Electro-assisted activation of peroxymonosulfate by iron-based minerals for the degradation of 1-butyl-1-methylpyrrolidinium chloride

Abstract

Abstract In the present study, the degradation of ionic liquid 1-butyl-1-methylpyrrolidinium chloride has been carried out through sulfate radicals. These radicals were generated by different methods of activation of the commercial peroxymonosulfate (PMS) formulation, Oxone®. Among them, the electro-assisted activation in presence of iron provided the best results in terms of pollutant removal and mineralization. However, radical scavenging takes place at high concentration of catalyst (Fe 2+ ) in solution, that provokes the reduction of the removal rate. In order to control the iron self-regulation in the process, iron-based minerals such as pyrite, goethite and magnetite were studied as catalyst. This process was evaluated in detail and the key factors as catalyst concentration, oxidant dosage and applied current were analyzed. It was confirmed that the removal reaction in the heterogeneous system followed pseudo-first order kinetic model. Pyrite catalyst achieved the best results and its application was optimized. The activation of PMS (10 mM) by pyrite (1 mM) under electric field (150 mA) showed a very high pollutant degradation efficiency (over 80% TOC decay in 300 min) with a low electrical energy consumption per log-unit of pollutant concentration decrease (5.45 kWh m −3 order −1 ). In addition, the use of solid catalyst eased its separation from the reaction medium and its reuse at least 5 cycles, achieving in all cases a degradation efficiency near 100% in 300 min. This fact justifies the developed process as a promising treatment for a novel class of neoteric contaminants such as ionic liquids.