Impact of graphitic carbon nitride nanosheets in mixed- matrix membranes for removal of heavy metals from water

Abstract

Removal of heavy metal ions from water is being a challenge and Polysulfone (PSf) membranes have shown great potential to remove them from contaminated solutions. In this work, the introduction of Graphitic carbon nitride nanosheets (g-C3N4) into PSf membranes was implemented to improve the permeability and separation performance of PSf membranes. g-C3N4 was incorporated into the membrane matrix via nonsolvent induced phase inversion method. The prepared mixed matrix membranes showed enhanced performances towards water filtration. The incorporation of g-C3N4 into the membrane matrix caused an increase in the desired physicochemical properties like hydrophilicity and surface charge density. This in turn enhanced the rejection of heavy metal ions. The presence of free –NH2 groups on the surface of the membrane helps in increasing the water permeability of the mixed matrix membranes. At 1 bar pressure, the mixed matrix membranes showed rejections higher than 95, 80, and 70 % for lead, cadmium, and arsenic, respectively. Anti-fouling properties of PSf membrane were also enhanced by g-C3N4, which was due to a notable increase in hydrophilicity and the formation of hydration layer on the membrane, preventing interactions between membrane surface and Bovine Serum Albumin (BSA). These properties could be favourable in fulfilling the need of a potential candidate for filtration of waters contaminated by toxic ions.