Effect of graphite oxide and multi-walled carbon nanotubes on the microstructure and performance of PVDF membranes

Polyvinylidene fluoride (PVDF)/graphite oxide (GO) and PVDF/multi-walled carbon nanotubes (MWCNTs) ultrafiltration membranes were prepared by solution-blending the ternary mixture of PVDF/carbon materials/dimethylacetamide in combination of the phase inversion method. It was indicated that the blend membranes exhibit better pore structure and higher surface roughness than the pristine ones, and PVDF/GO blend membranes contributed bigger pores but lower surface roughness than PVDF/MWCNTs blend membranes. For PVDF/MWCNTs and PVDF/GO blend membranes, 114% and 74% improvement of pure water permeation flux was achieved, respectively. The hydrophilicity was increased significantly and the bovine serum albumin rejection of PVDF/MWCNTs and PVDF/GO blend membranes was enhanced about 31.8% and 28.7%, respectively, compared with those of the pure PVDF membranes. Hence, it can be expected that graphitic carbon materials open up a new pathway for improving the performance of blend membranes and the ultrafiltration membranes modified by graphitic carbon materials have a promising application prospect.

► GO and MWCNTs show potential to modify PVDF membranes via oxygen-containing groups.
► MWCNTs possess higher specific surface and hence perform better than GO.
► The PVDF blend membranes exhibited higher surface roughness than pristine ones.
► Hydrophilicity and permeability of membranes were increased significantly.