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Abstract Pretreatment is an important upstream process that affects the economics of biofuels production from lignocellulose. Hydrotropic reagent sodium xylene sulfonate (SXS) was used in this study to treat wheat straw for efficient butanol production. Effects of temperature, time, SXS concentration on pretreatment were evaluated. In addition, a modified SXS pretreatment method with pH adjusted to 3.5 by formic acid was also conducted for efficient wheat straw conversion by removing hemicellulose fraction. Composition analysis, structure characterization, enzymatic hydrolysis and fermentation tests were conducted. The results showed that modified SXS pretreatment can be considered as an efficient method for improving wheat straw conversion efficiency for ABE production. The hexoses and pentoses in the enzymatic hydrolysates can be used by C. acetobutylicum for butanol production with 12.41 g L−1 ABE produced, and the overall ABE yield of 100 g ABE/kg wheat straw was obtained. This study revealed that hydrotropic pretreatment provides an alternative potential to the conventional pretreatment processes for butanol production. Graphical abstract Image 1 Highlights • Wheat straw was pretreated by hydrotrope under different conditions. • Hydrotrope pretreatment could remove lignin from wheat straw effectively. • Hemicellulose can be removed by modified hydrotrope pretreatment. • Modified hydrotrope pretreatment enhanced polysaccharides digestibility. • Hydrotrope pretreatment provides potential for butanol production from wheat straw. [ABSTRACT FROM AUTHOR]

Extraction of high-value products from agricultural wastes is an important component for sustainable bioeconomy development. In this study, wax extraction from sugarcane bagasse was performed and the beneficial effect of dewaxing pretreatment on the enzymatic hydrolysis was investigated. About 1.2% (w/w) of crude sugarcane wax was obtained from the sugarcane bagasse using the mixture of petroleum ether and ethanol (mass ratio of 1:1) as the extraction agent. Results of Fourier-transform infrared characterization and gas chromatography–mass spectrometry qualitative analysis showed that the crude sugarcane wax consisted of fatty fractions (fatty acids, fatty aldehydes, hydrocarbons, and esters) and small amount of lignin derivatives. In addition, the effect of dewaxing pretreatment on the enzymatic hydrolysis of sugarcane bagasse was also investigated. The digestibilities of cellulose and xylan in dewaxed sugarcane bagasse were 18.7 and 10.3%, respectively, compared with those of 13.1 and 8.9% obtained from native sugarcane bagasse. The dewaxed sugarcane bagasse became more accessible to enzyme due to the disruption of the outermost layer of the waxy materials. [ABSTRACT FROM PUBLISHER]

A heterojunction structure LaVO4/g-C3N4 composite with oxygen defects was successfully prepared. The characterization results show that the recombination of electron–hole pairs could be inhibited by the heterojunction structure. The LaVO4/g-C3N4 composite shows superior photocatalytic water splitting performance for the generation of hydrogen and oxygen under visible light irradiation. Experimental data show that under visible light irradiation, the hydrogen and oxygen evolution rates of the LVOCN1 composite are much higher than those of fresh carbon nitride. Moreover, the photocatalytic activity of LaVO4/g-C3N4 composites could be significantly enhanced by O defects. Mechanism studies display that the possible mechanism of the photocatalytic water splitting reaction is the Z scheme mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Growing concern about sulfur dioxide (SO2) emission from diesel exhaust causing a serious threat to the environment and human health necessitated enhanced desulfurization materials for dry desulfurization filters. MnO2 was modified with various alkali metal ions by impregnation to strengthen its SO2 capture capacity. The prepared materials were characterized by various technologies. Their SO2 capture capacities were measured by thermogravimetry, and the sulfate reaction mechanism was also evaluated. The results confirm that the SO2 capture performance of MnO2 could be significantly enhanced by doping with alkali metals. The prepared Li‐doped MnO2 has good SO2 trap capacity with improved absorbance being 64 % higher than that of MnO2. The grain model can be applied to explain the sulfate reaction mechanism between Li‐doped MnO2 and SO2. The activation energy was calculated by the grain model equations. [ABSTRACT FROM AUTHOR]

The recovery of levulinic acid (LA) from aqueous solution and actual biomass hydrolysate by a microporous hyper-cross-linked polymer, SY-01, was investigated for the first time under batch and fixed-bed column conditions. The results showed that the optimum pH should be in the acidic range (pH < 3.0) without adjusting the pH. In the single-component system equilibrium study, the Langmuir isotherm model fits the LA adsorption onto SY-01 resin better than the Freundlich isotherm model, indicating that LA adsorption onto SY-01 resin under the concentration range studied is a monolayer homogeneous adsorption process. The maximum adsorption capacity of LA onto SY-01 resin decreased with increasing temperature, ranging from 103.74 to 95.70 mg/g. The obtained thermodynamic parameters suggested that the adsorption of LA on SY-01 was spontaneous ( ΔG 0 <−3.788 kJ/mol), and exothermic ( ΔH 0 = −11.764 kJ/mol). For kinetic study, the adsorption of LA onto SY-01 resin at various operating conditions follows the pore diffusion model and the intraparticle diffusion is the rate-limiting step for the adsorption of LA onto SY-01 resin. The effective pore diffusivity was dependent upon temperature, but independent of initial LA concentration, and were 3.306 × 10 −10 , 5.274 × 10 −10 and 7.707 × 10 −10 m 2 /s at 298, 318 and 338 K, respectively. In desorption process, the recovery efficiency of LA from SY-01 resin was 99.39%, and LA concentration in the eluent was raised 2.97-fold. In conclusion, our results show that the SY-01 resin has potential application in product recovery of LA from biomass hydrolysate. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA) adsorption on a microporous hyper-cross-linked adsorption resin, SY-01, from aqueous solution was performed in a fixed-bed column. Batch equilibrium isotherm was analyzed using Langmuir and Freundlich isotherm models, and the Langmuir isotherm model was found to fit the adsorption isotherm data well. The effects of feed flow rate ( Q f = 1.0–5.0 mL/min), initial LA concentration ( c f = 1.0–10.0 g/L), fixed-bed column length ( L c = 5.65–16.96 cm) and fixed-bed column diameter ( D c = 1.6–5.5 cm) on the adsorption characteristics of LA were investigated systematically. The results show that an increase in fixed-bed column length, fixed-bed column diameter, initial LA concentration and a decrease in feed flow rate improve the adsorption performance. Furthermore, a general rate model (GRM) was developed for predicting adsorption breakthrough curves of LA. The mathematical model results were in good agreement with the experimental data under various operating conditions, which confirmed that the GRM can successfully simulate this process. In addition, the values of Biot number ( Bi ) at different operating conditions were all more than 10, demonstrating intraparticle diffusion is the rate controlling step for the adsorption of LA on the resin. In conclusion, our results provide an important basis for future scale-up of the product recovery of LA from biomass hydrolysate. [ABSTRACT FROM AUTHOR]

• The Pd facet-dependent EHDC activity was revealed under different potentials. • The rate-determining step of EHDC evolved with the potential moving negatively. • The active site density for H* generation and the d band center are two key features. • The Pd (1 1 0) with a large density of active sites facilitated the H* generation. • The Pd (1 1 1) with a low d band center facilitated the phenol desorption. Clarifying the reaction mechanism of electrocatalytic hydrodechlorination (EHDC) and identifying the catalytically favorable surface structure on Pd were crucial to maximize its power in remediating the chlorinated phenol pollutants. Herein, a study of the Pd facet-dependent EHDC performance toward 2,4-dichlorophenol (2,4-DCP) revealed the EHDC efficiency was governed by the H* yield on Pd at the potential above −0.80 V vs. Ag/AgCl, the phenol desorption at −0.80~−0.90 V and the intensity of the electrostatic field-induced repulsive force between 2,4-DCP and the cathode at the potential beyond −0.95 V. Further rationalization of the facet effect with the surface electronic/geometric structure of Pd demonstrated the density of active sites for H* generation and the d band center were two key structural properties. The Pd (1 1 0) with large density of active sites and the Pd (1 1 1) with a low d band center were the ideal facet to facilitate H* generation and phenol desorption, respectively. [ABSTRACT FROM AUTHOR]

Understanding the interaction mechanisms between xylan and xylan-degrading enzymes is beneficial to the efficient hydrolysis of xylan. Xylan from sugarcane bagasse (SB) was extracted and characterized. The effects of heat treatment and removal of side chains of SB xylan on the hydrolytic efficiency and synergistic action of endo-β-1,4-xylanases (HoXyn11A and AnXyn10C), β-xylosidases (AnXln3D), and α- l -arabinofuranosidases (AnAxh62A) were investigated. Results indicated that heat treatment of xylan can improve the hydrolytic efficiency of xylan-degrading enzymes, and it is essential for the efficient hydrolysis of xylan by HoXyn11A. The removal of arabinofuranosyl side chains of xylan by AnAxh62A before enzymatic hydrolysis reduced the hydrolytic efficiency of HoXyn11A and AnXyn10C on xylan. AnXyn10C was more efficient than HoXyn11A in hydrolysis of xylan, whereas HoXyn11A showed better synergistic action than AnXyn10C with AnAxh62A and AnXln3D in the hydrolysis of xylan. This study provides new insights on the enzymatic hydrolysis of SB into monosaccharides and xylo-oligosaccharides. [ABSTRACT FROM AUTHOR]

This study aims to propose a biorefinery pretreatment technology for the bioconversion of sugarcane bagasse (SB) into biofuels and N-fertilizers. Performance of diluted acid (DA), aqueous ammonia (AA), oxidate ammonolysis (OA) and the combined DA with AA or OA were compared in SB pretreatment by enzymatic hydrolysis, structural characterization and acetone-butanol-ethanol (ABE) fermentation. Results indicated that DA-OA pretreatment improves the digestibility of SB by sufficiently hydrolyzing hemicellulose into fermentable monosaccharides and oxidating lignin into soluble N-fertilizer with high nitrogen content (11.25%) and low C/N ratio (3.39). The enzymatic hydrolysates from DA-OA pretreated SB mainly composed of glucose was more suitable for the production of ABE solvents than the enzymatic hydrolysates from OA pretreated SB containing high ratio of xylose. The fermentation of enzymatic hydrolysates from DA-OA pretreated SB produced 12.12 g/L ABE in 120 h. These results suggested that SB could be utilized efficient, economic, and environmental by DA-OA pretreatment. [ABSTRACT FROM AUTHOR]

In this study, fly ash and hydrogen peroxide (H 2 O 2) assisted hydrothermal carbonization (HTC) was used to improve the removal efficiency of nitrogen (N) and sulfur (S) from sewage sludge (SS). The removal rate and distribution of N and S in hydrochar were evaluated, and properties of the aqueous phase were analyzed to illustrate the N and S transformation mechanism during fly ash and H 2 O 2 assisted HTC treatment of SS. The results suggested that during HTC process assisted by fly ash (10% of raw SS), dehydration, decarboxylation and hydrolysis of SS were strengthened due to the catalysis effect. The N and S removal were promoted marginally. For hydrochar achieved from HTC process with H 2 O 2 addition, the N and S removal were improved slightly due to the biopolymer oxidization by ‧OH released from H 2 O 2 decomposition. While for HTC treatment with fly ash and H 2 O 2 supplementation, a positive synergistic effect on N and S removal was observed. The N and S removal obtained from fly ash (10% of raw SS) and H 2 O 2 (48 g/L) assisted HTC increased to 81.71% and 62.83%, respectively, from those of 69.53% and 49.92% in control group. N and S removal mechanism analysis suggested that hydroxyl radicals (‧OH) produced by H 2 O 2 decomposition will destroy SS structure, and the biopolymers such as polysaccharides and proteins will be decomposed to release N and S into the liquid residue. In addition, the fly ash acts as the catalyst will decrease the energy need for denification and desulfartion. Consequently, N and S removal efficiency was enhanced by fly ash and H 2 O 2 assisted HTC treatment. [Display omitted] • Fly ash and H 2 O 2 assisted HTC was used to remove N/S from sewage sludge. • C, N and S yield and distribution in hydrochar was investigated. • N and S removal increased by 36.02% and 25.40% by fly ash and H 2 O 2 assisted HTC. • Fly ash and H 2 O 2 assisted HTC facilitated N/S removal from sewage sludge. • Catalysis and oxidization effect contributed to the low N/S contents in hydrochar. [ABSTRACT FROM AUTHOR]