Preparation and properties of substrate PVA-GO composite membrane for solar photothermal conversion

Solar thermal desalination (STD) is a promising and sustainable technology for extracting clean water resources. Whereas recent studies to improve STD performance primarily focus on interfacial solar evaporation, a non-traditional bottom heating method was designed in this study. Herein, we prepared the polyvinyl alcohol/graphene oxide (PVA-GO) composite membrane and adhered to the bottom of a beaker using crystallized PVA. The GO was loaded on a non-woven fabric and different concentrations of PVA were compared for their effect on the evaporation efficiency. The results showed that the addition of PVA increased the evaporation rate. The surface characteristic of GO membrane without PVA was a fibrous filamentous structure as observed by SEM, whereby the fibers were clearly visible. When the PVA concentration reached 6%, the non-woven fiber was completely wrapped by PVA. Under the action of a fixed light intensity, the photothermal conversion rates of GO, 2% PVA-GO, 4% PVA-GO and 6% PVA-GO membrane device could reach 39.93%, 42.61%, 45.10% and 47.00%, respectively, and the evaporation rates were 0.83, 0.88, 0.94 and 0.98 kg·m−2h−1, respectively. In addition, the PVA-GO composite membrane showed an excellent stability, which has significance for industrial application.