Co-enhancing volatile organic compound degradation and steam generation in solar interfacial evaporation by integrating with electro-Fenton

Abstract

Solar interfacial evaporation (SIE) process offers an effective and sustainable approach for alleviating freshwater shortage, but the simultaneous evaporation of volatile organic compound (VOC) limits the application of this technique. Herein, a novel electro-Fenton assisted SIE (EF/SIE) was proposed for the first time to co-enhance steam generation and VOC removal based on an evaporator composed of graphite felt decorated with Fe/N-doped porous carbon (FeNCx/GF). This dual functional evaporator integrating photothermal and electrocatalytic technology achieved a “self-sufficient” degradation process, in which FeNCx acted as the heterogeneous electrocatalyst to in-situ produce H₂O₂ and reactive oxidizing species (ROS) for VOC degradation at evaporator interface. As a result, the VOC removal efficiency of EF/SIE system achieved 97.8±1.7% in the condensate, which was 4.8 times that of the sole SIE system. Meanwhile, due to the Joule heating during electro-Fenton process, the conversion rate from water to vapor was accelerated, reaching an evaporation rate to 1.65 kg m^-2 h^-1 at the cathodic interface, while that of the sole SIE system was only 1.43 kg m^-2 h^-1. Additionally, an external solar cell enabled complete photo-electro-thermal conversion that ensured an excellent VOC removal efficiency (99%) of the EF/SIE system in the outdoor experiment. The innovatively designed system also showed versatility in different water substrates. Thus, the dual functional evaporators successfully integrated SIE with EF, providing a sustainable and synergetic strategy for efficient treatment of wastewater containing VOC.