Modified ultrafiltration membranes for humic acid removal

Polyethersulfone (PES) ultrafiltration membranes were prepared via phase inversion induced by immersion precipitation with a blending method in different concentrations of two hydrophilic monomers, namely 3,5-diaminobenzoic acid (DBA) and gallic acid (GA). Herein we report the effects of these two monomers as additives in the casting solution on the morphology, performance, and antifouling properties of the membranes. The membranes were characterized in terms of pure water flux permeation, humic acid (HA) separation, membrane structure, and morphology. Experimental results show that the different component ratios of each monomer affected the structural property of blended membranes and surface roughness. The equilibrium water content (EWC) and water contact angle were measured to evaluate the change of hydrophilicity of the modified membranes. Trends exhibited that those two additives increased the hydrophilicity of the membranes because of their strong hydrophilic groups. The HA removal by the PES membrane increased considerably with the addition of DBA and GA in the casting solution. Moreover, the membranes prepared by adding DBA and GA in the PES casting solution exhibited better antifouling properties.