An anti-oil-fouling superhydrophilic composite aerogel for solar saline alkali water desalination

Abstract

Solar evaporation generation is a promising method for purifying high salinity water using renewable solar energy. However, the design for the efficient antifouling solar-thermal water evaporation of low-cost systems remains a challenge. Here, a simple, anti-oil-fouling and macroporous aerogel based on polyvinyl alcohol (PVA), sodium alginate (SA), and polyaniline (PANi) was prepared by an in situ polymerization and freeze-drying technique. Solar water evaporation experiments were performed on the aerogel under one-sun illumination. Because of the synergistic effects of the abundant macroporous structure, roughness of the surface, and hydrophilic polymeric matrix, the aerogel displayed high solar absorption, and superhydrophilic and underwater superoleophobic surface properties. As a result, under one-sun illumination, the aerogel had a maximum solar-thermal efficiency of 91.5% and an evaporation rate of 1.46 kg m⁻² h⁻¹. More importantly, the aerogel exhibited almost identical evaporation performance in oily wastewater and saline alkali water. After 25 cycles, the photothermal conversion efficiency was found to be 87% and the aerogel was still resistant to oil contamination. The high solar vapor generation rate and antifouling functionality make the macroporous aerogel a promising material for solar-thermal water desalination, even in oil-contaminated water.