Porous functional materials with excellent solar-thermal and electro-thermal properties for desalination of saline water

Abstract

Desalination of saline water is a key technology to produce safe drinking water. Here, we report a novel type of reduced graphene oxide (GO) nanosheets modified porous functional materials (rGS) with both excellent solar-thermal and electro-thermal properties for efficient, portable, and continuous desalination of saline water. The rGS porous materials are prepared by modifying porous melamine sponges with GO nanosheets, and then reducing GO nanosheets into reduced GO (rGO) nanosheets. With sufficient rGO nanosheets coated on rGS porous materials, water evaporation fluxes of rGS-5 porous materials are > 1100 g m-2h−1 in solar-thermal desalination under 1000 W m−2 and > 3600 g m-2h−1 in electro-thermal desalination under direct voltage of 20 V due to the excellent solar-thermal property and Joule effect of rGS. The salt rejection values are always higher than 99.95% towards different saline waters including hypersaline water, and the salinities of distilled waters are always far lower than the WHO standard for safe drinking water. The strategy and results in this work provide valuable guidance for designing portable desalination systems to produce safe drinking water by simply using solar energy and/or direct-current power supply in certain applications with special needs such as remote regions and disaster situations.