Silver Nanoparticle-Enabled Photothermal Nanofibrous Membrane for Light-Driven Membrane Distillation

We demonstrate a novel, innovative photothermal nanofibrous composite membrane for ultraviolet light-driven membrane distillation (UVMD) in which the photothermal nanoparticles, i.e., silver nanoparticles (Ag NPs), are embedded in a porous membrane to capture light (provided by an ultraviolet LED light) without any other heating methods, completing the photothermal transformation at the interface between the surface of the membrane and the water, providing a high-efficiency (53 ± 7%) heating method for the MD process. Here, Ag NPs were incorporated into the hydrophobic polyvinylidene fluoride (PVDF) nanofibrous membranes by an electrospinning technique. The photothermal heating effect on the desalination capability of the PVDF-Ag nanofibrous membrane was investigated by a UVMD module coupled with a 50 W, 400 nm LED light irradiation source. During the 60 h UVMD test period (3.5 wt % NaCl salt feed), membranes with 20 wt % Ag NPs (with respect to PVDF polymer) presented a flux of 2.5 kg/(m 2 ·h) and low permeate conductivity (2.65 μs/cm) with no pore wetting detected. These results indicate that UVMD has prospective application for desalination with the help of novel photothermal nanofibrous membranes through efficient utilization of renewable energy, such as solar energy.