Using soil as photoabsorber for solar steam generation

Continuous solar steam generation requires a photoabsorber with high capillarity or a hydrophilic surface, the capability of floating on water and low thermal conductivity. Hence, we propose an alternative interfacial solar steam substrate made of soil as a novel cost-effective photoabsorber. For this purpose, three soil types, sand (0.05-2 mm), silt (0.002-0.05 mm) and clay (less than 0.002 mm), were used and floated using a polystyrene foam to reduce heat losses. Our results reveal that a maximum evaporative efficiency of 80.01 +/- 3.1% at 1 kW m(-2) was achieved for the silt sample, whereas the corresponding value for water alone was 23.22 +/- 1.4%. In a desalination test, the quality of obtained water from the process greatly exceeds the World Health Organization's drinking water standards. The hydrophilic properties of silt prevent the deposition of impurities on its surfaces, ensuring high durability.