Membrane Distillation (MD) is a hybrid thermal/membrane technology emerging either as a promising alternative or as a complement to Reverse Osmosis, having the potential to concentrate saline solutions even up to supersaturation. Presently, performance of conventional MD systems is drastically affected by temperature polarization, a phenomenon intrinsically connected to the removal of latent heat due to evaporation, which causes the decrease of feed temperature at the membrane surface with respect to the bulk. As a consequence, the net driving force to mass transfer falls down along with the thermal efficiency of the process. Due to these adverse effects, technological applications of MD are still elusive. In this work, we prove that thermoplasmonic effect induced by photothermal excitations of silver nanoparticles (Ag NPs), incorporated into polyvinylidene (PVDF) membranes, remarkably increase the feed temperature at the membrane surface exposed to light radiation, thus achieving unmatched performance in a vacuum MD unit.
1 Jan 2017