Hydrogel-based photothermal evaporator for efficient solar desalination and synergistic removal of volatile organic compounds

Solar-driven interfacial water evaporation for freshwater production is deemed as a crucial strategy to solve water resources scarcity. However, when the temperature at the air-water interface reaches 40 °C or higher, distilled water obtained by evaporation becomes contaminated for the complex water source rich in volatile organic compounds (VOCs), and the degree of water purification will be greatly reduced. Therefore, this study reports a carbonized carboxymethyl chitosan (C-CMCS)/sodium alginate (SA) hydrogel solar evaporator (CSE) for the synergistic desalination and removal of VOCs from water in the solar-driven vapor generating process. The CSE not only serves as an elegant photothermal absorber to promote water evaporation, but also continuously intercept VOCs with its super adsorption-photocatalysis ability, realizing the magical effect of evaporation-adsorption-degradation. The results indicated that the removal rate of phenol as the probe pollutant molecule was 95.37 % and the rate of solar water evaporation was 2.24 kg m−2 h−1, which may establish a potential tactics for purification from polluted water existing various VOCs by solar evaporation.