Effect of SiO₂ coating on alumina microfiltration membranes on flux performance in membrane fouling process

Abstract

Inorganic surface modification was performed using a SiO₂ sol–gel technique to mitigate the fouling of alumina microfiltration membranes. A positively charged alumina membrane was coated with SiO₂ to generate a negative charge, and as a result, electrostatic repulsion prevented the serious adsorption (or deposition) of model foulants on the membrane. Upon the formation of the SiO₂ layer, small changes in the surface morphology, pore size, and surface roughness were detected. In particular, as the pore size decreased, the pure water permeability gradually decreased. When the membrane fouling was accelerated with model foulants, the highest normalized flux level and the lowest flux decline ratio (%) were observed in the smallest SiO₂-coated microfiltration membrane (0.1 M SiO₂). In summary, the SiO₂ coating contributed to the optimization of the antifouling properties of the ceramic membranes, although the pore size was reduced.