Evaporator fabricated with accessible photothermal material derived from waste fallen leaves for highly efficient desalination

Abstract

Direct solar steam generation (DSSG) has been considered to be one of the most promising technologies to alleviate the significant threat of freshwater scarcity worldwide. Among these, the solar-thermal evaporator based on carbonized natural materials is a very promising and environmentally friendly alternative. However, due to the high energy consumption and expensive equipment requirements in the preparation of conventional carbon-based materials, developing simple and low-cost material preparation methods without additional energy input is still challenging. Fallen leave is a widely distributed and renewable waste biomass that is easily accessible, which can be made into evaporators for desalination. Herein, the biomass waste fallen leaves were selected as raw material to synthesize carbonized fallen leaves (CFL) by simple sulfuric acid carbonization without energy input. Then the CFL were sprayed onto artificial deerskin towels (ADT), and finally, the portable CFL@ADT evaporators were constructed. Our CFL@ADT evaporator with 1 wing shows a solar absorptance of 97.4 % and an evaporation rate of 1.50 kg m−2h−1 in water with an evaporation efficiency of up to 95 %. The CFL@ADT evaporators provide an attractive alternative to conducting biomass waste resource utilization as well as achieving efficient and economical desalination during the day and self-cleaning at night.