Abstract: Integrating the evaporation of seawater at the interface with the treatment of wastewater presents an encouraging approach to address urgent energy and environmental issues. Nevertheless, the development of dual-function evaporators endowed with synergistic photothermal advanced oxidation catalytic properties presents significant hurdles. In this study, a black g-C₃N₄/loofah/chitosan (BCN/LF/CS) hydrogel was developed, demonstrating remarkable abilities in absorbing sunlight and converting it thermally. This innovation is intended for solar-driven evaporation and the thermal activation of persulfate (PS), which aids in the degradation of tetracycline (TC) contaminants. Test results demonstrated that under singular sunlight irradiation, BCN/LF/CS hydrogel not only achieves an impressive evaporation rate of 2.5 kg m^-2 h^-1 but also effectively catalyzes the decomposition of PS, leading to substantial degradation of TC (Concentration: 50 mg/L, PS dose: 0.03 g/L, 86 % degradation rate: in 3 h). The research unveils innovative and ingenious methodologies to alleviate freshwater scarcity and address the pressing issue of water pollution which introduces a groundbreaking approach to the development of advanced solar evaporators that seamlessly integrate seawater desalination with sewage purification.

Key words: Solar evaporator, Persulfate activation, Hydrogel, Photothermal, Black g-C₃N₄