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A series of polymeric ionic liquids (PILs) used as effective heterogeneous catalysts for biodiesel production via esterification of free fatty acids (FFAs) were effectively prepared by the reaction of poly (ethylene imine) (PEI) polymers with different molecular weight and 1,3-propanesultone, followed by the further acidification with differential effective acids, i.e. H2SO4, CF3SO3H, CH3SO3H or p-toluenesulfonic acid (p-TSA). Ultrahigh acidity and catalytic performance were achieved and could be fine-tuned by simply adjusting the molecular weight of PEI and by further treatment of acids. Specifically, under the optimal conditions (i.e. reaction temperature was 70 °C, reaction time was 2.0 h, catalyst dosage was 3.15% (mass), and alcohol/acid molar ratio was 14:1) acquired through the Box-BEHNKEN response surface methodology, a high oleic acid conversion of 98.42% could be obtained over the optimal PIL, PEI(70000)-PS-p-TSA. Additionally, our PILs also showed high generality for esterification of other FFAs, with general high conversion over 90% noted in each case even under much milder reaction conditions compared to other conventional catalysts.

Biodiesel is an attractive alternative to fossil fuels due to the energy and environmental concerns. In this paper, seven different multi –SO3H functionalized ILs based on the low-cost less-substituted amines, which contained massive sites for functionalization of sulfonic acid groups and further treatment of sulfonate-based anions, were prepared as catalysts with high acidity and desirable catalytic activity for the synthesis of biodiesel from the esterification of oleic acid with methanol. The physicochemical properties of these acidic ILs were characterized by a variety of analytical techniques such as FT-IR, EA, TGA, and the Bronsted acidity was well determined by UV–vis. Among the ILs prepared, [EDA-PS][P-TSA] showed the highest catalytic activity for esterification due to its high acidity and appropriate miscibility with reactants, with an ultrahigh 97.58% conversion of oleic acid under the optimum conditions (i.e. reaction time, 1.8 h; catalyst amount, 3 wt%; alcohol/acid molar ratio, 13:1, temperature 70 °C) acquired from the Box–Behnken response surface methodology. With the novel strategy of multi –SO3H modification on ILs, our catalyst had an approaching or even superior oleic acid conversion rate compared to other reported catalysts with considerably lower catalyst dosage and shorter reaction time. More importantly, it also exhibited high generality for converting various FFA feedstocks into biodiesel with considerable conversion within 93.59–94.33% under a rather lower catalyst dosage, which showed the valuable potential for converting low-cost oils into biodiesel from an economic and environmental perspective.

The conversion of waste cooking oil (WCO) to biodiesel is promising in the green energy and sustainable development sector. In this study, ionic liquid@amphiphilic silica nanoparticles (IASNPs) com...

Unusual self-solidifying tris(2,4,6-trimethoxyphenyl)phosphonium-containing ionic liquids were synthesized for biodiesel production via the catalytic esterification of a variety of free fatty acids...

Via the crosslinking of chitosan and sulfosuccinic acid (SSA), the acidic chitosan membrane (ACM) was prepared for biodiesel production from esterification of oleic acid and methanol. ATR-FTIR, TGA, XRD, SEM and EDX were applied to characterize the prepared ACM. The acidic site density and swelling capacity of the prepared ACM were investigated. The ACM possessed the 4.62 mmol/g of acidic site density, which was just a little less than 4.76 mmol/g of Amberlyst-15, meanwhile, ACM was proven to be much higher than Amberlyst-15 in swelling capacity. Under the same reaction, the 98.76% of conversion can be obtained while the Amberlyst-15 only reached 44.30%. The optimization of process variables was conducted by the combination of single factor experiment and Box-Behnken design (BBD) response surface methodology. The catalytic activity of ACM in different esterification of fatty acids and alcohols was also investigated. And the catalytic mechanism of esterification catalyzed by ACM was clarified. Based on the catalytic mechanism, the kinetic model was established to describe the esterification and obtain relevant kinetic parameters (Ea+, Ea−, A+ and A-), meanwhile, the kinetic results were compared to the same reaction with different catalysts in detail. Besides, the reusability of the prepared ACM was studied.

This study aimed to develop a model incorporating axillary tail position on mammography (AT) for the prediction of non-sentinel Lymph Node (NSLN) metastasis in patients with initial clinical node positivity (cN+).The study reviewed a total of 257 patients with cN+ breast cancer who underwent both sentinel lymph node biopsy (SLNB) and axillary lymph node dissection (ALND) following neoadjuvant chemotherapy (NAC). A logistic regression model was developed based on these factors and the results of post-NAC AT and axillary ultrasound (AUS).Four clinical factors with p0.1 in the univariate analysis, including ycT0(odds ratio [OR]: 4.84, 95% confidence interval [CI]: 2.13-11.91, p0.001), clinical stage before NAC (OR: 2.68, 95%CI: 1.15-6.58, p=0.025), estrogen receptor (ER) expression (OR: 3.29, 95%CI: 1.39-8.39, p=0.009), and HER2 status (OR: 0.21, 95%CI: 0.08-0.50, p=0.001), were independent predictors of NSLN metastases. The clinical model based on the above four factors resulted in the area under the curve (AUC) of 0.82(95%CI: 0.76-0.88) in the training set and 0.83(95% CI: 0.74-0.92) in the validation set. The results of post-NAC AUS and AT were added to the clinical model to construct a clinical imaging model for the prediction of NSLN metastasis with AUC of 0.87(95%CI: 0.81-0.93) in the training set and 0.89(95%CI: 0.82-0.96) in the validation set.The study incorporated the results of post-NAC AT and AUS with other clinal factors to develop a model to predict NSLN metastasis in patients with initial cN+ before surgery. This model performed excellently, allowing physicians to select patients for whom unnecessary ALND could be avoided after NAC.

To prepare polymer supported ionic liquids (PSILs) as effective catalysts for esterification, the free radical suspension copolymerization of vinylbenzyl chloride (VBC, monomer), styrene (St, monomer) and divinylbenzene (DVB, crosslinker) with the addition of n-heptane (porogen) was carried out for the fabrication of the porous polymer (PVD) microsphere as support, followed by the immobilization of sulfonic acid-functionalized ionic liquids by the successive treatment of benzimidazole (BIm), 1,3-propane sultone and sulfuric acid (H2SO4) or trifluoromethanesulfonic acid (CF3SO3H). The effects of the compositions of DVB and n-heptane on the internal structure of the polymer supports were investigated, and it was found that the support with 40 wt% DVB and 60 wt% n-heptane (with relative to the monomer) could endow the final PSILs with the relatively optimal catalytic performance. The preliminary experiment in the batch reactor indicated that PSILs herein exhibited higher catalytic activities than commercial Amberlyst 46 resin for the esterification of propanoic acid (PROAc) with n-propanol (PROOH). Consequently, the optimal PSILs catalyst, PVD-[Bim-SO3H]HSO4, was selected for further study in the batch reactive distillation column because of low cost and its ease of preparation. The yield of propyl ropionate (PROPRO) could reach up to 97.78% at the optimized conditions of PROOH/PROAc molar ratio (2:1) and catalyst dosage (2.0 wt%). The investigation of the reaction kinetic manifested that the calculated results of second order pseudo-homogeneous kinetic model were in good agreement with experimental values. The pre-exponential factor and activation energy were 4.12 × 107 L·mol−1·min−1 and 60.57 kJ·mol−1, respectively. It is worth noting that the PSILs catalyst could be simply recovered and reused with relatively satisfactory decrease in the catalytic activity, which made it an environmental friendly and promising catalyst in the industrial application.

Different from the common ionic liquids (ILs) as homogeneous catalysts, solid ionic liquids (SILs) as heterogeneous catalysts are simply fabricated herein via an efficient one-step reaction for biodiesel production. Specifically, low-cost aliphatic amines containing secondary and/or primary amine groups are selected as the starting materials followed by the reaction with 1,3-propane sultone under mild conditions to graft sulfonic acid (–SO3H) groups onto the final products. The –SO3H groups are divided into two types: the bonding –SO3H groups (zwitterion arising from the hydrogen bond between sulfonic acid groups and amine groups) make the products turn solid while the free –SO3H groups endow the products with catalytic activity. Such solid ionic liquids (SILs) present pronounced activity, excellent stability and reusability as heterogeneous catalysts in esterification of free fatty acids (FFAs), indicating great potential in biodiesel production because of their high performance and low cost.

With the combination of molecular simulation and relevant experiments, the efficient Bronsted-Lewis acidic ionic liquid (IL) was designed and synthesized for biodiesel production from soapberry oil. In molecular simulation, 4-methylthiazole (MT) is proved to be the best matrix for IL preparation via electrostatic potential analysis and proton affinity analysis, and it also is verified by experiments. In orthogonal experiment, the relationship in catalytic activity between Bronsted-Lewis acidic IL and corresponding materials (Bronsted acidic IL and metal chloride) was revealed. Meanwhile, [Ps-MTH][CF3SO3] and FeCl3 are verified as the best materials for preparation of Bronsted-Lewis acidic IL, and [Ps-MTH][CF3SO3]-FeCl3(x = 0.65) is determined as the most efficient catalyst in the end. The Lewis acidity, Bronsted acidity and interaction of [Ps-MTH][CF3SO3] and FeCl3 in [Ps-MTH][CF3SO3]-FeCl3(x = 0.65) were characterized by FT-IR. And the catalytic mechanism of transesterification catalyzed by prepared IL was clarified. In order to maximize the biodiesel yield, optimization of process variables was conducted using Box-Behnken response surface methodology. The 97.04% of high biodiesel yield is obtained under the optimum conditions: reaction temperature was 127 °C, molar ratio (methanol to soapberry oil) was 27.96:1, catalyst amount was 3.06 mmol and reaction time was 8 h. Furthermore, [Ps-MTH][CF3SO3]-FeCl3(x = 0.65) presents good catalytic activity in different transesterification for biodiesel production. And its catalytic activity decreases from 97.04% to 93.59% after being used for 5 times, which reflects good reusability. The main properties of soapberry biodiesel were also measured and compared to the ASTM D6751 standard.

This paper reports the preparation of mixed matrix membranes (MMMs) by incorporating a two-dimensional zeolitic imidazolate framework-L (ZIF-L) into a highly gas permeable hydroxyl group-containing polyimide (PI) for hydrogen separation. ZIF-L has a leaf-shaped morphology with excellent CO2 adsorption properties due to strong interaction between ZIF-L and CO2 molecules. The dispersion of ZIF-L crystals in the polymer phase increased CO2 adsorption and restricted CO2 transport through MMMs, resulting in a significant increase of H2 selectivity over CO2. The gas transport properties of MMMs with a ZIF-L loading up to 20 wt% were investigated, and the results showed such MMMs had a H2 permeability of 260 Barrers and ideal H2/CO2 selectivity of 13.4 at room temperature. The membranes presented here have the potential for large-scale fabrication for hydrogen separation applications.

Laminate graphene oxide (GO) membranes have received increasing attention recently in the water processing field due to their unique properties. However, the hydration of hydrophilic graphene oxide nanosheets leads to instability of GO membranes in aqueous solutions. In this study, ethylenediamine (EDA) was employed to crosslink GO nanosheets in a GO membrane supported on a brominated polyphenylene oxide (BPPO). In addition, because the O˭C-OH group of GO reacted with the amine group of EDA, the GO layer was firmly bonded to the BPPO substrate, as evidenced by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). EDA crosslinking dramatically improved the stability of the GO membranes. After immersion in water for one month, the prepared BPPO/EDA/GO membranes still retained their flux rates and salt rejection capabilities. The water flux rates and salt rejection capabilities of BPPO/EDA/GO membranes can be tuned by controlling GO loading. At a GO loading of 65 mg/m2, the BPPO/EDA/GO membrane achieved a relatively high water flux rate of 4.1 L/m2 h under a very low transmembrane pressure of 1 bar. Additionally, the salt rejection percentages of Na2SO4, MgSO4 and NaCl were 56.2%, 48% and 36.3%, respectively. Moreover, the BPPO/EDA/GO membrane displayed good antifouling and antibacterial properties.

Novel triazolium-based ionic liquids (ILs) have been designed and synthesized for the transesterification of palm oil with methanol to produce biodiesel. It is found that triazolium-based ILs herein possessed better thermal stability and higher catalytic activity than the common imidazolium-based ILs. The investigation of reaction condition is conducted for the optimization of the biodiesel production. The yield of biodiesel can therefore reach up to 99.75% under optimal reaction conditions. The reaction kinetic study indicated that pseudo first-order reaction kinetic model is available for the reaction system herein, and the activation energy (Ea) is 86.48 kJ·mol− 1usingthe optimal catalyst.

Effective extraction of useful resources from high-salinity textile wastewater is a critical pathway for sustainable wastewater management. In this study, an integrated loose nanofiltration-electrodialysis process was explored for simultaneous recovery of dyes, NaCl and pure water from high-salinity textile wastewater, thus closing the material loop and minimizing waste emission. Specifically, a loose nanofiltration membrane (molecular weight cutoff of ~800 Da) was proposed to fractionate the dye and NaCl in the high-salinity textile wastewater. Through a nanofiltration-diafiltration unit, including a pre-concentration stage and a constant-volume diafiltration stage, the dye could be recovered from the high-salinity textile wastewater, being enriched at a factor of ~9.0, i.e., from 2.01 to 17.9 g·L−1 with 98.4% purity. Assisted with the subsequent implementation of electrodialysis, the NaCl concentrate and pure water were effectively reclaimed from the salt-containing permeate coming from the loose nanofiltration-diafiltration. Simultaneously, the produced pure water was further recycled to the nanofiltration-diafiltration unit. This study shows the potential of the integration of loose nanofiltation-diafiltration with electrodialysis for sufficient resource extraction from high-salinity textile wastewater.

Diffusion dialysis (DD) employing anion exchange membranes (AEMs) presents an attractive opportunity for acid recovery from acidic wastewater. However, challenges exist to make highly acid permeable AEMs due to their low acid dialysis coefficient (Uacid). Here, a series of porous and highly acid permeable AEMs fabricated based on chloromethyl polyethersulfone (CMPES) porous membrane substrate with crosslinking and quaternization treatments is reported. Such porous AEMs show high Uacid because of the large free volume as well as the significantly reduced ion transport resistance relative to the dense AEMs. Compared with the commercial dense DF-120 AEM, our optimal porous AEM show simultaneous 466.7% higher Uacid and 75.7% higher acid/salt separation factor (Sacid/salt) when applied to acid recovery at the same condition. Further, considering the simple and efficient fabrication process as well as the low cost, our membranes show great prospects for practical acid recovery from industrial acidic wastewater.

Asymmetrically porous anion exchange membranes for acid recovery by diffusion dialysis are prepared by one-step functionalization of chloromethylated polysulfone (PSF) ultrafiltration membrane via reaction with N,N,N′,N′-tetramethyl-1,3-propanediamine (TMPDA) to achieve simultaneous crosslinking and quaternization. The performance of the resulting TMPDA modified PSF (TPSF) membranes can be easily tailored by controlling the reaction time in TMPDA solution and thus the charged density and crosslinking degree. The TPSF membranes exhibit excellent diffusion dialysis performance, especially high acid dialysis coefficient, stemming from the porous matrix and thin selective layer ( −1 and a separation factor of 34.0, which are 6.6 and 0.84 times greater than the corresponding values of the commercial DF-120 membranes at the same testing condition using a mixture of HCl and FeCl 2 solution as feed solution. The membranes reported in this work are promising for scale-up for industrial acid recovery applications.

Graphene and its derivatives are very attractive for constructing membranes for high-efficiency separation applications including water purification and desalination. To develop practical desalination membranes, strictly controlled inter-layer distance of graphene-based laminates and strong adhesion of graphene-based selective layers onto a porous polymer substrate are required to provide high salt rejection properties and desirable mechanical durability with chlorine tolerance in membrane processes. However, there is a difficulty in stabilizing graphene nanosheets as a membrane selective layer for the desalination process and controlling their interlayer distance. In this work, we demonstrate the successful fabrication of a graphene-based thin-film composite membrane by integrating graphene oxide (GO) nanosheets into a highly crosslinked polymer network on a porous polymer substrate. The resulting poly(N-isopropylacrylamide-co-N,N′-methylene-bisacrylamide) entwined GO thin-film composite membrane has a main GO interlayer spacing of 0.48 nm and a GO–polymer thin film of less than 40 nm thick and shows excellent water flux (25.8 L m−1 h−1) and salt rejection (a NaCl rejection of 99.9%), alongside excellent mechanical stability and chlorine tolerance for the forward osmosis process. This polymer network entwined GO thin-film composite can be effectively tailored as a platform material for developing high-performance osmosis desalination membranes for industrial application.

Three-dimensional (BiO)2CO3 (BSC) nanostructures were synthesised by a hydrothermal reaction, and Bi2O3 nanoparticles were then obtained by calcining BSC precursor at different temperatures. BSC and Bi2O3 samples were then sputtering coated with Au to get the resultant Au/BSC and Au/Bi2O3 for the investigation of the effect of the Au coating on the photocatalytic performance of the samples. The phase structure, morphology and composition of the samples were characterised by X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy (EDS). UV–vis diffuse reflectance spectra were used to measure the response of different catalysts to UV–vis light. The photocatalytic activity was investigated for the degradation of rhodamine 6G at room temperature and the light intensity was 1 sun. Bi2O3 exhibited better photocatalytic performance than BSC due to the narrow band gap of Bi2O3, and the coating of Au also endowed the samples with higher photocatalytic capability as compared to th...

In the sustainability concept framework, wastewater highly loaded with acid is considered as a valuable resource, rather than a waste. Diffusion dialysis employing anion exchange membranes is a feasible solution to extracting acid from this waste stream. However, conventional anion exchange membranes have dense spatial structures with no observable pores even at nanoscale, which limits the transfer of protons. Porous anion exchange membranes provide a practical avenue to enhance the proton transfer due to their unique spatial structure. In this study, novel porous anion exchange membranes were designed by one-step crosslinking and quaternization of porous brominated poly (phenylene oxide) membrane substrate by 1, 4-diazabicyclo [2.2.2] octane. The resultant porous anion exchange membranes showed a high performance in acid recovery by diffusion dialysis, due to their uniquely tailored microstructures including an extremely thin selective layer and high free space volume. Specifically, the optimal anion exchange membrane possessed an acid dialysis coefficient of 0.066 ± 0.003 m h−1 and an acid/salt separation factor of 96.9 ± 2.5 in the HCl/FeCl2 mixture solution, outperforming the commercial anion exchange membrane (i.e., DF-120, acid dialysis coefficient of 0.0085 m h−1 and acid/salt separation factor of 18.5). This study demonstrates the great potential in constructing advanced anion exchange membranes at large scale for efficient acid recovery from highly acidic wastewater to support environment sustainability.

Polymeric self-solidifying ionic liquids (PSILs) were simply fabricated by the facile nucleophilic substitution reaction between polyethyleneimine (PEI) and 1,3-propanesultone (PS). Because of the presence of less-substituted amino groups in PEI chain, more than 1 equivalents of sulfonic groups (–SO3H) per amino group were grafted onto PEI chain. Part of –SO3H groups could be bonded with amino groups to form –SO3–…N+– zwitterions, the presence of zwitterion and the high molecular of PEI could make PSILs become solid, while the left free –SO3H groups played a role in the acid catalysis and therefore no additional acids were required. The final PSILs showed high catalytic activity, stability and generality as the heterogeneous catalysts for biodiesel production via the esterification of a variety of free fatty acids (FFAs), as well as the transesterification of waste cooking oil and palm oil. Moreover, the one-step fabrication process of PSILs is much simpler than the multi-step fabrication process of traditional ionic liquids, suggesting potential benefits.

Diffusion dialysis for acid recovery from acidic waste solution suffers from the low process capacity due to low proton permeability of current dense anion exchange membranes. In this work, asymmetrically porous ultrafiltration membranes with a thin skin layer (e.g.

To selectively remove heavy metal from dye solution, inspired by the unique pore structure of ZIF-8, we developed a synthetic strategy for rapid construction of ZnO@ZIF-8 heterostructure photocatalyst for selective reduction of Cr(VI) between Cr(VI) and methylene blue (MB). In particular, ZnO@ZIF-8 core-shell heterostructures were prepared by in situ ZIF-8 crystal growth using ZnO colloidal spheres as template and zinc source within 8-60 min. The shell of the resulting ZnO@ZIF-8 core-shell heterostructure with a uniform thickness of around 30 nm is composed of ZIF-8 crystal polyhedrons. The concentration of organic ligand 2-methylimidazole (Hmim) was found to be crucial for the formation of ZnO@ZIF-8 core-shell heterostructures. Different structures, ZnO@ZIF-8 core-shell spheres and separate ZIF-8 polyhedrons could be formed by altering Hmim concentration, which significantly influences the balance between rate of Zn(2+) release from ZnO and coordinate rate. Importantly, such ZnO@ZIF-8 core-shell heterostructures exhibit size-selective photocatalysis properties due to selective adsorption and permeation effect of ZIF-8 shell. The as-synthesized ZnO@ZIF-8 heterostructures exhibited enhanced selective reduction of Cr(VI) between Cr(VI) and MB, which may find application in the dye industry. This work not only provides a general route for rapid fabrication of such core-shell heterostructures but also illustrates a strategy for selectively enhanced photocatalysis performance by utilizing adsorption and size selectivity of ZIF-8 shell.

To enhance the proton permeability of the anion exchange membranes used in diffusion dialysis, porous ultrafiltration membrane with a thin skin layer rather than the dense membrane was utilized for the preparation of diffusion dialysis membrane. In particular, brominated poly (phenylene oxide) (BPPO) ultrafiltration membrane was fabricated via a phase inversion method and then modified by crosslinking with polyethyleneimine (PEI) and subsequent quaternization with trimethylamine (TMA) via nucleophilic substitution reaction. Diffusion dialysis related properties of the membranes such as water uptake, ion exchange capacity, and thermal and swelling stabilities were investigated. Due to the special structure of the membranes (i.e., high porosity and low thickness of the top layer (sub-1 μm), as confirmed by scanning electron microscopy) the optimal membrane exhibited 6.4 times higher acid dialysis coefficient for HCl recovery from HCl/FeCl2 solution than the commercial DF-120 (thickness=320 μm) membrane at the similar separation factor. The calculated acid recovery capacity can increase from 11.3 up to 83.7 L m−2 d−1 by replacing DF-120 with our optimal membrane. Our findings show the porous membranes developed here have great potential for high-efficiency acid recovery through diffusion dialysis process.

A series of self-solidifying hybrid ionic liquids (SHILs) were synthesised via a mild nucleophilic substitution reaction between (3-aminopropyl)trimethoxysilane and 1,3-propanesultone followed by a facile sol-gel reaction, during which not any acid, catalyst or support was introduced. Part of the grafted –SO3H groups would make SHILs become solid nature by forming the zwitterion, while the rest of –SO3H groups could endue SHILs with acidic catalytic sites. Besides, –Si–O–Si– networks formed by the sol-gel reaction would further impart the water-tolerance and heterogeneity to SHILs, conducive to the easy separation and good reusability. For the oleic acid esterification catalysed by P-APTMS-PS-5 SHIL, 96.55% conversion was achieved under appropriate conditions (optimised by response surface methodology), and the catalytic activity well remained after 7 cycles. More importantly, SHILs exhibited excellent catalytic activity and satisfactory generality in the esterification of various free fatty acids, as well as in the transesterification of different oils, signifying the great potential for biodiesel production.

Effective fractionation of dyes and salts (NaCl) potentially paves a new path to sustainable treatment of textile wastewater. Herein, a loose nanofiltration (NF) membrane was innovatively used as the anion conductive membrane in electrodialysis (ED) for dye and salt separation. The NF membrane with a molecular weight cut-off of 678 Da showed a sufficient retention for reactive dyes with small molecular weights (

Novel quaternized membranes with zwitterionic groups applied in all-vanadium redox flow battery (VRB) have been prepared using a solvent free strategy, which is environmentally-friendly and different from traditional methods using organic solvents as reaction media. It was performed by dissolving cardopolyetherketone (PEK-C) in monomers mixture of 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB), and then in situ polymerization to incorporate PEK-C into the network of poly (VBC–DVB). The resulting copolymer was immersed in dimethylamine (DMA) followed by 1,3-propane sultone (PS) aqueous solution to obtain the target quaternized membranes bearing zwitterionic groups ([ CH 2 N + (CH 3 ) 2 CH 2 CH 2 CH 2 SO 3 − ]), which greatly enhance the chain packing density, and consequently improve membrane stability. The optimized quaternized membrane with zwitterionic groups showed a 20% decrease in vanadium ion permeability as compared to the benchmark quaternized membrane without zwitterionic groups. It also possesses good mechanical strength even after immersion in VO 2+ solution for as long as 20 days. Comparing the commercial Nafion117 with the optimized membrane, the vanadium ion permeability sharply decreased from 10.80×10 −5 cm min −1 to 0.21×10 −5 cm min −1 while the coulombic and energy efficiency increased from 89.7% and 68.3% to 97.1% and 73.4% at 50 mA cm −2 , respectively. The present quaternized membrane with zwitterionic groups shows good characteristics for application in VRBs.

To overcome the low solubility of salicylic acid (SAH) in the production process by bipolar membrane electrodialysis (BMED), the water–ethanol mixture as solution medium was introduced in the BMED technique. The results indicated that the highest acid concentration was obtained when ethanol content was 50 v/v%, and the current efficiency reached 98.2%. Moreover, the BMED stack of BP–C (BP, bipolar membrane; C, cation exchange membrane) configuration was proved as most cost-effective configuration, and using this configuration the highest current efficiency could reach 99.6% and the lowest energy consumption was 2.1 kW h kg−1.

Novel ultrafiltration (UF) membranes were prepared by blending brominated poly(phenylene oxide) (BPPO) and its quaternary phosphonium derivative (TPPOQP-Br) as additive using a phase inversion method. The chemical structure and microstructure of the membranes were characterized by Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The XPS results indicated that the BPPO/TPPOQP-Br composite membranes exhibited an increase in the concentration of TPPOQP-Br from the top surface to the bottom surface. In contrast, the composite membranes prepared from BPPO and its quaternary ammonium derivative (TPPOQA-Br) showed an opposite concentration gradient of TPPOQA-Br. This was attributed to the difference in wettability and hydration rate between TPPOQP-Br and TPPOQA-Br, leading to different membrane microstructure and chemical composition distributions. BPPO membrane showed a water flux of 215 L m −2 h −1 at 100 kPa and its molecular weight cut-off of PEG is 93.8 kDa; the corresponding values of the optimal BPPO/TPPOQP-Br membrane are 873 L m −2 h −1 and 111.3 kDa, both of which are better than those of BPPO/TPPOQA-Br with the similar additive loading (381 L m −2 h −1 and 150.2 kDa). Therefore, the addition of TPPOQP-Br significantly enhances the water permeability while maintaining the excellent rejection properties in the resultant UF membranes. This work extends the choice of the additives in the UF membrane fabrication, and further proves that the addition of hydrophobic and charged polymer with slow hydration property is an effective strategy for improving flux and anti-biofouling properties of UF membranes.

Tris(2,4,6-trimethoxyphenyl)polysulfonemethylene quaternary phosphonium chloride (TPQP-Cl) was blended with polysulfone (PSf) in different compositions to fabricate PSf/TPQP-Cl composite ultrafiltration membranes using the nonsolvent-induced phase separation method. The blending of polymers was confirmed by attenuated total reflectance infrared (ATR-IR) spectroscopy. Surface and cross-sectional morphologies of membranes were characterized using scanning electron microscopy (SEM). The SEM images showed that the PSf/TPQP-Cl membranes had a typical asymmetric structure. The X-ray photoelectron spectroscopy (XPS) and contact angle analysis revealed the enrichment of TPQP-Cl in the supporting layer of the membrane. In addition, water content, porosity, contact angle, pure water flux, and molecular weight cutoff were measured to study the influence of addition of TPQP-Cl. In particular, the addition of TPQP-Cl led to greatly increased water flux without significantly increased molecular weight cutoff; the PSf/TPQP-Cl membranes exhibited up to 7.3 times higher water flux than the pure PSf membrane at similar rejection properties. This work provides an effective way to tailor ultrafiltration membrane structure to achieve high flux while maintaining rejection properties.

Anion exchange membranes with fast acid permeation and high retention of salts are urgently needed to increase the process efficiency of acid recovery from various industrial processes via diffusion dialysis, thereby greatly reducing their energy consumption and environmental impact. In this work, we have developed a novel one-step method of simultaneous crosslinking and quaternization for the fabrication of high-performance diffusion dialysis membranes. As an example, porous brominated poly(phenylene oxide) (BPPO) ultrafiltration membranes with a thin active layer (

Polymer ultrafiltration membranes with high water flux have long been pursued to improve filtration efficiency and reduce costs of industrial separation processes such as water treatment and food processing. However, increasing water flux is usually accompanied by decreased rejection property in these membranes. In this paper, we show that by using a polymer functionalized with hydrophobically ionizable groups as additive, polymer ultrafiltration membranes with an increasing concentration of the additive from the active layer to the supporting layer are produced in the membrane casting process due to slow hydration of the additive. The hydrated additive becomes hydrophilic after the membrane formation. The resulting membranes exhibit dramatically enhanced water permeability while maintaining excellent separation property. We demonstrate that polyethersulfone/tris(2,4,6-trimethoxyphenyl)polysulfone-methylene quaternary phosphonium chloride (PES/TPQP-Cl) membrane exhibits a water permeability of up to 14.6 l m −2 h −1 kPa −1 , which is 35 times that of PES membrane. The membrane also shows excellent anti-biofouling property. The work provides a new methodology for designing high-performance membranes for improving separation efficiency and exploring other novel applications.

Cation exchange membranes (CEMs) have been prepared from sulfonated poly(phenylene oxide) (SPPO) by electrospinning and hot-press treatment. Effect of various parameters, such as concentration, voltage and tip to collector distance (TCD) as well as the hot-press treatment conditions on properties of membrane has been fully investigated. When being applied in diffusion dialysis (DD) for alkali recovery from Na 2 WO 4 /NaOH solution, the membrane exhibits higher hydroxide permeability ( U OH , 0.00971 m/h) and separation factor ( S , 36.09) than the solution casting SPPO membrane (CSPPO), of which U OH is only 0.00605 m/h and S is 21.8. Compared with previously reported DD membranes with U OH in the range of 0.0014–0.0022 m/h, Hot-pressed Electrospun SPPO (H-ESPPO) shows approx. 4 times higher in U OH , underling its superior performance in DD application.

The development of anhydrous proton-conductive membranes operating at temperatures above 100 °C is a challenge for practical application. To meet the requirements, the N-(3-aminopropyl)-imidazole (NAPI), a proton-carrier molecule, is encapsulated in the frameworks of the Fe-MIL-101-NH 2 and then allowed to react with sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO) for preparing hybrid proton conductive membrane. Results showed that the dispersed proton conductive metal–organic frameworks (MOFs) in the membrane provide a convenient pathway for proton mobility under high temperature and anhydrous condition. Tuning of the host–guest interaction can generate a good proton-conducting pathway at temperatures above 150 °C. It is also presumed that the proton transfer in the membrane is simultaneously contributed from the Grotthuss-type mechanism and the vehicle-type mechanism. This work suggests that a combination of guest molecules and microporous frameworks could afford highly mobile proton carriers in solids. Therefore, the new proton conductive membranes can be designed by incorporating the MOFs into functionalized polymers for applications at high temperature and anhydrous condition.