Continuous solar desalination based on restricted salt crystallization zone

Abstract

Salt crystallization is a key factor restricting the long-term application of solar desalination. In this study, a new type of solar evaporator with loose lateral channels was successfully prepared to control the salt crystallization phenomenon during solar evaporation process. The evaporation rate and solar evaporation efficiency of the prepared evaporator increased to 1.32 kg/m2 h and 88%, respectively. The evaporation rate was maintained above 1.2 kg/m2 h when the high concentration brine was used for evaporation treatment for a long time, and the salt crystallization zone was limited to the edge of the photothermal layer. The re-dissolved polyethylene glycol (PEG) constructed the smooth lateral channels for salt solution transport in the graphene oxide (GO) photothermal layer, and the concentrated salt solution was more likely to be transported laterally to the edge of GO layer due to the resistance of upward transport during solar evaporation. Because the formation area of crystalline salt was limited to the edge of the photothermal layer, the effective evaporation area of the photothermal layer was maintained, thereby ensuring continuous solar desalination.