Constructing robust and anti-fouling superwettable membrane with layer-by-layer assembly of Fe(OH)3 colloid

Layer-by-layer (LBL) assembly method, with the advantages of simple operation and strong universality, has attracted much attention recently. However, the weak molecule-to-molecule and molecule-to-ion interactions have limited its development. During this work, the molecule-to-solid interaction was adopted and a robust LBL coating was achieved by alternately depositing positively charged Fe(OH) 3 colloids and negatively charged sodium alginate molecules. The molecule-to-solid interaction could continuously regenerate under corrosive conditions due to water insolubility and the chemical stability of solids. When the electrostatic interaction was broken, the abundant chemically stable solids acted as anchors to immobilize the soluble molecules and maintain the stability of the LBL coating. The prepared superwettable membranes exhibited superior oil-in-water emulsion separation efficiency, anti-fouling properties, and chemical stability. Meanwhile, the separation performance survived one week's harsh environments of strong acid and alkali.