Application of sulfonic acid group functionalized graphene oxide to improve hydrophilicity, permeability, and antifouling of PVDF nanocomposite ultrafiltration membranes

A novel, highly hydrophilic nanocomposite additive, sulfonated graphene oxide (SGO), was synthesized from graphene oxides (GO), and characterized using a range of techniques. To examine the effects of the sulfonic acid groups of the filler particles on the polyvinylidene fluoride (PVDF) membrane performance, the PVDF-GO/SGO modified membranes were obtained through phase inversion by dispersing GO and different concentrations of SGO (0.4-1.2 wt%). The surface of the prepared membranes was analyzed by scanning electron microscopy and atomic force microscopy. The addition of GO and SGO caused by an increase in surface roughness, porosity, and pore size of the membranes compared to the PVDF membrane. The P-SGO and P-GO blend membranes showed a 146.6% and 53.3% enhancement of the water permeation flux, respectively. The presence of additional sulfonic groups (-SO3H) on SGO supports hold a thicker water hydrogen layer and improve the water flux. The anchored -SO3H group in SGO is a stronger hydrogen-bonding group compared to the -COOH/-OH groups present in GO. From the antifouling test, P-SGO with the 0.8 wt% blend membranes exhibited a high water flux recovery ratio (FRR) of 88.7% and low irreversible fouling (R-ir) Of 11.2% compared to the GO nanocomposite membrane (75% and 24%, respectively). This was recognized to the high hydrogen bonding forces and electrostatic repulsion of SGO against the fouling proteins. Overall, the induced SGO nanoparticle opens a novel path to enhance the hydrophilicity, water flux, antifouling, and mechanical performance of PVDF ultrafiltration membranes.