Effects of graphene derivatives on polyvinylidene fluoride membrane modification evaluated with XDLVO theory and quartz crystal microbalance with dissipation.

ABSTRACT

In this study, the different graphene derivatives, graphene oxide (GO), carboxylic acid-modified graphene (G-COOH), and amine-modified graphene (G-NH2 ), were used to prepare polyvinylidene fluoride (PVDF) composite membranes. The membrane modification performance was evaluated using the extended Derjaguin-Landau-Verwey-Overbeek theory and quartz crystal microbalance dissipation monitoring. The results show that the addition of low-dose GO and G-NH2 can improve membrane surface porosity and permeability. The hydrophilicity and electron donor monopolarity of PVDF/GO composite membranes were enhanced by adding more than 0.024 wt% GO, thus improving its antifouling ability. In addition, the enhancement of hydrophilicity, free energy of cohesion, and antifouling ability of composite membrane modified with G-COOH and G-NH2 was more significant compared with that of GO with the same dosage, which implies the important role of functional group in additives. This study provides new insights for the blending modification of PVDF membranes by systematically comparing the addition of graphene derivatives with different functional groups. PRACTITIONER POINTS The comprehensive comparison of membrane modification with different graphene derivatives was investigated. The enhancement of hydrophilicity and antifouling ability of membranes modified with G-COOH and G-NH2 was more significant than that of GO. The free energy of cohesion of nanocomposite membrane was affected by the functional group of additives. G-NH2 composite membrane had the best comprehensive performance with great hydrophilicity, permeability, and antifouling performance.