Photo Augmented Copper-based Fenton Disinfection under Visible LED Light and Natural Sunlight Irradiation

Abstract

Copper-based Fenton disinfection system (Cu(II)/H2O2) is an emerging advanced oxidation process (AOP). Previous works have used reducing agents and organic ligands to improve the disinfection efficiency of Cu(II)/H2O2 system. Here, we report visible light/Cu(II)/H2O2 system showed enhanced disinfection compared to Cu(II)/H2O2 system, without the need of reducing chemical agent or organic ligand. Energy-efficient LED array was used as a visible light source in the visible light/Cu(II)/H2O2 system. Under the optimized condition, pseudo-first-order inactivation rate constant (kobs) of E. coli by visible light/Cu(II)/H2O2 (0.613 ± 0.005 min−1) was about ~8 times greater than Cu(II)/H2O2 (0.08 ± 0.011 min−1). Scanning electron microscopy and Baclight Live/Dead assay proved enhanced cell membrane damage by visible light/Cu (II)/H2O2 in comparison with Cu (II)/H2O2. Based on the bovine serum albumin (BSA) degradation and OH˙ radical measurement by visible light/Cu (II)/H2O2, a ligand to metal charge transfer (LMCT) mechanism by Cu(II)–bacterial complex is proposed for enhanced disinfection. Electrical energy efficiency (E E,1) for a log reduction of E. coli and the total treatment cost of visible light/Cu(II)/H2O2 was determined to be 32.64 KWh/m3 and 350 ₹/m3 (3.9 €/m3 or 4.74 $/m3), respectively, indicating its cost-effectiveness. Disinfection efficiency by sunlight/Cu(II)/H2O2 system (solar irradiance; 746 ± 138 W/m2) was almost comparable to LED-based visible light/Cu(II)/H2O2 system, with total treatment cost estimated to be 80 ₹/m3 (0.9 €/m3 or 1.1 $/m3).