Solar-driven water purification for sustainable clean water supply

Water scarcity has been a severe threat to our society. Indonesia is a tropical country where solar energy is abundant and sustainable because it is available the entire year. In this work, we proposed a bilayer solar steam generation (SSG) system derived from coir fiber biomass as freshwater production from sea water. The proposed bilayer SSG system consisted of cellulose aerogel derived from coir fiber as the support for black ink that serves as photothermal material to convert sunlight into heat to evaporate water. The cellulose aerogel was synthesized from coir fiber using an aqueous urea-ammonia system of the mechanically and chemically pretreated coir fibers. The cellulose aerogel had excellent capillary effect for water with a water rise of approximately 0.63 cm/min. In addition, it also had low thermal conductivity, about 0.41 W/m·K. The water evaporation rate of the SSG system using the cellulose aerogel was relatively high that reached approximately 1.1 L/m2·h under 1 sun irradiation. It appears that cellulose aerogel with excellent capillary effect and low thermal conductivity can function well as both a water transporter and an insulator. The carbon black and cellulose aerogel appear promising as a sustainable photothermal, and substrate material used for solar-driven water purification to supply clean water from seawater.