Biomass eggplant-derived photothermal aerogels with Janus wettability for cost-effective seawater desalination

The main challenges in transforming natural-derived biomass materials into a solar steam generator (SSG) are the complicated preparation process and the inevitable pollution in the carbonization process. To address this, we designed a one-pot green immersion preparation process to load nanoparticles with photothermal effect on the natural eggplant aerogel (Fe3+[email protected] aerogel), which can generate steam under the sunlight. The formed 3D sponge-like porous structure with directional 2D water transport channels can achieve rapid water pumping and multiple refraction of the light path in the interior of the prepared aerogel. This lightweight and low thermal conductivity aerogel has an evaporation rate of 1.61 kg m−2 h−1 under 1.0 sun, and shows excellent purification effects on seawater with high salinity, strong acids/alkali and dye solutions. Notably, the skin-core structure (smooth skin-rough core) and Janus wettability (hydrophobic skin-hydrophilic core) of the Fe3+[email protected] aerogel can efficient construct 2D water path to minimize the heat loss during the solar evaporation process and achieve excellent self-desalination during seawater desalination. With the help of life cycle assessment (LCA), the sustainability of different desalination systems was quantified, and it was found that the aerogel has relatively low global warming potential, which helps to promote the environmentally-friendly manufacturing of evaporators with zero liquid discharge. The exploited photothermal evaporator derived from biodegradable biomass eggplant is expected to provide a green and cost-effective strategy in solving global issues of water and energy shortages.