A self-sufficient catalytic nanofiber evaporator for solar-driven efficient water purification through in-situ hydrogen peroxide generation

Abstract

Solar-driven interfacial water evaporation (SDIWE) is an emerging technology for the production of clean water driven by inexhaustible energy source, but its application suffers from volatile organic compounds (VOCs) escaping into condensate water. Herein, a bifunctional SDIWE system integrated with Fenton process was proposed to achieve self-sufficient (not adding any additional chemicals to feed water) high-quality freshwater production from VOCs-contained wastewater through in-situ hydrogen peroxide (H2O2) generation. The hybrid SDIWE system based on AgNPs (Ag nanoparticles)@graphitic carbon nitride (g-C3N4)/beta-iron hydroxide oxide (β-FeOOH)-Polyacrylonitrile (AgG/Fe-PAN) nanofiber membrane exhibited an excellent evaporation performance (1.61 kg m-2h−1) under one sun (1 kW m−2). Significantly, in the absence of external oxidant source, the phenol removal rate in condensate water reached 98.4 ± 0.2 % due to the synergic photocatalysis technology and Fenton reaction, which was 6.1 times that of sole SDIWE (16.2 ± 0.5 %). Mechanism analysis reveals that H2O2 was effectively in-situ generated by AgNPs@g-C3N4 particles (∼18.8 μM at 4 h). Subsequently, the produced H2O2 was further activated to •OH radicals via β-FeOOH that ensures the VOCs decomposition during rapid steam generation. Meanwhile, the hybrid system not only exhibited an excellent phenol removal rate of 91.6 ± 0.6 % in wide pH ranges (1–11), but also ensured a good removal performance for various organic pollutants and excellent antibacterial properties. To sum up, the hybrid system has successfully integrated SDIWE technology with various advanced oxidation processes (AOPs), providing a novel way for the pollution-free production of high-quality clean water during the SDIWE process for water purification.