis of cellulosic biomass. In this study, we examined the structural changes in isolated lignins from the hot water hydrothermal pretreatment of aspen and their inhibitory effects on the enzymatic hydrolysis of Avicel. The functional groups of the isolated lignins were determined using quantitative 13C, 2D HSQC and 31P NMR. The increase in pretreatment severity significantly increased the condensed and non-condensed syringyl and guaiacyl OH group content in the isolated lignins, but decreased the aliphatic OH, p-hydroxybenzoate OH and carboxylic OH group content. A compelling adverse association (r2 = 0.998) was observed between the condensed syringyl and guaiacyl phenolic OH group content in lignins and their inhibitory effects on enzymatic hydrolysis. Langmuir adsorption isotherms showed that a higher pretreatment severity resulted in a higher binding ability between the isolated lignins and the cellulase enzymes, which led to more non-productive binding. It is hypothesized that condensed syringyl and guaiacyl phenolic units are mainly responsible for the inhibitory effect of lignin on enzymatic hydrolysis, in which the condensed aromatic rings enhance the hydrophobic interactions and the phenolic OH group boosts the hydrogen bonding. The combination of hydrophobic interactions and hydrogen bonding can further intensify undesirable non-productive binding. [ABSTRACT FROM AUTHOR]

Photocatalytic biorefinery integrated with CO 2 reduction to co-produce value-added chemicals and fuels is significant but challenging. Herein, a novel photocatalyst with dual active sites is constructed, in which Ru single atoms coordinated with N 2 O 2 on phosphorus-doped carbon nitride (Ru 1 N 2 O 2 @PCN x) via a pre-assembled pyrolysis strategy. Ru 1 N 2 O 2 @PCN 1.0 catalyst exhibits an exceptional performance in both CO 2 reduction and biorefinery processes, originating from the high photon-to-electron conversion rate. It achieves an extraordinary CO 2 reduction and biorefinery, with 100.1 μmol g−1 h−1 evolution of CO and 91.2% yield of lactic acid. Furthermore, the as-prepared Ru 1 N 2 O 2 @PCN 1.0 is successfully used in biomass-derived monosaccharides and xylan systems, validating the universality for broad applications. Experimental and theoretical analysis indicates that doping P in CN by replacing a corner C atom facilitates charge transfer/separation. Additionally, the introduction of Ru-N 2 O 2 coordination regulates the electronic structure of CN and reduces the reaction energy barrier. [Display omitted] • The dual active moieties of Ru-N 2 O 2 and P-N on CN nanosheets were designed. • Photocatalytic CO 2 reduction and biorefinery were achieved simultaneously. • CO evolution rate over Ru 1 N 2 O 2 @PCN x is 2.02 times higher than pure CN. • A high lactic acid yield of 91.2% was obtained over Ru 1 N 2 O 2 @PCN x. [ABSTRACT FROM AUTHOR]

Selective oxidation of biomass-based monosaccharides into value-added sugar acids is highly desired, but limited success of producing d-xylonic acid has been achieved. Herein, we report an efficient catalyst system, viz., Au nanoparticles anchored on the inner walls of hollow Al2O3 nanospheres (Au@h-Al2O3), which could catalyze the selective oxidation of d-xylose into d-xylonic acid under base-free conditions. The mesoporous Al2O3 shell as the adsorbent first adsorbed d-xylose. Then, the interface of Au nanoparticles and Al2O3 as active sites spontaneously dissociated O2, and the exposed Au nanoparticle surface as the catalytic site drove the transformation. With this catalyst system, the valuable d-xylonic acid was produced with excellent yields in the aerobic oxidation of d-xylose. Extensive investigation showed that Au@h-Al2O3 is an efficient catalyst with high stability and recyclability. [ABSTRACT FROM AUTHOR]

Compressive, ultralight and fire-resistant graphene aerogel is facilely modified by renewable lignin biomass with hydrophobic and porous skeletons. The lignin-modified graphene aerogel (LGA) show highly efficient absorption of not only petroleum oils, but also toxic solvents such as toluene, chloroform and carbon tetrachloride (up to 350 times of its own weight), which is superior to that of graphene aerogel (GA) and among the highest in previous reported absorbents. Even after several compressive and release cycles, their absorption capacity are also maintained at 96%. Moreover, the absorption capacity can be further improved by carbonation treatment maximum up to 522 times of its own weight. Importantly, the LGA can be regenerated by repeated heat treatment and squeezing method, yielding almost full release of adsorbates. Such a high efficient, recyclable and renewable LGA exhibits it a potential candidate for applications in oil-water separation and also paves way to high-valued utilization of biomass waste. [ABSTRACT FROM AUTHOR]

Lignin is the renewable source of aromatics in nature, and the conversion of lignin into vanillin is very attractive. However, the vanillin yield is closely related to the resource of lignin and its isolation process, and relatively low yield of vanillin is always obtained from lignin. In order to improve the vanillin yield from lignin, in this work, the relationship between lignin linkages and vanillin yield was explored. Five lignins (kraft lignin, alkali lignin, lignosulfonate, and two enzymatic lignins) and various lignin model compounds (monomers, dimers, and polymers) were characterized by NMR spectroscopy and oxidized to prepare vanillin. Results indicated that the interunit linkages of the lignin had a significant influence on the vanillin yield. The more β- O -4 linkages in lignin, the higher yield of corresponding aldehydes was obtained. It is believed that the vanillin yield can be significantly improved by using lignins with high content of β- O -4 linkages. [ABSTRACT FROM AUTHOR]

Fabrication of cost-effective and eco-friendly hierarchical porous carbons from the most abundant and widely available biomass cellulose represents a critical and sustainable way to solve the crisis of fossil resources. In this work, a hierarchical porous carbon aerogel with desirable macropores, mesopores, and micropores was obtained via dissolving-gelling and subsequent carbonizing-activating process. The CO 2 activated carbon aerogel had a high specific surface area of 1364 m 2 /g and a high specific capacitance of 328 F g −1 (0.5 A g −1 , 1.0 M H 2 SO 4 ) as well as an outstanding cycling stability with 96% of the capacitance retention after 5000 charge/discharge cycles. More importantly, for the first time, we demonstrated that the cellulose-derived hierarchical porous carbon aerogel showed a good CO 2 adsorption capacity of 3.42 mmol/g (at 1 atm and 298 K), which indicates the possibility of using this carbon aerogel for CO 2 capture. [ABSTRACT FROM AUTHOR]

• The FG- s -PVA@CNNS has fast charge separation rate and low resistance. • The FG- s -PVA@CNNS shows excellent performance for lactic acid synthesis. • The ·O 2 - played a primary role for lactic acid synthesis. • Good yield of lactic acid was observed from 1000-fold scale-up experiment. The development of hydrogel-based photocatalysts with three-dimensional ordered porous structure, fast charge separation, and low resistance is significantly in photocatalytic biorefinery but nonetheless poses certain challenges. Herein, we introduced a novel strategy to prepare "Fish gill"-shaped hydrogel-based photocatalysts via freezing-induced encapsulation of ultra-thin carbon nitride nanosheets into a three-dimensional ordered porous polyvinyl alcohol matrix (name as FG- s -PVA@CNNS x). The encapsulation of CNNS in FG- s -PVA@CNNS 3 posed no effects on the absorption of visible light but accelerated the transfer/migration of photo-induced charge and reduced the resistance. For photocatalysis, the ordered porous structure of FG- s -PVA@CNNS 3 proved to be conducive to the reactants adsorption and mass transfer while the lactic acid yield achieved 92.6%. FG- s -PVA@CNNS 3 exhibited excellent stability and reusability, in which the yield of the 10th cycle well reached 95.6% of its first cycle. FG- s -PVA@CNNS 3 also displayed exceptional universality wherein the lactic acid yields were 92.6% (glucose), 89.1% (fructose), 88.6% (mannose), 56.0% (rhamnose), 71.1% (arabinose), and 70.9% (xylose). In addition, the effects of various oxidative species on the photocatalytic reaction were systematically discussed, among which ·O 2 - played a pertinent role. Overall, the construct of hydrogel-based photocatalysts and their application provide a strategy for photocatalytic biorefinery. [Display omitted]. [ABSTRACT FROM AUTHOR]

Photocatalysis provides a promising opportunity for selective oxidation of biomass to high-value chemicals under mild conditions. The key to realize this transformation is to design a cost-effective and environmentally friendly photocatalyst. Here, we report the preparation of a carbon nitride photocatalyst with controllable carbon/nitride (C/N) ratio and its application in the selective photocatalytic synthesis of lactic acid from biomass-derived monosaccharides. Reasonable C/N ratio in the catalyst can significantly enhance the visible light absorption range and accelerate the mobility of photogenerated carriers. The obtained photocatalyst exhibited excellent photocatalytic activity, yielding 76.8% lactic acid. All of the h+,·O 2 -,·OH and 1O 2 are beneficial for lactic acid production, and the·O 2 - plays a major role. Furthermore, the photocatalyst exhibited excellent reusability and universality. The 1000-fold scale-up experiments indicated that the system has potential for industrial production of lactic acid. Therefore, the present work offers a promising example for photocatalytic reforming of biomass. Reasonable regulation of carbon/nitride ratio in carbon nitride for efficient photocatalytic reforming of biomass-derived feedstocks to lactic acid [Display omitted] • A photocatalyst (CC 1 @mCN 10) with controllable carbon/nitride ratio was prepared. • Reasonable C/N ratio in the catalyst enhance the visible light absorption range. • The·O 2 - plays a major role on the synthesis of lactic acid. • The CC 1 @mCN 10 shows excellent stability and reusability. [ABSTRACT FROM AUTHOR]

Abstract: During the past few decades, much effort has been devoted to increasing the utilization of lignocellulosic biomass to create biofuels, biochemicals, biocomposites, and a host of other bioproducts to replace fossil-based products. Recently, the utilization of lignocellulosic biomass received much more attention in ionic liquids with strong hydrogen-bond-destroying ability to produce lignocellulosic derivatives containing new functionality. In present study, carboxyl groups were attached onto sugarcane bagasse (SCB) by the homogenous modification of SCB with maleic anhydride in ionic liquid 1-butyl-3-methylimidazolium chloride (BMIMCl) without any catalysts. The parameters optimized included maleic anhydride concentration, reaction temperature and reaction time required in the process. The extent of maleation of SCB was measured by the weight percent gain (WPG), which increased with an increment of maleic anhydride concentration between 1:1 and 5:1 (g/g, maleic anhydride/SCB). It should be noted that WPG decreased at wild conditions, including long reaction duration (>60min) and high temperature (>110°C). The results from FT-IR and solid-state CP/MAS 13C NMR spectroscopies indicated that the maleation of hydroxyl groups in lignin, cellulose and hemicelluloses all occurred. XRD, SEM and TGA/DTG analyses of the native and modified SCB showed that the cellulose crystalline structure of SCB was significantly destroyed after dissolution, maleation, and regeneration in IL. However, the remained cellulose crystalline structure did not change except remarkable decrystallization. The thermal stability of the maleated SCB decreased at low temperature (lower than 300°C), and increased at high temperature (above 300°C) compared with that of native ball-milled SCB. [Copyright &y& Elsevier]

Photocatalytic oxidation of xylose to xylonic acid. [Display omitted] • A hydrothermal method has been reported for the one-step controllable synthesis of efficient and stable ZnS@Bi 2 S 3 nanosheets. • ZnS@Bi 2 S 3 nanosheets photocatalytically efficiently convert monosaccharides into sugar acids. • Provides a new strategy for the oxidation of monosaccharides to the industrialization of sugar acids. Herein, a new hydrothermal method has been reported for one-step controllable synthesis of ZnS@Bi 2 S 3 nanosheets, which were used for the highly selective oxidation of biomass-derived monosaccharides to produce value-added sugar acids. The results of the photocatalytic oxidation by ZnS@Bi 2 S 3 were compared with that by pure Bi 2 S 3, under the same reaction conditions. Compared to pure Bi 2 S 3, ZnS@Bi 2 S 3 nanosheets has showed broadened band gap and improved stability. The relative band alignment indicated that the ZnS@Bi 2 S 3 nanosheets could suppress the recombination of photogenerated charge carriers to improve the photocatalytic activity. Density functional theory (DFT) calculations were performed to investigate the photocatalytic reaction mechanism where xylose and oxygen are adsorbed on Bi 2 S 3 (113) and ZnS (111). The xylose adsorbed on the catalytic surfaces reacted with the active free radicals generated from the photocatalytic process, and then was selectively oxidized to xylonic acid. [ABSTRACT FROM AUTHOR]

Driven by the depletion of fossil energy sources and increasing demand for CO 2 emission mitigation, the global production of densified biofuel increased dramatically from less than 7 Mt in 2006 to higher than 26 Mt in 2015. Codensification, which bridges biomass densification with other clean technologies through pellet formulation diversification, is attracting attention from researchers worldwide. This paper provides a comprehensive overview of the current lab-scale research framework, the fuel pellet quality evaluation indexes, the latest characterization methods, and novel sources and functionalities of different materials used in codensification. This paper emphasizes the distinct role of codensification as a bridge between existing and emerging biomass conversion routes, waste treatment processes, and fossil resource refinery technologies, and discussed this technology's potential in energy recovery from different resources, including low-fuel-quality biomass and difficult-to-handle wastes/byproducts such as municipal solid waste, sewage sludge, pyrolysis oil and minerals. This work also identified future research challenges, namely, further understanding the particle interaction/binding mechanism during codensification and its effects on the pellet quality, and comprehensively evaluating the social, economic, and environmental impacts of composite pellets during their lifecycle. Image 1 • Biomass pellet formulation plays a critical role in sustainable energy research. • Codensification bridges the gaps between different clean technologies. • Review of standards, research framework, and characterization methods. • Discussion of sources and functions of secondary feedstock and additives. • Mapping of the linkage between codensification and other technologies. [ABSTRACT FROM AUTHOR]

Low cost fabrication of water treatment polymer materials directly from biomass resources is urgently needed in recent days. Herein, a compressive alginate sponge (AS) is prepared from seaweed biomass resources through a green two-step lyophilization method. This material is much different from conventional oven-, air-, vacuum-dried alginate-based adsorbents, which show limitations of shrinkage, rigidness, tight nonporous structure and restricted ions diffusion, hindering its practical applications, and was used to efficiently remove methylene blue (MB), a main colorful contaminant in dye manufacturing, from wastewater. The batch adsorption studies are carried out to determine the impact of pH, contact time and concentration of dye on the adsorption process. The maximum adsorption capacity can be obtained at 1279 mg g−1, and the shape-moldable AS can be facilely utilized as a fixed-bed absorption column, providing an efficient approach for continuous removal of MB within a short time. It is also important that such a compressive AS can be regenerated by a simple squeezing method while retaining about 70% capacity for more than ten cycles, which is convenient to be reused in practical water treatment. Compressive AS demonstrates its merits of high capability, large efficiency and easy to recycle as well as low cost resources, indicating widespread potentials for application in dye contaminant control regarding environmental protection. [ABSTRACT FROM AUTHOR]

Background: Dilute oxalic acid pretreatment has drawn much attention because it could selectively hydrolyse the hemicellulose fraction during lignocellulose pretreatment. However, there are few studies focusing on the recovery of oxalic acid. Here, we reported a new approach to recycle oxalic acid used in pretreatment via ethanol extraction. Results: The highest xylose content in hydrolysate was 266.70 mg xylose per 1 g corncob (85.0% yield), which was achieved using 150 mmol/L oxalic acid under the optimized treatment condition (140 °C, 2.5 h). These pretreatment conditions were employed to the subsequent pretreatment using recycled oxalic acid. Oxalic acid in the hydrolysate could be recycled according to the following steps: (1) water was removed via evaporation and vacuum drying, (2) ethanol was used to extract oxalic acid in the remaining mixture, and (3) oxalic acid and ethanol were separated by reduced pressure evaporation. The total xylose yields could be stabilized by intermittent adding oxalic acid, and the yields were in range of 46.7–64.3% in this experiment. Conclusions: This sustainable approach of recycling and reuse of oxalic acid has a significant potential application for replacing traditional dilute mineral acid pretreatment of lignocellulose, which could contribute to reduce CO2 emissions and the cost of the pretreatment. [ABSTRACT FROM AUTHOR]