Anion exchange hybrid membranes from PVA and multi-alkoxy silicon copolymer tailored for diffusion dialysis process

Anion exchange hybrid membranes have been prepared from quaternization and sol–gel reaction of multi-alkoxy silicon copolymer (poly(vinylbenzyl chloride-γ-methacryloxypropyl trimethoxy silane) (poly(VBC-co-γ-MPS)) in presence of poly(vinyl alcohol) (PVA). The membranes are of high thermal stability, mechanical strength, and swelling resistance. Thermal degradation temperatures (Td, defined as the temperature at 5% weight loss) are in the range of 263–283 °C. Tensile strength (TS) ranges from 24.5 MPa to 59.2 MPa and elongation at break (Eb) is in the range of 25.4–101.2%. The membranes can remain integrity in 65 °C hot water for more than 25 days and the swelling behavior is better suppressed as poly(VBC-co-γ-MPS) content increases. The membranes are tested for diffusion dialysis (DD) recovery of hydrochloric acid (HCl) from the mixture of HCl and ferrous chloride (FeCl2). The temperature for DD process ranged from 20 °C to 60 °C, revealing that the separation factor (S) values are in the range of 12.1–35.7, comparable to the values of commercial DF-120 membranes. When the temperature increases from 20 °C to 30 °C, the separation performances are increased. Further increase of temperature increases the dialysis coefficients, but decreases the S value. The membrane structure and properties are correlated with the DD performances.