Improved aquaculture wastewater treatment and concomitant power generation in a photoelectrocatalytic fuel cell equipped with S-scheme Fe2WO6/ZnO nanorod arrays photoanode and NiFe2O4 cathode

Abstract

The treatment of aquaculture wastewater involved the elimination of refractory organics and total nitrogen (TN) concurrently was one of the towering challenges in wastewater treatment. In this work, aquaculture wastewater comprised of tetracycline (TC) and TN as well as its energy recovery was recuperated in a visible light responsive photocatalytic fuel cell (PFC) system. The S-scheme Fe2WO6 nanoparticle-anchored on ZnO nanorod array (Fe2WO6/ZNA) photoanode and NiFe2O4 nanoflower-loaded on carbon felt (NiFe2O4/CF) cathode spanned photoelectrocatalysis and catalytic chlorination, conducing both contaminant removal and power production. In the presence of optimized conditions (0.5 M Cl−, dual constructed electrodes, solution pH 7), the system exhibited a maximum power density of 1.820 mW cm−2 and removed 100 % and 88.4 % of TC and TN in 120 min, respectively. The yielded small amount of NH4+ and NO3– can also destroy by NiFe2O4/CF cathode because of its large surface area and rapid charge carrier transport. Moreover, the toxicity results testified that the treated aquaculture organic seemed to have no harmful impact on zebrafish model after PFC-chlorine treatment. The mechanism involving S-scheme Fe2WO6/ZNA-NiFe2O4/CF electrodes and PFC-chlorination enabled the core species Cl and OH partook in the photoelectrocatalytic reaction. Based on the trapping agent, electron spin resonance and liquid chromatography mass spectrometry test outcomes, the degradation pathway of TC and its by-product was also postulated.