Silver nanoparticles-lignin charcoal/polyvinyl alcohol sponge with enhanced photothermal evaporation properties

Water purification by using solar-driven photothermal evaporation materials is a green technology with potential application in water purification. In this paper, silver nanoparticles loaded lignin charcoal (AgNPs@LC) are firstly obtained by high-temperature reduction of sodium lignosulfonate impregnated with silver nitrate solution. Then the polyvinyl alcohol (PVA) sponges doped with AgNPs@LC are obtained by mechanical foaming and chemical cross-linking method. Here, incorporation of AgNPs@LC enhances the evaporation rate of the sponge, and the optimal evaporation rate of AgNPs@LC/PVA is 1.52 kg m-2 h- 1 under 1 solar irradiation, and the photothermal conversion efficiency is about 94.7 %. In addition, simulated desalination experiment yields an average efficiency of 87.2 %. Therefore, this study provides a low-cost, easy-to-prepare PVA sponge with good evaporation performance, which has promising application in the field of solar-driven water evaporation.