High-efficiency and sustainable sodium humate aerogel evaporator for solar steam generation

Abstract

The utilization of solar interface evaporation technology (SIET) for freshwater production from seawater and sewage is a sustainable, green, viable, and promising approach. However, the absorption rate of sunlight, evaporation rates, and high costs still pose large-scale solar steam generation. In this paper, a novel aerogel (named SAS) was prepared by graft copolymerization with sodium alginate (SA), acrylic acid (AA) and sodium humate (SH) in aqueous solution, using N, N′-Methylenebisacrylamide (MBA) as crosslinker and ammonium persulfate (APS) as initiator, which has high light absorption (90 %), high porosity (87.96 %), superhydrophilicity (35 ms), low thermal conductivity (0.23 W m−1 k−1). The evaporation rate of SAS aerogel can reach up to 1.66 kg m-2h−1 under 1 kW m−2 light intensity, and the reusability and reliability of SAS aerogel are verified by 10 cycles of experiments. The utilization of this SAS aerogel holds significant implications for the design and fabrication of cost-effective, high-performance solar steam evaporation systems, thereby offering promising solutions to address global freshwater shortages and enhance wastewater treatment efficiency.