Semi-interpenetrating Polymer-Network Anion Exchange Membrane Based on Quaternized Polyepichlorohydrin and Polyvinyl Alcohol for Acid Recovery by Diffusion Dialysis

In this paper, polyepichlorohydrin (PECH) quaternized with N-methylimidazole (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 1H 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 (WR), tensile strength (TS), linear expansion rate (LER), and elongation at break (Eb) of each membrane were characterized. In DD application tests, acid dialysis coefficients (UH+) 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 UH+ and S values than commercial membrane DF-120 (UH+ 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.