No abstract

In this paper, polyepichlorohydrin (PECH) quaternized with Nmethylimidazole (ImPECH) was successfully synthesized. ImPECH, polyvinyl alcohol, and tetraethyl orthosilicate were used to prepare anion exchange membranes that possessed a semi-interpenetrating polymer-network structure. These membranes were designed for acid recovery by diffusion dialysis (DD). The successful synthesis of ImPECH was verified via Fourier transform infrared spectroscopy (FTIR) and 1 H NMR spectroscopy. Meanwhile, the prepared anion exchange membranes were characterized by FTIR, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). In addition, the ion exchange capacity (IEC), water uptake (W R ), tensile strength (TS), linear expansion rate (LER), and elongation at break (E b ) of each membrane were characterized. In DD application tests, acid dialysis coefficients (U H + ) of the membranes ranged from 8.56 × 10 −3 m/h to 27.33 × 10 −3 m/h and separation factor (S) values were all above 22.55. These results showed that anion exchange membranes had higher U H + and S values than commercial membrane DF-120 (U H + is 9.00 × 10 −3 m/h and S is 18.00) and other better general properties including the LER, TGA, TS, and so on. The prepared membranes showed a wide application prospective for acid recovery via DD.

In order to improve the performance of the anion exchange membrane (AEM) used in acid recovery from industrial wastewater, this study adopted a new strategy in which brominated poly (2,6-dimethyl-1,4-phenyleneoxide) (BPPO) and polyepichlorohydrin (PECH) were used as the polymer backbone of the prepared membrane. The new anion exchange membrane with a net structure was formed by quaternizing BPPO/PECH with N,N,N,N-tetramethyl-1,6-hexanediamine (TMHD). The application performance and physicochemical property of the membrane were adjusted by changing the content of PECH. The experimental study found that the prepared anion exchange membrane had good mechanical performance, thermostability, acid resistance and an appropriate water absorption and expansion ratio. The acid dialysis coefficient (UH+) of anion exchange membranes with different contents of PECH and BPPO was 0.0173–0.0262 m/h at 25 °C. The separation factors (S) of the anion exchange membranes were 24.6 to 27.0 at 25 °C. Compared with the commercial BPPO membrane (DF-120B), the prepared membrane had higher values of UH+ and S in this paper. In conclusion, this work indicated that the prepared BPPO/PECH anion exchange membrane had the potential for acid recovery using the DD method.

Anion exchange membranes with auxiliary group were prepared by quaternized brominated polyphenylene oxide and hydroxyl tertiary amine. The basic properties of the membrane were characterized using ion exchange capacity, water content, linear expansion rate, thermal weight loss, acid resistance and microstructure of membrane, and so forth. The application of the membrane in the recovery of acid by diffusion dialysis (DD) was also explored showing the excellent comprehensive performance where the dialysis coefficient of HCl (U H+ ) increases from 0.011 to 0.033 m/h, but the separation factor (S) is over 35.6. Comparing with the commercial DF-120 membrane (0.009 m/h, 18.5), the auxiliary hydroxyl with group can improve DD performance of the membrane markedly. Our finding shows the membranes with auxiliary hydroxyl group developed here have great potential for high-efficiency acid recovery by diffusion dialysis.

In this work, a novel silane coupled cationic precursor (SAGS) was synthesized by 3-glycidyloxypropyltrimethoxysilane and sodium 2-((2-aminorthyl)amino) ethanesulfonate. A series of cation exchange membranes were prepared with poly(vinyl alcohol) (PVA) and SAGS by a sol-gel-based process. The structure of the prepared membranes were characterized by Fourier transform infrared spectrum (FTIR) and scanning electron microscopy (SEM), and its properties were studied by water uptake (WR), cation exchange capacity (CEC), linear expansion ratio (LER), alkali stability, thermogravimetric analysis (TGA), mechanical properties, and diffusion dialysis performance. FTIR and X-ray photoelectron spectroscopy (XPS) confirmed the successful preparation of SAGS membranes, and SEM images showed that the prepared membranes were dense and uniform. The WR values of the SAGS membranes were in the range of 91.49–122.39%, and the LER values were 17.65–28.21%. In addition, the SAGS membranes had suitable CEC value, good alkali resistance, and thermal stability which ensured the application of membranes in the field of diffusion dialysis (DD) for alkali recovery. In the DD test, the dialysis coefficients of NaOH (UOH) ranged from 0.012 mm/h to 0.023 mm/h, and the separation factors (S) was in the range of 30.77–16.43. In conclusion, the prepared CEM containing silicon oxygen bonds by PVA and SAGS reaction has the advantages of low price, friendly environment, good alkali resistance, simple preparation process, and great application potential in the textile manufacturing wastewater recovery.