A novel preparation method for protective coating on hydrophobic membrane based on vapor opposite transmission process

The protective coatings prepared by depositing polymer can effectively retard the fouling and wetting of hydrophobic membranes. However, the existing deposition methods have a certain limitation and the prepared protective coatings are either thick or obviously defective. It is difficult to prepare coatings with an enhanced protective effect on hydrophobic membranes without great adverse effect on membrane flux. Herein, we proposed a novel method to in-situ prepare protective coatings on hydrophobic membranes based on the vapor opposite transmission process. In this process, polyvinyl alcohol (PVA) reacted with glutaraldehyde (GA) only at the opening of the membrane pore channels, thus resulting in the formation of discontinuous coating. Compared with that prepared by the conventional method, the coating prepared by the vapor opposite transmission reaction method was more integral and could be more firmly attach on the hydrophobic membrane. Moreover, the as-prepared coating exhibited a thin thickness and high porosity due to the self-limiting effect in reaction process and mild preparation conditions. Therefore, the coatings prepared by the vapor opposite transmission reaction method exhibited less mass transfer resistance as well as an enhanced protective effect on hydrophobic membranes.