Rational design of high-efficiency interfacial solar evaporator with low evaporation enthalpy based on biomass-derived materials and silica aerogel

Abstract

The proper design of evaporator structures and the selection of effective solar absorbers are the main methods for increasing the evaporation rate. In this study, we have selected carbonized natural wood (CNW) as a support for water transportation, a SiC and carbon composite (SCC) as an absorber from wood and rice husks by high-temperature annealing, and a thermal insulation layer of silica aerogel (SA) from water glass by freeze drying. All components were assembled in a trilayered solar evaporator, denoted as CAS. Owing to the abundant hydrophilic groups, superwettability, and vertical channels of CNW, ultralow thermal conductivity and porous structure of SA, and excellent light absorption and solar heat conversion of SCC, the trilayered CAS has a low evaporation enthalpy of 0.8118 MJ kg⁻¹ and demonstrates a high evaporation rate (4.21 kg m^-2h⁻¹), an excellent evaporation efficiency of 94.94 %, good salt resistance, and long-term stability. In addition, CAS can be used to purify water from various contaminants with excellent performance. This study provides a sustainable method for preparing cost-effective evaporator components from biomass or cheap sources for solar evaporation, which is conducive to solving the global energy crisis, freshwater shortage issues, and the elimination of biomass waste.