Improved stability of self-healing hydrogel pore-filled membranes with ionic cross-links

A self-healing water filtration membrane that can autonomously recover from rejection loss due to physical damage is a promising solution to deal with prevalent membrane integrity deterioration problems. While hydrogel-composite membranes fabricated using poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) hydrogel and a polyethersulfone support exhibit strong self-healing property, the stability of these membranes in high ionic strength solutions is uncertain. This study investigates the effect of changes in the ionic strength of the swelling medium due to the presence of saline and acidic solutions on PAMPS pore-filled membranes. Acidic conditions had a deleterious effect on the pore-filled membranes, resulting in loss of rejection to 50%. However, the presence of cations such as calcium and sodium ions in saline solutions improved the stability and self-healing property of PAMPS pore-filled membranes substantially. Ionically cross-linked membranes showed rejection recovery from values as low as 13%, which is a marked improvement over previous pore-filled membranes which did not show any self-healing property when the rejection fell below 30%. The results of this study suggest that ionic cross-links provide a facile approach to improve the performance of self-healing hydrogel pore-filled membranes.