Acid Dialysis Coefficient Research Articles

Mechanism underlying anion-sieving in poly(ionic liquid)-based membrane: Effective acid recovery from engineering waste

Anion exchange membranes (AEMs) are promising for recovering acid from different engineering effluent due to their lower energy consumption, positive environmental impact, and potential for providing clean water resources. Utilizing the diffusion dialysis (DD) process, AEMs effectively retain metal ions while selectively allowing fast proton permeation. Achieving high hydrophilicity, proton conductivity, and ion exchange capacity through exact control of polymeric structure and chemical composition is crucial for enhancing the efficiency of the acid recovery process. This study presents the findings on the impact of novel Poly(ionic liquid) on cellulose acetate-based AEMs for acid recovery through DD application. In this study, interconnected nanochannel AEMs with high acid permeability are engineered using a straightforward blending technique. Poly(3-butyl-1-vinylimidazolium bromide-co-methyl methacrylate-co-styrene) (poly([BVIM]-[Br]–co–MMA-co-Styrene, PIL) is blended with cellulose acetate to achieve ionic crosslinking, resulting in a mechanically stable membrane. The dosage of PIL within the membrane matrix plays a vital role in determining the prepared membranes' physicochemical properties and ion exchange capabilities, which exhibit excellent thermal stability. Remarkably, the optimal AEM (7.5 % PILM) exhibits a high acid dialysis coefficient (UH+) of 1.05 m/h and a separation factor (S) of 802, outperforming previously reported state-of-the-art AEMs and commercial membranes. These findings indicate that the prepared AEMs are highly effective for acid recovery through DD. Notably, our work stands out by introducing new AEMs with superior acid dialysis performance and selectivity.

Semi-Interpenetrating Polymer Network Anion Exchange Membranes Based on Quaternized Polybenzoxazine and Poly(Vinyl Alcohol-Co-Ethylene) for Acid Recovery by Diffusion Dialysis.

Acid recovery from acidic waste is a pressing issue in current times. Chemical methods for recovery are not economically feasible and require significant energy input to save the environment. This study reported a semi-interpenetrating polymer network (semi-IPN) anion exchange membranes (AEMs) for acid recovery by diffusion dialysis with excellent dimensional stability, high oxidation stability, good acid dialysis coefficient (UH +) and high separation factor (S). Semi-IPN AEMs are prepared by ring-open cross-linked quaternized polybenzoxazine (AQBZ) with poly(vinyl alcohol-co-ethylene), where AQBZ is obtained by Mannich reaction and Menshutkin reaction. All four proportions of semi-IPNs exhibit clear micro-phase separation, which is conducive to ion transport. The water uptake (WU) of the four semi-IPNs ranges from 14.2 % to 19.2 %, while the swelling ratio (SR) remains between 8.7 % and 11.3 %. These results indicate that the cross-linked structure in the designed semi-IPNs effectively control swelling and ensure dimensional stability. The thermal degradation temperature (Td5) of semi-IPN4:6 to semi-IPN7:3 varies from 309 °C to 289 °C, with an oxidation stability weight loss rate (WOX) ranging from 91.5 % to 93.5 %, demonstrating excellent thermal stability and oxidation stability. The semi-IPNs also show good UH + values ranging from 11.9-16.3*10-3 m/h and high S values between 38.6 and 45.9, indicating the promising potential of the semi-IPNs.

A simple method to prepare anion exchange membrane by PVA/EVOH/MIDA for acid recovery by diffusion dialysis.

Given the substantial environmental pollution from industrial expansion, environmental protection has become particularly important. Nowadays, anion exchange membranes (AEMs) are widely used in wastewater treatment. With the use of polyvinyl alcohol (PVA), ethylene-vinyl alcohol (EVOH) copolymer, and methyl iminodiacetic acid (MIDA), a series of cross-linked AEMs were successfully prepared using the solvent casting technique, and the network structure was formed in the membranes due to the cross-linking reaction between PVA/EVOH and MIDA. Fourier transform infrared spectrometer, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to analyze the prepared membranes. At the same time, its comprehensive properties which include water uptake, linear expansion rate, ion exchange capacity, thermal stability, chemical stability, and mechanical stability were thoroughly researched. In addition, diffusion dialysis performance in practical applications was also studied in detail. The acid dialysis coefficient (UH+) ranged from 10.2 to 35.6 × 10-3 m/h. Separation factor (S) value ranged from 25 to 38, which were all larger than that of the commercial membrane DF-120 (UH+: 8.5 × 10-3 m/h, S: 18.5). The prepared membranes had potential application value in acid recovery.

Simple and low-cost anion exchange membrane based on PVA and PDC for acid recovery by diffusion dialysis

Anion exchange membranes were prepared by a simple method on the basis of polyvinyl alcohol (PVA) and 1,4-Piperazinedicarboxaldehyde (PDC). A network structure was formed in the membranes by cross-linking between PVA and PDC. The mechanical stability and acid stability the prepared membranes was tested. The TS value was tested as 17.5–37.8 MPa, Eb was 120.4–54.7% and the mass retention in the acid environment was 98.4–97.2%. Meanwhile, the physicochemical properties of membranes, such as thermogravimetric analysis (TGA), water absorption (WR), ion exchange capacity (IEC) and linear expansion rate (LER). WR was 106.9–136.7%, IEC was 1.03–1.55 mmol/g, and LER was 37.93–33.33%. In practical application, diffusion dialysis (DD) performance of membranes were tested. In DD test, the acid dialysis coefficient (UH+) was 17.5–27.9 × 10−3 m/h, and the separation factor (S) was 31.25–23.38. The UH+ and S were all higher than commercial membrane DF-120 (UH+ is 9 × 10−3 m/h and S is 18.00). Results were shown that the comprehensive properties of membranes were good. Therefore, the prepared membranes had broad application prospects for acid recovery by diffusion dialysis.

Anion exchange membranes with efficient acid recovery obtained by quaternized poly epichlorohydrin and polyvinyl alcohol during diffusion dialysis

Herein, we discussed the synthesis of quaternized poly epichlorohydrin (QPECH) by the reaction of poly epichlorohydrin (PECH) with N, N-dimethylethanolamine (DMEA). After that, different amounts of QPECH were mixed with the polyvinyl alcohol (PVA) and tetraethyl silicate (TEOS) to fabricate a series of anion exchange membranes (AEMs) by sol-gel reaction. The chemical structure of the synthesized QPECH was effectively proved by Fourier transform infrared (FTIR) and 1H NMR. Hereafter, the composite membrane structure was determined by FT-IR, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the physical and chemical properties such as thermogravimetric analysis (TGA), water uptake (WR), ion exchange capacity (IEC), linear expansion rate (LER) and diffusion dialysis (DD) were tested. The performance, such as acid recovery and selectivity of PVA/QPECH composite membranes with different QPECH content, was discussed comprehensively. The results showed that the WR of the composite membrane was 82.35–158.54%, the LER was 19.23–40.74%, and the IEC was from 0.64 to 1.76 mmol/g. In the DD test simulating waste acid recovery, the acid dialysis coefficient (UH+) was in the range of 11.1–30.0*10-3 m/h, and the separation factor (S) was 24.79–42.24. The UH+ and S of the composite membranes were all better than that of commercial membrane DF-120. In conclusion, this study demonstrated that the application of anion exchange membrane based on PVA/QPECH had the potential in acid recovery by DD method.

In-situ cross-linked porous anion exchange membranes with high performance for efficient acid recovery

Diffusion dialysis (DD) has high economic competitiveness for acid recovery; however, the fabrication of highly acid-permeable and salt-rejecting anion exchange membranes (AEMs) for DD is still a grand challenge. This paper presents in-situ cross-linked porous AEMs with tunable microstructures and high DD performance. The AEMs were fabricated based on chloromethyl polyethersulfone substrate using N, N, N′, N″, N″-pentamethyldiethylenetriamine as a bifunctional agent for cross-linking and quaternization. The prepared porous AEMs showed significantly superior DD performance over conventional dense AEMs due to the high free volume and cross-linked networks within our membranes. The acid dialysis coefficient (UH+) and acid/salt separation factor (S) of the optimal AEM were 2.6 and 255.4 times as high as those of the commercial DF-120 AEM, respectively. Therefore, our low-cost, high-performance in-situ cross-linked porous AEMs may pave the way for large-scale acid recovery applications.

Porous anion exchange membranes fabricated by phase inversion and in‐situ modification for acid recovery

AbstractDiffusion dialysis (DD) for acid recovery is significantly restricted by the poor acid dialysis coefficient () of anion exchange membranes (AEMs). To overcome such problem, porous AEMs with extremely high free space volume have been fabricated herein based on porous membrane substrate, drawing inspiration from the dissolution‐diffusion concept. Specifically, chloromethylated polyethersulfone (CMPES) has been used as the starting material to create the porous substrate via non‐solvent phase inversion, then in‐situ crosslinked and quaternized using ethylenediamine (EDA) and N‐methylimidazole (NMI), respectively. In this study, the degrees of modification of EDA and NMI are controlled to adjust the microstructure and DD performance of the produced porous AEMs. The ideal AEM's and acid/salt separation factor (S) are 4.3 and 2.6 times greater, respectively, than those of the commercial DF‐120 membrane at the same condition. Additionally, it shows strong organic solvent resistance and thermal stability, and therefore demonstrate the potential for widespread use.

Synthesis of Porous BPPO-Based Anion Exchange Membranes for Acid Recovery via Diffusion Dialysis.

Diffusion dialysis (DD) is an anion exchange membrane-based functional separation process used for acid recovery. TMA (trimethylamine) and BPPO (brominated poly(2,6-dimethyl-1,4-phenylene oxide) were utilized in this manuscript to formulate AEMs (anion exchange membranes) for DD (diffusion dialysis) using the phase-inversion technique. FTIR (Fourier transfer infrared) analysis, proton NMR spectroscopy, morphology, IEC (ion exchange capacity), LER (linear expansion ratio), CR (fixed group concentration), WR (water uptake/adsorption), water contact angle, chemical, and thermal stability, were all used to evaluate the prepared membranes. The effect of TMA content within the membrane matrix on acid recovery was also briefly discussed. It was reported that porous AEMs have a WR of 149.6% to 233.8%, IEC (ion exchange capacity) of 0.71 to 1.43 mmol/g, CR (fixed group concentration) that ranged from 0.0046 mol/L to 0.0056 mol/L, LER of 3.88% to 9.23%, and a water contact angle of 33.10° to 78.58°. The UH (acid dialysis coefficients) for designed porous membranes were found to be 0.0043 to 0.012 m/h, with separation factors (S) ranging from 13.14 to 32.87 at the temperature of 25 °C. These observations are comparable to those found in the DF-120B commercial membrane with UH of 0.004 m/h and S of 24.3 m/h at the same temperature (25 °C). This porous membranes proposed in this paper are excellent choices for acid recovery through the diffusion dialysis process.

Porous Anion Exchange Membrane for Effective Acid Recovery by Diffusion Dialysis

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.

N-cyclic cationic group-functionalized cardo poly(arylene ether sulfone)s membranes with ultrahigh selectivity for diffusion dialysis in acid recovery

To produce high-performance and durable membranes used in diffusion dialysis (DD) for acid recovery, poly(arylene ether sulfone)s containing different N-cyclic quaternary ammonium (QA) cations (CardoPES-C2-R(Cl-)) were prepared, and the relationships between the N-cyclic QAs and the properties of the corresponding membranes were explored. The CardoPES-C2-R(Cl-) membranes exhibited ultrahigh H+/Fe2+ selectivity in DD that was higher than that of a commercial DD membrane and other reported DD membranes. Most importantly, both the acid dialysis coefficient (UH+) and the H+/Fe2+ selectivity of the CardoPES-C2-R(Cl-) membranes can be readily adjusted by regulating the chemical structures of functional groups. Interestingly, because of the hydrogen bonds proven by 1H NMR, the CardoPES-C2-Mor(Cl-) membrane displayed a higher acid permeability coefficient than other N-cyclic QA cation-based membranes with identical ion exchange capacity (IEC) values, but showed lower Cl- conductivity. Additionally, the CardoPES-C2-R(Cl-) membranes exhibited excellent chemical and operational stability after aging testing and consecutive operation.

High-performance porous anion exchange membranes for efficient acid recovery from acidic wastewater by diffusion dialysis

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.

Construction of two dimensional anion exchange membranes to boost acid recovery performances

Currently, the development of two dimensional (2D) lamellar membranes for acid recovery via the diffusion dialysis process is still in its infancy. In this work, we proposed the concept of 2D anion exchange membranes (AEMs) to synergistically improve the H+ dialysis coefficient and separation factor. The 2D AEMs were fabricated by layer by layer stacking the graphene oxide nanosheets decorated by imidazolium cations (Im-GO). Benefitting from the attachment of imidazolium cations, the Im-GO membrane exhibits higher hydrophilicity and wider interlayer channels compared with the original GO membrane, favorable of quicker H+ migration. Additionally, imidazolium cations serving as typical anion exchange sites help with rapid H+ transfer and better distinguishing H+ and Fe2+ via the electrostatic exclusion mechanism. The diffusion dialysis results show that the acid dialysis coefficients gained by Im-GO (5.9 × 10−3- 8.2 × 10−3 m h−1) are an order of magnitude higher than GO (0.7× 10−3 m h−1). Ideally, Im-GO also gives rise to higher separation factors (24–37) toward H+ and Fe2+ than GO (15). Moreover, after 10 times continuing acid recovery testing, Im-GO demonstrates no declines of dialysis coefficients and separation factors. We believe the engineering strategy reported here could act as a versatile method for modifying 2D membranes, to further extend their usage scope.

Novel poly (ionic liquid)-based anion exchange membranes for efficient and rapid acid recovery from industrial waste

Owing to the less energy consumption, positive impact on the environment, and prospect of providing clean water resources, anion exchange membranes (AEMs) are promising materials for acid recovery from various industrial wastewater/effluent. Based on the diffusion dialysis process, AEMs selectively allow rapid proton permeation while efficiently retaining metal ions. To enhance the efficiency of the acid recovery process, precise control of macromolecular architecture and chemical composition that enables high hydrophilicity, proton conductivity through the membrane, and ion exchange capacity is required. In this direction, we report on the one-step fabrication of novel poly (ionic liquids)-based AEMs by the free radical polymerization of 1-butyl-3-vinyl imidazolium bromide, acrylic acid, styrene, and acrylonitrile under sunlight. The effect of monomer composition in an AEM matrix on the structural, physicochemical, surface, thermal, and proton conductivity is investigated. The experimentally determined acid dialysis coefficient (UH+) obtained with synthesized poly (ionic liquid) based membranes PILM-1 and PILM-2 were 7.3 ± 2 and 9.2 ± 2 mh−1 at room temperature (25 °C), while separation factors (SF) were 88.9 ± 3 and 50.1 ± 2, respectively. Both the UH+ (>700 times) and SF (>4 times) are significantly values higher compared to the commercial AEM DF-120 (0.009 mh−1 and 18.8 for UH+ and SF, respectively). Thus, this study demonstrates the potential of the prepared AEMs as an alternate to deliver cost-effective, scalable, and rapid acid recovery compared to the currently existing technology.

Quaternized poly(2,6-dimethyl-1,4-phenylene oxide)s with zwitterion groups as diffusion dialysis membranes for acid recovery

For the purpose of simultaneously improving H+ dialysis coefficient and selectivity between proton and metal ions in acid diffusion dialysis (DD), a series of quaternized poly(2,6-dimethyl-1,4-phenylene oxide)s (PPO) anion exchange membranes (AEMs) containing zwitterion groups were designed and synthesized via Cu(I)-catalyzed “click chemistry”. The ion exchange capacity (IEC) and degree of functional zwitterion groups were controlled readily by adjusting the amount of the reagent due to the quantitative click reaction. The electrostatic effects of zwitterionic groups provided AEMs with proper water uptake (<65 wt%), dimensional stabilities (<19%) even under elevated temperatures (60 °C) as well as robust mechanical properties. Taking the simulated iron polishing waste solution (HCl, 1.0 mol/L; FeCl2, 0.2 mol/L) for research, the diffusion dialysis performance of membranes was investigated. As expected, the zwitterionic functionalization of the membrane enhanced the H+ dialysis coefficient and selectivity simultaneously. The zwitterion groups-based membranes with a thickness of 30–40 μm showed high acid dialysis coefficient up to 0.037 m/h and selectivity up to 32.7 at 30 °C. Therefore, the introduction of zwitterionic groups into anion exchange membrane is an effective approach for the simultaneous H+ dialysis coefficient and selectivity improvement of the membrane in DD for acid recovery.

Fabrication and characterization of pyridinium functionalized anion exchange membranes for acid recovery

In the present work, the fabrication of pyridinium functionalized anion exchange membranes (AEMs) for acid recovery using diffusion dialysis (DD) processes was developed using brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO) as a polymer backbone and 4-methylpyridine (MP) as an ion exchange element. The electrochemical and physiochemical properties of the developed AEMs were tested under various concentration of MP into the polymer matrix. Water uptake (WR) of 17.18% to 30.55%, ion exchange capacity (IEC) of 1.94–2.24 mmol/g and linear swelling ratio (LSR) of 6.87–14.89% were obtained. In addition, the new membranes exhibited dense morphology, higher thermal and chemical stability in addition to dimensional and mechanical sturdiness. Acid dialysis coefficient (UH) in the range of 0.011–0.066 m/h was obtained. In addition the developed AEMs had a separation factor (S) in range of 24.87–77.61 resulting in enhanced DD performance compared to commercial membrane DF-120B under comparable experimental conditions. The new prepared membranes showed potential for successful application in acid recovery via diffusion dialysis.

Investigation of key process parameters in acid recovery for diffusion dialysis using novel (MDMH-QPPO) anion exchange membranes

Investigating the influence of operating parameters is a critical step in development of diffusion dialysis for acid recovery. A series of novel anion exchange membranes consisted of methyl 6-(dimethylamino) hexanoate (MDMH) and poly (2, 5-dimethylphenyl oxide) are successfully fabricated and used for acid recovery via DD process. Initially, the 6-(dimethylamino) hexanoic acid and MDMH are synthesized via condensation reaction and its chemical structure is confirmed by 1H NMR spectroscopy. After membranes fabrication, the chemical composition and morphological structures are confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. The MDMH-QPPO AEMs possess good acid permeability, selectivity, and outstanding thermo-mechanical stability. A synthesized membrane (MDMH-QPPO-5) with better performance of acid permeability and selectivity is selected for mathematical and statistical studies of process parameters in diffusion dialysis. The effect of process parameters including temperature, time and feed concentration are studied through full factorial design (FFD). The half normal plot is used to investigate the order of process parameters that considerably affecting the acid dialysis coefficient and separation factor. The results showed that the investigation of significant process parameters is useful to improve the acid recovery via diffusion dialysis.

Augmenting acid recovery from different systems by novel Q-DAN anion exchange membranes via diffusion dialysis

Abstract In this study, a series of novel anion exchange membranes composed of polyvinyl alcohol (PVA) and various amount of synthesized anion exchange precursor were successfully prepared and used for acid recovery by DD process. The anion exchange precursor (Q-DAN) was synthesized through reaction of 1,5-diaminonaphthalene (DAN) and 2,3-epoxypropyltrimethylammonium chloride (EPTC) which was confirmed by proton NMR. The dosage of Q-DAN inside membrane matrix played an important role to determine the electrochemical and physicochemical properties of Q-DAN AEMs. Influences of Q-DAN and multivalent metal ions on acid recovery were elaborated in detail. Acid dialysis coefficients (UH) values for FeCl2-HCl system were in the range of 0.0194–0.0295 m/h and separation factors were ranged from 27.84 to 52.60 at 25 °C. Furthermore, acid dialysis coefficient (3.28 times) and separation factor (2.84 times) were much greater than commercial membrane DF-120 (UH and S = 0.009 m/h and 18.5), respectively. Moreover, Q-DAN-4 membrane was selected to investigate the effects of multivalent metal ions on diffusion dialysis. The results showed that the presence of different metal salts in hydrochloric acid solution effect the membrane diffusivity and selectivity in diffusion dialysis process due to complexation of metal ions and acid.

High performance anion exchange membrane with proton transport pathways for diffusion dialysis

Abstract High performance anion exchange membranes (AEM) with proton transport pathways were fabricated through cationic functionalization of bromo-methylated poly (phenylene oxide) (BPPO) by a nucleophile dimethylamino pyridine (DMAP). The reaction was selectively occurred at dimethylamino functionalities of DMAP to form quaternary amine groups. The pyridine groups on DMAP having a dibasic nature promoted the formation of proton transport pathways and contributed to hydrophilicity of the membranes. The obtained membranes had the water uptake (WU) in the range of 12–57%, the ion exchange capacity (IEC) from 0.84 to 2.07 mmol g−1, acid dialysis coefficient (UH) from 0.37 to 20.3 (10−3 m h−1) at 25 °C. Interestingly, these membranes exhibited superior separation factor (S) values of 73–351 compared to a commercial DF-120 membrane and most reported membranes in literature. Moreover, the prepared membranes showed excellent thermal, chemical and mechanical stability.

Novel synthetic route to prepare doubly quaternized anion exchange membranes for diffusion dialysis application

Abstract In this work, anion exchange membranes (AEMs) were prepared from double quaternization and sol–gel reaction of synthesized anion exchange precursor and polyvinyl alcohol (PVA). The anion exchange precursor was the result of alkylation reaction of 1,6-Dibromohexane on 1,4-Diazabicyclo[2.2.2]octane (DABCO) and ring opening reaction by 3-glycidoxypropyltrimethoxysilane. The prepared membranes showed good physicochemical properties. The water uptakes were in the range of 82.6–148.5% while the ion exchange capacities (IECs) were in the range of 0.61–0.86 mmol/g. The membranes demonstrated high mechanical strengths and thermal stabilities. Tensile strengths (TS) were in the range of 15.4–22.7 MPa while E b values were in the range of 441.2–541.0%. Those membranes were tested in diffusion dialysis (DD) for recovery of acid by using a simulated waste solution of HCl/FeCl 2 mixture (1 M HCl + 0.25 M FeCl 2 ). The results reveal higher acid dialysis coefficients (U H ) between 30.0 and 44.9 m/h × 10 −3 and separation factor (S) ranges of 20.9–32.3 which are greater than commercial membranes DF-120 (U H = 9 × m/h × 10 −3 and S = 18.5).

BPPO-Based Anion Exchange Membranes for Acid Recovery via Diffusion Dialysis.

To reduce the environmental impact of acids present in various industrial wastes, improved and robust anion exchange membranes (AEMs) are highly desired. Moreover, they should exhibit high retention of salts, fast acid permeation and they should be able to operate with low energy input. In this work, AEMs are prepared using a facile solution-casting from brominated poly-(2,6-dimethyl-1,4-phenylene oxide) (BPPO) and increasing amounts of 2-phenylimidazole (PI). Neither quaternary ammonium salts, nor ionic liquids and silica-containing compounds are involved in the synthesis. The prepared membranes showed an ion exchange capacity of 1.1–1.8 mmol/g, a water uptake of 22%–47%, a linear expansion ratio of 1%–6% and a tensile strength of 0.83–10.20 MPa. These membranes have potential for recovering waste acid via diffusion dialysis, as the acid dialysis coefficient (UH) at room temperature for HCl is in the range of 0.006–0.018 m/h while the separation factor (S) is in the range of 16–28, which are higher than commercial DF-120B membranes (UH = 0.004 m/h, S = 24).