Antifouling graphene oxide-polyvinylidene fluoride mixed matrix membrane for membranes distillation applications

Porous hydrophobic mixed matrix membranes with antifouling properties were produced by synergic combination of graphene oxide (GO) with polyvinylidene fluoride (PVDF). The protocol developed was easily scalable and environmentally friendly. This last property was guaranteed by the use of a not-toxic solvent (dimethyl sulfoxide) to solubilize the polymer and properly disperse the GO, a green non-solvent (water) to induce phase separation and the absence of any pore forming additive in the casting solution. The presence of the 2D-nanofiller in the casting solution influenced surface charge but also the structure of the formed membranes inducing the formation of crystallites (prevalently in the ?-form) with larger dimensions with respect to the polymeric PVDF prepared without GO. Membrane fouling caused severe declining of flux in PVDF membrane in direct contact membrane distillation (DCMD), as a result of the relevant deposition of humic acids on the hydrophobic surface of the membrane. On the contrary, mixed matrix PVDF-GO was less prone to fouling, as confirmed by surface characterization techniques and stable performance in DCMD before and after prolonged contact with humic acids.