Pervaporative performance of polydimethylsiloxane-graphene/polyethersolfune hybrid membrane: Effects of graphene structure and surface properties

Graphene was produced either by chemical reduction of graphene oxide (GO) using hydrazine hydrate (HG)/sodium borohydride (BG) or by straight electrochemically exfoliation of graphite (EG). The X-ray diffraction and Raman spectroscopy confirmed smaller in-plane crystalline sizes for the chemically produced graphenes, and more number of layers and therefore lower structural defects for the EG sample. The graphene samples were used to prepare polydimethylsiloxane (PDMS)-graphene (G)/polyethersulfone (PES) hybrid membranes to investigate their pervaporative performances. All three produced hybrid membranes had better separation performances for removal of phenol from water in terms of phenol flux and selectivity compared to the unfilled membrane (1.3 g/m(2) h and 11.09, respectively). An appropriate interfacial structure for the BG- and HG-filled membranes (having lower number of layers) was achieved at 0.2 wt% graphene content while for the EG-filled membrane, it was attained at 0.4 wt% graphene content. PDMS-BG/PES had the highest phenol flux of 3.6 g/m(2) h due to the lowest carboxylic functional groups and highest C/O ratio of the filler, and PDMS-HG/PES had the best selectivity of 40.02 due to the lowest C/O ratio of the filler and hence the lowest water flux. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.