Effects of oxalate and persulfate addition to Electrofenton and Electrofenton-Fenton processes for oxidation of Ketoprofen: Determination of reactive species and mass balance analysis

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© 2018 Elsevier Ltd Electrofenton (EF) has been widely used to remove contaminants from aqueous solution, while Electrofenton-fenton (EFF), is a two stage process that employs partial electrolysis, needs further study. In addition, a combination of oxalate and persulfate with these systems (EF-Oxalate, EFF-Oxalate, EF-Persulfate, and EFF-Persulfate) could improve the oxidation capacity. This study assessed the applicability of these systems for degradation of Ketoprofen as an emerging contaminant. Under batch experiments, results showed that the order of oxidation capacity and mineralization is EF-Persulfate > EFF-Persulfate > EF-Oxalate > EFF-Oxalate > EFF > EF. Radical scavenger experiments indicated that [rad]OH is the dominant radical species in EF, EFF, EF-Oxalate, and EFF-Oxalate systems. However, both [rad]OH and 1O2 participated in oxidation of Ketoprofen in both EF-Persulfate and EFF-Persulfate processes. Fe(II)/Total Fe ratios in both solution and sludge samples decreased as oxidation capacity enhanced. Solution and sludge analyses revealed that the amount of Ketoprofen and oxidation byproducts increased in sludge over time. Carbon mass balance calculations showed that EF-Persulfate leaves the lowest amount of oxidation by-products in the system. BOD5/COD ratio analyses demonstrated that all studied systems improved biodegradability of the raw wastewater. EFF and EF-Persulfate systems had the lowest and highest operational costs, respectively. Competitive maps were developed to compare all six processes by Ketoprofen removal efficiency, mineralization capacity, and operational costs. Results confirmed that addition of oxalate and persulfate to EF and EFF systems provide good solutions to decrease the load and risk posed by Ketoprofen to water systems.

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Electrochimica Acta