Developing a highly efficient, environmentally friendly and cost-effective copper sulfide semiconductor sponge for nuclear wastewater treatment under one sun

Solar-driven interfacial evaporation technology, as a green and low-energy water treatment method, finds widespread applications in desalination, power generation, and wastewater treatment systems. In this study, a three-dimensional sponge solar evaporator was prepared using hydrophilic compounds (konjac glucomannan, KGM) and a solar absorber (copper sulfide, CuS). In a single instance of solar irradiation, the sponge demonstrated swift evaporation rates at 1.58 kg m-2 h-1, coupled with an impressive interfacial water evaporation efficiency of 94.30%. Due to the characteristics of CuS and KGM, the sponge demonstrated photothermal properties, insulation, and rapid water transport. Even under radiation (1 kW/m2) and a wide range of pH conditions (pH~2-12), the concentration of elements in radioactive wastewater could be reduced by a million times (from 1 g/L to 0.253 μg/L). Notably, during 20 cycles of testing, the sponge's evaporation efficiency only decreased by 1.13%. Furthermore, over an extended 5-hour evaporation period, it consistently sustained a steady evaporation rate of 1.577 kg m-2 h-1, showcasing its exceptional reproducibility and enduring resilience. Therefore, solar-driven interfacial evaporation technology exhibits significant potential for efficient treatment of radioactive wastewater.