Performance of octadecylamine-functionalized graphene oxide nanosheets in polydimethylsiloxane mixed matrix membranes for removal of toluene from water by pervaporation

Functionalized and reduced graphene oxide nanosheets with octadecylamine (rGOODA) were incorporated in polydimethylsiloxane (PDMS) membranes to be used in pervaporation for removal of toluene from water. The properties of the functionalized nanosheets were characterized by FTIR, XRD, Raman, SEM, and TGA analyses. The prepared mixed matrix membranes (MMMs) were characterized using contact angle, AFM, SEM-EDX, TGA, solvent uptake tests. The membranes contained reduced graphene oxide (rGO) represented 111% increment in the enrichment factor compared to that of the bare-PDMS owing to Π-Π interaction of graphene nanosheets and the toluene's aromatic ring as well as high aspect ratio of rGO that causes more tortuous pathways for water permeation. By incorporating rGOODA in the MMMs, the separation factor was increased about 164% rather than that of rGO-contained membrane, which could be mainly attributed to closer Hansen solubility parameter of the functionalized nanosheets to that of toluene, water repelling of the membrane due to more hydrophobicity and steric hindrance of the functionalized nanosheets, their well dispersion which causes more compatibility with the polymeric matrix. The pervaporative performance of membranes with different filler contents were investigated as a function of operational temperatures and feed concentrations. The prepared MMM with 0.4 wt% rGOODA presented the best performance at 30 °C and 150 ppm toluene concentration.