Novel design of photothermal interfacial distillation device and its application in desalination and pollutants removal

Abstract

The limitations of a single-function solar-driven interfacial evaporation device applied to unpurified water (brine and wastewater) with a complex composition have been exposed. Herein, a solar-driven photothermal evaporation device with the nature of salt-resistance as well as removal of Rh B remaining and oil slicks in bulk water is established through a novel design, with the aim of breaking the current limitations. Concretely, the oil slicks (toluene and cyclohexane) and residual Rh B in bulk water are eliminated by the superhydrophobic part of the device, which makes it possible to protect the device and the environment from the negative effects of oil slicks and the enrichment of dyes. Furthermore, the purification efficiency of the device is above 99.9 % for heavy metal ions and 99.9 % for Rh B solution. Then, the device shows evaporation rates of 2.81 kg·m−2·h−1 (deionized water), 2.77 kg·m−2·h−1 (3.5 wt% NaCl solution), and 2.60 kg·m−2·h−1 (10 wt% NaCl solution) under one sun illumination in different water sources. Meanwhile, the salt-resistance mechanism of the device is the passive transport of salt solution with high concentration between the bulk water and the evaporation surface, which is ascertained through the salt flow being observed in bulk water. A great potential is revealed in the device in desalination and wastewater purification.