Relationship between permeate flux and surface roughness of membranes with similar water contact angle values

In this study, it was evident that poly(vinylidene fluoride) (PVDF) membrane with a smooth surface (B2) displayed normalized flux as well as permeate flux superior to PVDF membrane with a rough surface (B1) during microfiltration. Before carrying out permeate flux and normalized flux tests, two PVDF membranes were prepared in order to obtain similar characteristics such as material, average pore size, and water contact angle value for the purpose of accurate comparisons under similar membrane preparation conditions. In flux performance tests where humic acid (HA) was used as feed solution, the permeate flux of the B2 membrane with the smooth surface was 12.02% higher (15.65 L/m2 h difference at 0.2 bar) than that of the B1 membrane with the rough surface after 120 min. Moreover, the B2 membrane also displayed higher normalized flux compared with the B1 membrane, which was caused by difference in surface structure.