Graphene-based membranes for water purification processes

Graphene, a single sheet of carbon atoms, has a key role for the manufacture of innovative membranes for water purification and desalination. The aim of this work is to show the vast potential of monolayer graphene and its multi-layer declinations (BLG bilayer graphene, TLG trilayer graphene) in wastewater treatment. The intrinsic defects, present in the graphene layer due to its growth, and the extrinsic defects, induced by the transfer process on porous polycarbonate membranes (PCTE), form leakage pathways that can be successfully used in the rejection of NaCl for desalination applications or for the removal of different pollutant molecules in aqueous solutions. In this particular case, the rejection to salt and to drug molecules (Diclofenac) was studied, and the results reported were obtained in a side-by-side apparatus. Theoretical studies of molecular dynamics have shown that nanoporous graphene with subnanometric pores allows ultra-fast water permeability, due to its atomic thickness, and high salt rejection, due to a strict pore-size control. This work is supposed to be a feasibility study towards the application of single or multi-layer graphene membranes, and consists in an initial characterization of graphene coated membranes, to be then destined to the subsequent steps of creation and control of the aforementioned subnanometric pores.