Facile preparation of high strength aerogel evaporator for efficient solar-driven water purification

Abstract

Solar-driven interfacial water purification is a promising way to obtain freshwater from seawater and sewage directly, which is crucial for alleviating the energy crisis and freshwater crisis. Here, a high strength PVA-Agarose-CNT aerogel evaporator prepared by freeze-drying and dip-coating method is reported. The PVA skeleton gives the material excellent mechanical performance, and the agarose is introduced to regulate the pore structure, wettability and equivalent evaporation enthalpy for pursuing high evaporation performance. Correspondingly, the evaporation rate and conversion efficiency of the as-prepared aerogel reached 1.88 kg·m−2·h−1 and 83.45% along with a high compressive strength of ~10.0 MPa at dry status and 1.38 MPa at wet status under 80% compressive strain, which exceeded the performance of many aerogel evaporators. What's more, the wet aerogel shows fatigue resistance and self-recovery performance. The outdoor testing shows that the evaporation rate of the aerogel is 4.3 times the value of pure water, and the purified simulated seawater and organic sewage meet the drinking water standards. This research provides a simple method to prepare high-efficiency and low-cost aerogel evaporators, which will have important applications in the fields of seawater desalination and sewage treatment.