Scaling-resistant anion-exchange membrane prepared by in situ modification with a bifunctional polymer containing quaternary amino groups

Membrane scaling and subsequent cleaning efficiency are major factors limiting commercial applications of electrodialysis. The generation of OH− ions during water splitting at the membrane interface promotes scaling formation. We report a modification of a commercial anion-exchange membrane, which improves its scaling resistance by reducing the water splitting rate. This is achieved by replacing the weakly basic amino groups on the surface of membrane with quaternary ones that do not have catalytic activity with respect to water splitting. We have carried out a comprehensive study of membranes modified by ex situ, and new membranes, for the first time modified in situ, directly inside the electrodialyzer. The in situ modified membranes were found to exhibit better properties in decreasing the water splitting rate, which, in turn, significantly reduces the scale formation on the surface facing the concentration chamber.