Solar-driven interfacial desalination actively adjusted by the electric field

Abstract

Interfacial evaporation is deemed as an efficient utilization of solar energy for desalination. Notwithstanding, the heat loss and ion transportation are commonly contradictory in evaporator, which means that the balance between heat transfer and mass transfer is fragile. Meanwhile, the electric field regulation method is effective on the microscale transportation of ion in porous solar absorber and reduction of the heat loss. Herein, to eliminate the salt precipitation left on evaporator surface and maintain a superior evaporation efficiency, an electrode structure is coupled on the solar-driven interfacial evaporator, and the evaporation performance and salt-resistant performance in the electric field are studied in the saline water with 0–20 wt% concentrations. Subsequently, the mechanism of electric field on surface tension, electric field force and evaporation enthalpy are discussed. Concretely, the evaporation is increased up to 29.14% by the electric field, and the evaporation efficiency is reinforced from 65% to over 90%. Moreover, the salt precipitation on the evaporator surface is reduced greatly, which improves the self-cleaning capability of evaporator. Besides, the excellent desalination performance of the interfacial evaporator with electric field is resultant of the reduced surface tension, enhanced electric field force, decreased evaporation enthalpy, weakened ion nucleation and crystallization.