Hydroxyl-functionalized ultra-thin graphitic-carbon-nitrite nanosheets-accommodated polyvinyl alcohol membrane for pervaporation of isopropanol/water mixture

This report describes, for pervaporation dehydration of IPA/water mixtures, different types of g-C3N4 nanosheets accommodated in a polyvinyl alcohol matrix, and coating on an alumina hollow fiber membranes were fabricated. Namely, bulk g-C3N4 (BCN), from the thermal polymerization of a melamine precursor, followed by its exfoliation by acid treatment to prepare acid-treated g-C3N4 (ACN), further hydroxyl functionalization by glycidol treatment to obtain glycidol-modified g-C3N4 (GCN) were synthesized. As-synthesized BCN, ACN, and GCN sheets were characterized using FTIR, XRD, XPS, and AFM techniques. Dispersion of the BCN, ACN and GCN sheets in the PVA matrix was confirmed by FE- SEM, FT-IR, and DSC studies. Owing to the interfacial interaction between the g-C3N4 sheets and PVA, the mechanical strength of the membrane increased; it was more profound for GCN sheets accommodated membrane that attributed to hydrogen bonding interactions due to glycidol modification confirmed. In pervaporation tests, at a fixed content (2 wt.%) for evaluating the modification effect, the best performance was obtained (flux= 0.199 kg/m2h and separation factor 139.8) with the GCN type g-C3N4 sheets accommodation amidst three types of g-C3N4 nanosheet-accommodated membranes delivered at an 80/20 (w/w, (IPA)/water) feed mixture at 40 °C.