Structure-dependent degradation of pharmaceuticals and personal care products by electrocatalytic wet air oxidation: A study by computational and experimental approaches

Abstract

The world-wide accumulation of pharmaceuticals and personal care products (PPCPs) in water environment emphasizes the urgent development of effective PPCPs removal technologies. In this work, the feasibility of electrocatalytic wet air oxidation (ECWAO) technology for the treatment of six typical PPCP pollutants was evaluated, and their degradation pathways were studied. The ECWAO reaction of PPCPs was found to fit to the first-order kinetics, with apparent rate constants in an order of triclosan (0.206 min−1) > bisphenol A (0.104 min−1) > tetracycline (0.062 min−1) > ciprofloxacin (0.041 min−1) > ibuprofen (0.035 min−1) > sulfamethoxazole (0.026 min−1). The PPCP compounds with aromatic ring and oxygenated groups were mineralized at relatively higher efficiencies than the fused-ring or sulfonamide compounds. The degradation pathways of the PPCPs were proposed based on the detected intermediates and with the aid of quantum chemical calculation. Toxicity and biodegradability analyses demonstrated the ECWAO reaction was able to diminish the toxicity of PPCPs and improve their biodegradability. The specific energy consumption (SEC) of the ECWAO system varied from 11.7 to 19.53 kW h kg-TOC-1 in treating the different PPCPS. Such values were at least one order of magnitude lower than the SECs of conventional electro-oxidation systems. Practice on real lake water treatment showed promising potential of the ECWAO technology for cost-effective and safe elimination of PPCPs pollution.