Surface hydrophilic modification of PVDF membranes by trace amounts of tannin and polyethyleneimine

A commercial PVDF Microfiltration (MF) membrane was surface modified via a simple coating method for improvement of the hydrophilicity and anti-fouling performance. Herein, trace amounts of tannin acid (TA) and Polyethyleneimine (PEI) were firstly used with (3-Chloropropyl)trimethoxysilan (CTS) to endow the PVDF membranes with hydrophilicity. The physicochemical property of the modified membranes was characterized by SEM, AFM, ATR-FTIR and XPS respectively, and a series of tests including water contact angle (WCA), underwater oil contact angle (OCA), pure water flux (PWF), anti-fouling experiments and so on were utilized to inspect the modified effect. Benefiting from the interactions among CTS, PEI and TA, several coating layers formed on the surface of the membranes and remarkable hydrophilicity with water contact angle of 16 degrees was obtained, moreover, the pure water flux of this composite membranes could reach 10,782 L/m(2).h.