Hypochlorite degradation of crosslinked polyamide membranes: I. Changes in chemical/morphological properties

When disinfecting or cleaning agents contact polymer-based membranes, hydrolysis and oxidation with the membrane change surface properties. The research reported here discusses the effect of exposure to solution of hypochloric acid (disinfecting agent) on the chemical and morphological properties of a crosslinked polyamide membrane (LFC1, Hydranautics©). Effects on the membrane were evaluated using AFM, XPS, FT-IR, contact angle, and streaming potential analysis. Chlorine incorporated in the membrane increased with increasing hypochlorite concentration and decreasing pH of a soaking bath. Exposed membranes were more hydrophilic and had a slightly more negative zeta potential. The chlorination broke and weakened hydrogen bonding by decreasing the number of hydrogen bonding sites. This study shows that the use of chlorine chemically changed the surface properties of the crosslinked polyamide LFC1 membrane, but there was no change in roughness and morphology.