T-shape solar evaporator constructed with natural wood and Ti2O3 nanoparticles for water evaporation and desalination

Abstract

Desalination by solar-driven interfacial evaporation is considered as an effective green way to solve the shortage of fresh water resources. However, traditional interfacial evaporation systems are subject to heat loss. In this work, we designed and constructed a T-shape solar evaporator by using natural wood as a support and black Ti2O3 nanoparticles (NPs) with a narrow band-gap as a photothermal conversion material. As a T-shape support, natural wood with good hydrophilicity, well-arranged hierarchical channels and low thermal conductivity not only hinders the loss of conducted heat to water, but also ensures a high rate of moisture transport. As the top solar energy absorption layer for thermal localization and salt collection, horizontal wood surface coated by Ti2O3 NPs has a total solar absorption capacity of 93.6% over the full spectrum. A colorless acid-catalyzed silica sol (ACSS) as a binder is introduced in order to improve the adhesion of Ti2O3 NPs on the wood surface. The horizontal wood is connected vertically with another piece of wood for transporting water and providing thermal insulation. The constructed T-shape evaporator achieves a water evaporation rate of 2.33 kg/m2/h for pure water under 1 sun irradiation. In a desalination experiment, the water evaporation rate is 0.31 kg/m2/h and the salt recovery rate is stable up to 50 h at 31.13 g/m2/h. This work may provide new insights into the design and construction of low-cost, environmentally friendly and efficient solar evaporators for seawater desalination.