Effect of reduced graphene oxide/TiO₂ nanocomposite with different molar ratios on the performance of PVDF ultrafiltration membranes

A partially reduced graphene oxide (rGO)/TiO₂ nanocomposite with five different molar ratios (rGO/TiO₂: 3/97, 30/70, 50/50, 70/30 and 90/10) were synthesized and characterized using X-ray diffraction and scanning electron microscopy (SEM) techniques. The polyvinylidene fluoride (PVDF) mixed matrix membranes containing 0.05 wt.% of the nanocomposites were prepared by phase inversion method. The effect of rGO/TiO₂ additive on the morphology and performance of prepared blended membranes was studied by atomic force microscopy (AFM), SEM, energy dispersive X-ray (EDX), FTIR, water contact angle, porosity and permeation measurements, rejection tests and antifouling parameters. The SEM images revealed finger-like structure of the membranes and EDX analysis confirmed well distribution of rGO/TiO₂ nanocomposite in the polymer matrix. The rGO/TiO₂/PVDF membranes showed enhanced hydrophilicity, higher pure water flux and flux recovery ratio compared to the bare PVDF. A comparison of pure water flux of TiO₂ and rGO/TiO₂ containing membranes showed that dispersion of inorganic TiO₂ nanoparticles on the GO surface decreased the aggregation of the nanoparticles and improved the characteristics of the resulted mixed matrix membrane. The blended membrane containing 0.05 wt.% rGO/TiO₂ nanocomposite with GO to TiO₂ ratio of 70/30 showed improved permeability and antifouling performance.