In Situ Oxidative, Catalytic Oxidative, and Nonoxidative Electrocleaning of Fouled Conductive Membranes

Abstract

Electroconductive membrane (ECM) is a major advancement in the field of membrane technology, which has the potential for fouling mitigation due to its various action mechanisms. However, electrocleaning of a laser-induced graphene (LIG)-based ECM has not been investigated for its potential fouling mitigation; furthermore, nonoxidative electrocleaning has not been explored for any ECMs. In this study, the use of a LIG-based ECM for fouling inhibition and cleaning of fouled ECMs was investigated via oxidative, catalytic oxidative, and nonoxidative electrocleaning for low levels of fouling and severe fouling, as low fouled membranes were easily cleaned. Crossflow water washing and backwashing showed only ∼5−10% flux recovery, while oxidative electrocleaning showed ∼60−80% flux recovery. On the other hand, in situ catalytic oxidative and nonoxidative electrocleaning showed ∼90−100% flux recovery. Oxidative and catalytic oxidative electrocleaning can cause damage to the LIG-based ECMs/filters under anodic potential. On the contrary, nonoxidative electrocleaning was found to extend the life of the ECMs/filters due to inhibition of the electrochemical oxidation and self-oxidation of the ECMs/filters. For severe fouling, oxidative and nonoxidative methods showed limited flux recovery, while catalytic oxidative electrocleaning showed ∼100% flux recovery. The study shows the advantage of nonoxidative electrocleaning for low fouling, while catalytic oxidative electrocleaning can address severe fouling with only 1−5 min of operation.