Hydrogel-coated sponge evaporator for high-efficiency desalination applications

Abstract Solar-driven interfacial evaporation is an effective and achievable way to purify water. In this paper, lignocellulosic sponge (LS), an all-natural, clean, and renewable product, is used as a porous substrate. Carbon black (CB), which has excellent photothermal conversion capability, was used as a gel material by using a simple “impregnation” method with bio-friendly polyvinyl alcohol (PVA) and tannic acid (TA), and a gel coating was generated in situ on top of the lignocellulosic sponge by hydrogen bond cross-linking regulated by water-ethanol solution to obtain a simple and effective photothermal conversion evaporator. The prepared PTLS-CB/Fe 3+ evaporator showed good light absorption with an evaporation rate of 1.93 kg m −2 h −1 in pure water and an evaporation efficiency of 84.57%. The solar evaporator prepared in this paper has the advantages of a simple preparation method and is environmentally friendly. This provides a new approach to the preparation of solar interfacial evaporators.