Wetting study of PVDF - carbon nanodiscs membranes for water treatment applications via membrane distillation

Since 80’s, membrane distillation has been identified as a promising water treatment process in various wastewater treatments, such as desalination brine, textile, radioactive and oily wastewater.[1] The demand for membranes with stable flux and prolonged lifespan especially in challenging wastewaters containing oils, surfactants etc. has been increased over the last decade.[2] This research is focused on the preparation and evaluation of PVDF membranes containing functionalized carbon nanodiscs (CNDs) [3]. Specifically, carbon nanodics, a new family of nanostructured carbon(s), in order to be compatible with the hydrophobic polymer, were initially functionalized with triphenylphosphonium-functionalized derivatives of 1300 and 5000 Da molecular weight hyperbranched polyethyleneimine (PEI-TPP) and then the obtained hybrid nanomaterials were structurally characterized using various techniques, such as FTIR, Raman, XPS, NMR, SEM, TEM, etc., revealing the successful attachment of PEI-TPPs on the surface of oxCNDs. Subsequently, the CND@PEI-TPP nanoparticles were either incorporated in the matrix or coated on the top of the surface of poly(vinylidene fluoride) (PVDF) porous membranes. The membranes were characterized by SEM, liquid entry pressure (LEP), contact angle, contact angle hysteresis, porosity and surface energy. Their wetting properties against brine wastewater were investigated followed by their evaluation in membrane distillation. Moreover, their fouling behaviour in the presence of various natural organic matter such as humic acid or bovine serum albumin, SDS and octane was determined. It was observed that the modified nanocomposite membranes exhibit improved permeability, salt rejection and antifouling properties compare to the neat PVDF membrane.