Influence of carbon-based fillers on photoactive mixed matrix membranes formation

Direct solar membrane distillation is an innovative configuration that uses a photoactive membrane to transform solar light into heat, sensibly reducing temperature polarization effects and feed temperature decrease along the module. This approach has been proved capable of increasing membrane distillation performance and efficiency. In this work, photoactive mixed matrix membranes were prepared by non-solvent induced phase separation procedure using a polyvinylidene fluoride dope solution containing different carbon-based fillers. Commercial graphite and graphene were selected because of their large specific surface area and their influence on the membrane structure and photothermal properties was compared to the results obtained using carbon black. The introduction of the filler allowed to obtain temperatures as high as 60 ◦C on the dry membrane surface when exposed to a simulated sunlight source. Both graphene and graphite had minor effect on the membrane morphology while carbon black increased the mean pore size of the membrane. The direct solar membrane distillation tests, performed using both pure water or a 90 g/L NaCl solution as feed, showed promising improvements (up to 70%) of the distillation flux under light irradiation