Heterogeneous electro-Fenton as plausible technology for the degradation of imidazolinium-based ionic liquids

• Published in: Chemosphere (Oxford) 2018-05, Vol.199, p.68-75
• Main Authors: Poza-Nogueiras, V., Arellano, M., Rosales, E., Pazos, M., González-Romero, E., Sanromán, M.A.
• Format: Article
• Language: English
• Subjects: 1,3-Bis(2,4,6-trimethylphenyl)imidazolinium chloride; Differential pulse voltammetry; Heterogeneous catalysis; Heterogeneous electro-Fenton; Iron alginate spheres; Screen-printed carbon electrode
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2018.01.174

Conventional water treatments are generally inadequate for degradation of emerging pollutants such as ionic liquids (ILs). The use of heterogeneous electro-Fenton (HEF) has attracted great interest, due to its ability to efficiently oxidize a wide range of organic pollutants operating in cycles or in continuous mode. In this study, the removal of a complex IL from the imidazolinium family (1,3-Bis(2,4,6-trimethylphenyl)imidazolinium chloride), by means of HEF using iron alginate spheres as catalyst has been investigated, resulting in significant TOC decay after 6 h. The optimization of the key process parameters (current, IL concentration and catalyst dosage) has been performed using a Box-Behnken experimental design and achieving 76.98% of TOC abatement in 2 h of treatment. Current proved to be a crucial parameter and high catalyst dosage is required to achieve the maximum removal. In addition, an insight about the availability of iron into the reactor and the evolution of several intermediates has been carried out by employing differential pulse voltammetry on screen-printed carbon electrodes. The evolution of the different voltammetric peaks confirmed the influence of iron release, and the generation of several iron complexes has permitted the comprehension of the degradation pathway, which has been validated by chromatographic techniques. [Display omitted] •Ionic liquid successfully degraded by electro-Fenton using iron alginate spheres.•Heterogeneous electro-Fenton (HEF) optimized by Box-Behnken experimental design.•Current is a crucial parameter in HEF and high catalyst dosage is required.•Iron and its complexes were monitored by DPV on screen-printed electrodes.•DPV allowed elucidating the main degradation pathway of [IMes.HCl].