A portable high-performance self-insulated solar evaporator based on wooden sponge for seawater desalination and wastewater purification

Abstract

Over 70 % of the earth's surface is water, though people are facing a shortage of clean water. Desalination and purification plants have been utilizing inexhaustible saline and dirty water for decades, but here we present a portable solar-powered device that works during the journey. The independent steam generator is based on a novel wooden material coated with carbonized carbon dots (CCD). A facile hydrothermal treatment is applied to the balsa wood to produce a superhydrophilic, salt-resisting, and self-insulated wooden sponge. The CCD microspheres show broad absorption over the solar spectrum while the wooden sponge provides a rapid water supply and heat localization. The floating CCD@wooden sponge evaporator generates steam at the rate of 2.24 kg m−2 h−1 and has an energy efficiency of 85.0 % under 1 sun irradiation. With a unique design of portable water purifier, a traveler could easily obtain clean water after collecting and purifying undrinkable water such as seawater and wastewater on the move as long as the sun shines.