Photoelectrochemical Oxidation of Ceftriaxone in Aqueous Solutions Using a KrCl Excilamp (222 nm)

The kinetics of the photoelectrochemical oxidation (PEO) of the antibiotic ceftriaxone (CEF) was studied using a Ti/RuO2–IrO2 anode, a stainless steel cathode, and UV radiation of a KrCl excilamp (222 nm) in deionized water and treated municipal wastewater. In both water matrices, the degradation rates were the highest, with UV irradiation making the predominant contribution. At the first stage of PEO in wastewater, the rate constant is comparable to that found in deionized water due to increased generation of secondary radicals involving the matrix anions. At the second stage, the degradation rate decreases, and electrochemical oxidation (EO) makes a certain contribution. During PEO, mineralization of the total organic carbon (TOC) is higher: 45 and 67% in wastewater and deionized water, respectively. In terms of UV radiation dose, PEO is a more energy-efficient process, the dose required for 90% degradation of CEF in wastewater (20 mJ/cm2) being 3.75 times less of that in deionized water. The results indicate that it is promising to use PEO for efficient degradation and mineralization of bioresistant antibiotics in wastewater aftertreatment processes.