Grafting polyacrylic acid brushes onto zirconia membranes: Fouling reduction and easy-cleaning properties

Highly protein-resistant and easily cleaned ceramic membranes were prepared by grafting PAA brushes onto ZrO₂ membranes via chemical graft polymerization. The pure water flux decreased with increases in the thickness of PAA coating on the ZrO₂ membrane surface. The water flux of the PAA-g-ZrO₂ membranes was highly dependent on the solution pH, and increased at lower solution pH. In addition, the initial flux when filtering a bovine serum albumin (BSA) solution using the PAA-grafted membranes was higher than the pure water flux. The antifouling performance of the PAA-g-ZrO ₂ membranes was assessed via the filtration of a BSA solution. All of the PAA-g-ZrO₂ membranes showed a higher initial rejection and a lower reduction in flux for the BSA solution compared with ZrO₂ membranes. The fouled BSA could be easily eluted from the PAA-g-ZrO₂ membrane surface using cleaning with pure water, and the flux recovery was approximately 70% (the flux recovery of the ZrO₂ membrane was only 17% or so). The densely packed brush-shaped structure of the PAA chains was considered to be responsible for reducing the protein adsorption on the membrane surface.