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A branched polymer was prepared by grafting allyltrimethylammonium chloride onto polyvinyl alcohol (PVA) via free‐radical polymerization. Afterwards, a series of hybrid membranes were prepared by sol‐gel cross‐linking between quaternary ammonium‐PVA and tetraethoxysilane. The obtained membranes were characterized in terms of infrared spectroscopy, ion exchange capacity, water uptake, linear expansion ratio, and acid resistance. The thermal properties of the membranes were investigated as well. The diffusion dialysis performances of the membranes were tested by using a simulated feed solution containing HCl and FeCl2. The diffusion dialysis coefficients and the separation factors were much better than those of the commercial DF‐120 membrane. [ABSTRACT FROM AUTHOR]

Anion exchange membranes (AEMs) based on new ion exchanging groups were successfully prepared by functionalization of brominated poly(2,6-dimethyl-1,4-phenylene oxide) with 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU). High anion permeability was observed due to good self-dissociation ability of anion exchanging groups-anion ion pairs attributing to high basicity of DBU. When used in diffusion dialysis (DD) for acid recovery from a simulated iron polishing waste solution (HCl, 1.27 mol/L; FeCl 2 , 0.20 mol/L), the as-prepared membranes exhibit extraordinary proton diffusion coefficient ( U ) of 0.027 m/h and high separation factor of 62.6 at 30 °C, implying the synthesized AEM is a prospective candidate to be applied in the field of acid recovery. [ABSTRACT FROM AUTHOR]

To improve the efficiency of acid recovery by diffusion dialysis, novel anion exchange membranes (AEMs) have been fabricated from quaternized poly(2,6-dimethyl-1,4-phenylene oxide)/Silicon dioxide hybrid material (QPPO–SiO 2 ) by electrospinning and post-treatment (solvent fumigation and hot-press). While being used in a simulated iron polishing waste solution containing 1 mol/L HCl, and 0.225 mol/L FeCl 2 , the membrane exhibits both higher acid permeability ( U H , 0.053 m/h) and selectivity ( S , 68.05) in comparison with the direct casting QPPO–SiO 2 hybrid membrane, of which possess relatively lower values of U H (0.041 m/h) and S (49.45). Besides, compared with commercial DF-120 membrane ( U H =0.005–0.009 m/h, and S =18.5–23.5), hot-pressed electrospun QPPO–SiO 2 membrane shows more than approx.7 times higher U H and approx.3 times higher S values underling its advantage in DD application. [ABSTRACT FROM AUTHOR]

Semi-interpenetrating polymer networks (sIPN) based on anion exchange membranes (AEMs) for acid recovery process were fabricated by immobilizing polyvinyl chloride (PVC) in dimethylaminoethyl methacrylate (DMAM) and divinylbenzene (DVB) copolymer (P(DMAM-co-DVB)). Prepared membranes were fully characterized in terms of FTIR, TGA, ion exchange capacity (IEC), water uptake ( W R ), etc. Membrane structure and performance can be tuned by varying the content of PVC and dosage of cross-linking agent as well. Consequence of PVC content plus the cross-linking degree on ion permeability and selectivity was discussed in brief. Results revealed that the prepared membranes possess excellent thermal and acid stability due to the incorporation of chemically stable PVC matrix and the formation of sIPN morphology. Acid dialysis coefficients ( U H ) appeared in the range of 0.012–0.040 m/h and separation factors ( S ) ranged from 36 to 61 at 25 °C. These obtained values are much higher than that of commercial membrane DF-120 (0.009 m/h for U H , 18.5 for S ). This methodology can be effortlessly scaled up and the obtained membranes could be an encouraging candidate for the acid recovery process via diffusion dialysis. [ABSTRACT FROM AUTHOR]

Rapid development of diffusion dialysis based on anion exchange membranes (AEMs) established its prominent significance as a leading candidate in the field of separation science and technology. AEM-based diffusion dialysis (DD) processes intended to acid recovery have generated much interest due to their exclusive selectivity. Here, we report the effects of novel Poly(DMAEM-co-γ-MPS)-based AEMs for DD applications (acid recovery). Free radical polymerization was successfully done with the initiator azobisisobutyronitrile (AIBN) to achieve the desired polymer Poly(DMAEM-co-γ-MPS). Finally, quaternization with EPTAC and methyl iodide was done to make the membrane matrix charged. The dosage of Poly(DMAEM-co-γ-MPS) inside membrane matrix plays a crucial role to determine the physiochemical and electrochemical properties of the prepared membranes. The influence of Poly(DMAEM-co-γ-MPS) on the acid recovery behavior of the membranes was explored in detail. The prepared membranes displayed high thermo-mechanical stability. At 25 °C, the acid dialysis coefficient (U H ) values were between 0.016–0.029 m/h, while the separation factors (S) ranged from 23.3 to 87.7. Both the acid recovery (7.25 times) and separation factors (~3.6 times) are much higher than the commercial fiber supported anion exchange membrane DF-120B (U H and S=0.004 m/h and 24.3, respectively). Prepared AEMs are the potent candidate for acid recovery via diffusion dialysis. The highlight of this work is the fabrication of new AEMs, which shows high acid dialysis performance and selectivity. [ABSTRACT FROM AUTHOR]

The development of polymeric anion exchange membranes (AEMs) for recycling acid is facing a serious difficulty, the desired acid passage and undesired salt leakage dilemma. Ionic domains are the only channels to conduct H + ions and metallic ions, and thus viable modifications on ionic domains render the permeation of two ions simultaneously enhanced or limited, leading to “trade-off” effect. Herein, we propose an origin strategy of “three-phase” AEMs to beat this “rade-off” effect. Apart from typical hydrophobic polymer backbone and hydrophilic cation phase domains, the auxiliary phase domains built by graphene oxide (GO) sheets were added. Due to the abundant oxygen containing groups distributing on GO, the auxiliary phase domains not only aid to transport H + ions, but also capture metallic ions. With only 0.5 wt% GO loadings, the “three-phase” AEM increased acid recovery efficiency and separation factor by 40% and 51% for the FeCl 2 /HCl system respectively, compared with the “two-phase” AEM. To explain these results, density functional theory (DFT) simulation was applied to study the interactions between GO and Fe 2+ ions. [ABSTRACT FROM AUTHOR]

• In-situ crosslinked AEMs with self-assembled nanostructure were prepared. • The membranes exhibited excellent H+ diffusion coefficient and selectivity. • Balance between the acid recovery efficiency and processing capacity was achieved. The highly selective anion exchange membranes (AEMs) for acid recovery were invented via cationic functionalization of bromo poly(2, 6-dimethyl-1, 4 phenylene oxide). The quantity of tris(2-(2-methoxyethoxy) ethyl) amine (TDA) was precisely adjusted to obtain hydrophilic ion transport channels in the membrane structure. The vinyl part of 2-(dimethylamino) ethyl methacrylate (DMAEMA) was in-situ crosslinked to achieve high selectivity. The cationic groups being efficiently produced by TDA and DMAEMA were responsible for high flux, while the crosslinked nature of the membrane restricted the active transport of Fe2+ ion. The self-assembled nanostructure AEMs showed an excellent selectivity from 49 to 1391 and H+ dialysis coefficients up to 0.0325 m h−1, respectively at 25 °C, which is superior as compared with a commercial DF-120 membrane and some recently reported dense membranes. The representative membranes exhibited better operational stability for 10 consecutive cycles during the entire diffusion dialysis process. [ABSTRACT FROM AUTHOR]