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

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 (k(obs)) of E. coli by visible light/Cu(II)/H2O2 (0.613 +/- 0.005 min(-1)) was about similar to 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/m(3) and 350(sic)/m(3) (3.9 (sic)/m(3) or 4.74 $/m(3)), respectively, indicating its cost-effectiveness. Disinfection efficiency by sunlight/Cu(II)/H2O2 system (solar irradiance; 746 +/- 138 W/m(2)) was almost comparable to LED-based visible light/Cu(II)/H2O2 system, with total treatment cost estimated to be 80(sic)/m(3) (0.9 (sic)/m(3) or 1.1 $/m(3)). (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The visible light/Cu(II)/H2O2 system showed enhanced disinfection compared to the Cu(II)/H2O2 system without the need for reducing agents or organic ligands. Experimental results demonstrated that the visible light/Cu(II)/H2O2 system caused significant damage to bacterial cell membranes and proposed a ligand to metal charge transfer mechanism for enhanced disinfection. Energy efficiency and cost-effectiveness of the visible light/Cu(II)/H2O2 system were determined to be favorable for practical applications.