PVA/SiO2 anion exchange hybrid membranes from multisilicon copolymers with two types of molecular weights

• Published in: Journal of membrane science 2012-05, Vol.399-400, p.16-27
• Main Authors: Wu, Yonghui, Luo, Jingyi, Yao, Lulu, Wu, Cuiming, Mao, Fulin, Xu, Tongwen
• Format: Article
• Language: English
• Subjects: acetic acid; anion exchange; Anion exchange membrane; artificial membranes; Chemistry; Colloidal state and disperse state; composite polymers; crosslinking; dialysis; Diffusion dialysis; Exact sciences and technology; gelation; gels; General and physical chemistry; Hybrid membrane; hydrochloric acid; Membranes; molecular weight; Multisilicon copolymer; polyvinyl alcohol; silicon; solvents; thermal stability
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2012.01.019

► Multisilicon copolymers, with two types of molecular weights, are developed. ► Copolymer with the high molecular weight (Mn of 4152) has two gelation times. ► Membranes can be potentially applied in recovery of CH3COOH (0.009m/h). ► Membranes can be potentially applied in recovery of HCl (0.024–0.043m/h, 28–39). Multisilicon copolymer has a long main chain and many branched chains, with plenty of ion-exchange (N+(CH3)3Cl−) and Si(OCH3)3 groups. Multisilicon copolymer with the low molecular weight (Mr of 795) is difficult to gel, while that with the high molecular weight (Mr of 4152) has two gelation times. One is the “pseudo gelation” within 0.03–2.5 days, and the other is within 14–48 days. The two types of multisilicon copolymers are crosslinked with polyvinyl alcohol (PVA) to prepare anion exchange hybrid membranes. Membranes from the low molecular weight copolymer have lower water uptakes (WR, 62–87%), ion exchange capacities (IECs, 0.6–0.9mmol/g), thermal stability (223–239°C) and mechanical strength (7–12MPa, 42–97%). Membranes from the high molecular weight copolymer are homogeneous, transparent and colourless. They have higher WR of 195–464%, IECs of 1.0–1.5mmol/g, short-term thermal stability of 244–247°C, mechanical strength (15–23MPa, 122–208%) and organic solvent resistance. All the membranes can be potentially applied in diffusion dialysis (DD) process for recovery of CH3COOH and HCl. The dialysis coefficients of CH3COOH (UCH3COOH) can reach up to 0.009m/h, and the dialysis coefficients of HCl (UH) are in the range of 0.01–0.043m/h with the separation factors of 22–39 (0.01–0.029m/h and 28–39 for the low molecular weight, and 0.024–0.043m/h and 22–26 for the high molecular weight), superior to those of commercial DF-120 membrane (0.009m/h, 18.5).