Preparation of furfural and reaction kinetics of xylose dehydration to furfural in high-temperature water

Factors influencing dehydration of xylose to furfural,such as catalyst and extract agents,were investigated.Results indicated that high-temperature water may substitute for solid and liquid acid as a catalyst,and ethyl butyrate improved furfural yield for the high distribution coefficient.A furfural yield of 75 % was obtained at200 °C for 3 h in ethyl butyrate/water.The reaction kinetics of xylose dehydration to furfural was investigated and it was found that the reaction order was 0.5,and the activation energy was 68.5 k J/mol.The rate constant k showed a clear agreement with the Arrhenius law from160 to 200 °C.

Establishment and verification of a model for the movement of pulverized sweet sorghum stalks in a rotary drum bioreactor by discrete element method

The mixing of raw materials in a rotary drum bioreactor is important for advanced solid-state fermentation technology.However,the shape,size,and other properties of pulverized sweet sorghum stalk particles are more complicated than those of the spherical particles.In this study,a soft rod-shaped discrete particle model was established and verified to simulate the mixing behavior of sweet sorghum stalk particles in a rotary drum bioreactor.We were inspired by the particle shape and established a rod-shaped particle model by investigating the influence of the shape(length-diameter ratio)and size(diameter)on the particle packing(stack height and bed porosity).We used orthogonal simulations and extremum difference analysis to determine the main factors,optimum level,and groups of other parameters.Based on calibrated parameters,twelve sets of simulations of radial mixing in the drum were performed,and the results were compared with experiments conducted under identical operating conditions.The average relative error between the simulation and the experiment was 10.95%,which indicates that they agreed well and that the simulation could predict the mixing process well.

Catalytic hydrothermal liquefaction of microalgae over metal incorporated mesoporous SBA-15 with high hydrothermal stability

Hydrothermal liquefaction(HTL)is one of the most promising technologies for conversion of microalgae,and catalysts with high hydrothermal stability are required for controllable HTL.In this article,SBA-15 incorporated with transition metals(Ni,Pd,Co and Ru)were synthetized via double-template method for catalytic HTL of microalgae.The results showed that metal incorporated SBA-15 represented high hydrothermal stability at 613 K.The incorporated Ni,Co and Ru was dispersed in SBA-15 enhancing the hydrothermal stability.The catalysts greatly influenced the chemical composition of the obtained bio-oil,which contained a higher percentage of furfural derivatives and a lower content of fatty acids and N-containing compounds,thus bio-oil quality was improved significantly.Higher hydrothermal stability and specific surface areas of Co-SBA-15 contribute to the highest preformation with 78.78%conversion and 24.11 wt%bio-oil yield.Metal incorporated SBA-15 provides a potential application for biomass conversion in high-temperature aqueous phase.

Development of a whole-cell biosensor based on an ArsR-Pars regulatory circuit from Geobacter sulfurreducens

In this study,an Escherichia coli(E.coli)whole-cell biosensor for the specific detection of bioavailable arsenic was developed by placing a green fluorescent protein(GFP)reporter gene under the control of the ArsR1(GSU2952)regulatory circuit from Geobacter sulfurreducens.E.coli cells only emitted green fluorescence in the presence of arsenite and were more sensitive to arsenite when they were grown in M9 supplemented medium compared to LB medium.Under optimal test conditions,the Geobacter arsR1 promoter had a detection limit of 0.01 mM arsenite and the GFP expression was linear within a range of 0.03-0.1 mM(2.25-7.5 mg/l).These values were well below World Health Organization’s drinking water quality standard,which is 10 mg/l.The feasibility of using this whole-cell biosensor to detect arsenic in water samples,such as arsenic polluted tap water and landfill leachate was verified.The biosensor was determined to be just as sensitive as atomic fluorescence spectrometry.This study examines the potential applications of biosensors constructed with Geobacter ArsR-Pars regulatory circuits and provides a rapid and cost-effective tool that can be used for arsenic detection in water samples.