Anion exchange membranes with a semi-interpenetrating polymer network using 1,6-dibromohexane as bifunctional crosslinker

An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of AEMs,semi-interpenetrating polymer networks(SIPNs)have been suggested for their structural superiorities,i.e.,the tunable local density of ion exchange groups for IEC and the restrained leaching of hygroscopic groups by insolubility for WU.Unfortunately,the conventional SIPN AEMs still struggle to balances IEC,WU,and mechanical strength simultaneously,due to the lack of the compact crosslinking region.In this work,we proposed a novel SIPN structure of polyvinylidene difluoride/polyvinylimidazole/1,6-dibromohexane(PVDF/PVIm/DBH).On the one hand,DBH with two cationic groups of imidazole groups are introduced to enhance the ion conductivity,which is different from the conventional monofunctional modifier with only one cationic group.On the other hand,DBH has the ability to bridge with PVIm,where the mechanical strength of the resulting AEM is increased by the increase of crosslinking degree.Results show that a low WU of 38.1%to 62.6%,high IEC of 2.12—2.22 mmol·g^(-1),and excellent tensile strength of 3.54—12.35 MPa for PVDF/PVIm/DBH membrane are achieved.This work opens a new avenue for achieving the high-quality AEMs.

2,5-Diformylfuran production by photocatalytic selective oxidation of 5-hydroxymethylfurfural in water using MoS_(2)/CdIn_(2)S_(4) flower-like heterojunctions

The selective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) is an important reaction for renewable biomass building blocks. Compared with thermal catalytic processes, photocatalytic production of DFF from HMF has attracted tremendous attention. Herein, the MoS_(2)/CdIn_(2)S_(4)(MC)flower-like heterojunctions were prepared and considered as photocatalysts for selective oxidation of HMF into DFF under visible-light irradiation in aqueous solution. Results demonstrated MoS_(2) in MC heterojunction could promote the separation of photoexcited electron-hole pairs, while the amount of MoS_(2) dropping was proved influenced on the photocatalytic performance. 80.93% of DFF selectivity was realized when using 12.5% MC as photocatalyst. In addition, the MC catalyst also showed great potential in transformation of other biomass derived benzyl-and furyl-alcohols. The catalytic mechanism suggested that ·O_(2)^(-) was the decisive active radical for HMF oxidation. Therefore, the MC heterojunction could be applied in photocatalytic conversion of biomass to valuable chemicals under ambient condition.

Facile biphasic catalytic process for conversion of monoterpenoids to tricyclic hydrocarbon biofuels

Terpenoids have drawn much attention to scientists in synthesizing high-performance bio-jet fuels due to their ring structures,which feature potential high densities.Here,a facile biphasic catalytic process has been developed for the production of high-density tricyclic hydrocarbon biofuels from a monoterpenoid,1,8-cineole,using sulfuric acid(H2SO4)as the homogeneous catalyst.A^100%conversion of 1,8-cineole and a>40%carbon yield of cyclic dimers were achieved at 100℃within two hours.The mechanism for the acid-catalyzed conversion of 1,8-cineole to cyclic hydrocarbon dimers were explored.In particular,the formation of the diene intermediates and the following dimerization of dienes was essential to synthesize tricyclic terpene dimers.The biphasic catalytic process accelerated the deoxygenation rate and enabled the dimerization with the aid of organic solvent while controlling the reaction rates to avoid the formation of solid residues.Moreover,this process also facilitated the product separation by organic solvent extraction while enabling easy recycle of the homogenous catalysts.

Ultrathin polyamide nanofiltration membrane prepared by triazine-based porous organic polymer as interlayer for dye removal

Separation membrane with high flux is generally encouraged in industrial application,because of the tremendous needs for decreasing membrane areas,usage costs and space requirements.The most effective and direct method for obtaining the high flux is to decrease membrane thickness.Polyamide(PA)nanofiltration membrane is conventionally prepared by the direct interfacial polymerization(IP)on substrate surface,and results in a thick PA layer.In this work,we proposed a strategy that constructing triazine-based porous organic polymer(TRZ-POP)as the interlayer to prepare the ultrathin PA nanofiltration membranes.TRZ-POP is firstly deposited on the polyethersulfone substrate,and then the formed TRZ-POP provides more adhesion sites towards PA based on its high specific surface areas.The chemical bonding between terminal amine group of TRZ-POP and the amide group of PA further improves the binding force,and strengthens the stability of PA layer.More importantly,the high porosity of TRZPOP layer causes the higher polymerization of initial PA owning to the stored sufficient amino monomer;and H-bonding interaction between amine groups of TRZ-POP and piperazine(PIP)can astrict the release of PIP.Thus,IP process is controlled,and the thinnest thickness of prepared PA layer is only<15 nm.As expected,PA/TRZ-POP membrane shows a more excellent water flux of 1414 L·m^(-2)·h^(-1)·MPa^(-1)than that of the state-of-the-art nanofiltration membranes,and without sacrificing dye rejection.The build of TRZPOP interlayer develops a new method for obtaining a high-flux nanofiltration membrane.

Pilot-scale acetone-butanol-ethanol fermentation from corn stover

Biobutanol is an advanced biofuel that can be produced from excess lignocellulose via acetone-butanol-ethanol(ABE)fermentation.Although significant technological progress has been made in this field,attempts at largescale lignocellulosic ABE production remain scarce.In this study,1m^(3)scale ABE fermentation was investigated using high inhibitor tolerance Clostridium acetobutylicum ABE-P1201 and steam-exploded corn stover hydrolysate(SECSH).Before expanding the fermentation scale,the detoxification process for SECSH was simplified by process engineering.Results revealed that appropriate pH management during the fed-batch cultivation could largely decrease the inhibition of the toxic components in undetoxified SECSH to the solventogenesis phase of the ABE-P1201 strains,avoiding“acid crash”.Therefore,after naturalizing the pH by Ca(OH)_(2),the undetoxified SECSH,without removal of the solid components,reached 17.68±1.30 g/L of ABE production with 0.34±0.01 g/g of yield in 1 L scale bioreactor.Based on this strategy,the fermentation scale gradually expanded from laboratory-scale apparatus to pilot-scale bioreactors.Finally,17.05±1.20 g/L of ABE titer and 0.32±0.01 g/g of ABE yield were realized in 1m3 bioreactor,corresponding to approximately 145 kg of ABE production from 1 t of dry corn stover.The pilot-scale ABE fermentation demonstrated excellent stability during repeated operations.This study provided a simplified ABE fermentation strategy and verified the feasibility of the pilot process,providing tremendous significance and a solid foundation for the future industrialization of second-generation ABE plants.

Environmental and economic assessment of vegetable oil production using membrane separation and vapor recompression

Solvent extraction of crude oil from oilseeds is widely applied for its high production capacity and low cost. In this process, solvent recovery and tail gas treatment are usually performed by adsorption, paraffin scrubbing, or even cryogenics （at low tail gas flow rates）. Membrane separation, which has a lower energy consumption than these techniques, spans a broad range of admissible concentrations and flow rates, and is moreover easily combined with other techniques. Vapor recompression has potentials to reduce the heat loss in association with distillation and evaporation. In this study, we proved the possibility of combining membrane separation and vapor recompression to improve the conventional vegetable oil production, by both experiments and process simulation. Nearly 73% of energy can be saved in the process of vegetable oil extraction by the novel processing approach. By further environmental assessment, several impact categories show that the optimized process is environmentally sustainable.

Study on the microwave-assisted extraction of polyphenols from tea

This study demonstrated a promising method for quickly extracting tea polyphenol(TP)by microwaveassisted extraction(MAE)technology.Some influential parameters,including MAE temperature,microwave power,concentration of extraction solvent,MAE time and the solid/liquid ratio,were investigated.The optimum condition of MAE was obtained by dual extraction with 60%ethanol(v/v)and the solid/liquid ratio 1:12 g/mL at 80℃ for 10 minutes under the microwave power 600W.The yield of TP was 96.5%under the described condition.Compared with traditional methods,including hot reflux extraction(HRE),ultrasound-assisted extraction(UAE)and supercritical fluid extraction(SFE),the extraction time was saved 8 times than that of HRE,and the yield was increased by 17.5%.The extraction time at comparable levels of production was saved 2 times,and the energy consumption was one fourth that of UAE.The extraction time was saved 5 times than that of SFE,and the yield of TP was increased by 40%.Moreover,compared with MAE of TP studied by others,it decreased the solid/liquid ratio from 1∶20 to 1∶12 g/mL without 90-min pre-leaching time,and the yield of TP was increased by 6%-40%.

Separation of epigallocatechin-3-gallate from crude tea polyphenols by using Cellulose diacetate graft β-cyclodextrin copolymer asymmetric membrane

This study demonstrates a new Cellulose diacetate graft b-cyclodextrin(CDA-b-CD)copolymer asymmetric membrane prepared by a phase inversion technique for the separation of(–)-epigallocatechin-3-gallate(EGCG)from other polyphenols in crude tea.The graft copolymer,CDA-b-CD,was synthesized by pre-polymerization of cellulose diacetate(CDA)and 1,6-hexamethylene-diisocyanate(HDI),which was then grafted with b-cyclodextrin(b-CD).Surface and cross-section morphologies of the CDA-b-CD membranes were analyzed by using scanning electron microscopy(SEM).Fourier transform infrared spectroscopy(FT-IR)indicated that the b-CD was grafted onto the CDA by chemical bonding.The influences of the HDI/CDA mass ratio and the catalyst mass fraction on the b-CD graft yield were investigated.The optimum conditions of a HDI/CDA mass ratio of 0.35 g$g–1 and a catalyst mass fraction of 0.18 wt-%produced ab-CD graft yield of 26.51 wt-%.The effects of the b-CD graft yield and the concentration of the polymer cast solution on the separation of EGCG were also investigated.Under optimum conditions of a b-CD graft yield of 24.21 wt-%and a polymer concentration of 13 wt-%,the purity of EGCG increased from 26.51 to 86.91 wt-%.

Introduction to the special section on the Symposium on Computational Fluid Dynamics and Molecular Simulation

This special issue of Frontiers of Chemical Engineering in China is dedicated to the topic of Computational Fluid Dynamics(CFD)and Molecular Simulation.It features a selection of some of the best papers presented at the Symposium on CFD and Molecular Simulation,which was held in Beijing,China,on 22-23 May 2009.

Hierarchical ZnIn2S4 microspheres as photocatalyst for boosting the selective biohydrogenation of furfural into furfuryl alcohol under visible light irradiation

Photocatalyst-enzyme coupling process for visible light driven biotransformation holds promise in producing solar chemicals.In this work,aiming to produce furfuryl alcohol,the important bulk chemical that is typically derived from renewable lignocellulose,a highly selective furfural hydrogenation process is proposed by coordinating the alcohol dehydrogenase with the ZnIn2S4 assistant reduced form of nicotinamide adenine dinucleotid(NADH)regeneration.Results indicated that under visible light irradiation,the hierarchical ZnIn2S4 microspheres exhibited excellent holes and electrons separating efficiency,affording to high NADH regeneration(yield of 90.2±3.28%).When adopting the photo-biocoupled reduction process in furfural transformation,a furfuryl alcohol yield of 79.4±1.95%was achieved under the optimized conditions.The photocatalyst-enzyme coupling process also showed good stability,exceeding 70%of catalytic activity was reserved after reusing the catalysts for 10 cycles.The novel photo-biocoupled system showed promising in extending to the highly selective hydrogenation of other biochemicals from lignocelluloses.