Highly active based iron-carbonaceous cathodes for heterogeneous electro-Fenton process: Application to degradation of parabens

• Published in: Process safety and environmental protection Vol. 117; pp. 363 - 371
• Main Authors: Rosales, Emilio, Buftia, Gabriel, Pazos, Marta, Lazar, Gabriel, Sanromán, M. Angeles
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01.07.2018; Elsevier Science Ltd
• Subjects: Activated carbon; Activated graphite felt; Anodic oxidation; Anodizing; Cathodes; Degradation; Disruption; Electrodes; Graphite; Heterogeneous electro-Fenton; Iron; Iron carbonaceous cathodes; Methyl paraben; Oxidation; Personal care products; Personal grooming; Preservatives; Ruthenium; Structural stability; Sulfuric acid; Iron carbonaceous cathodes; Personal care products; Anodic oxidation; Activated graphite felt; Heterogeneous electro-Fenton; Methyl paraben
• ISSN: 0957-5820; 1744-3598
• DOI: 10.1016/j.psep.2018.05.014

•Four Fe-carbonaceous cathodes were viable alternatives for heterogeneous EF.•Activated graphite felt with H2SO4 (AGF-1) proved highest mineralisation and degradation.•Maximum degradation rate (0.143min−1) at optimal conditions (100mA and pH 3).•Reusability of cathode showed high structural stability and catalytic activity.•Intermediate products were identified and degradation key steps proposed. Personal care products are known as endocrine-disrupting compounds and their degradation is a matter of concern to avoid their release into the environment. For this reason, the main objective of this study is to develop an effective advanced oxidation process able to degrade a paraben as methyl paraben (MePa). Initially, the efficiency of two electrodes, Graphite felt (GF) and Ruthenium (Ru), was compared on the degradation of MePa by anodic oxidation (AO) and electro-Fenton (EF). Near complete degradation was obtained after 1h when Graphite felt (GF) was used as cathode in EF, showing the superiority of this treatment over AO. To improve this process, heterogeneous EF through inclusion of iron into the cathode was carried out. To do that, four iron-carbonaceous cathodes were prepared based on GF (raw or activated with H2SO4, named AGF-1) showing a significant iron content (25–30%) and attaining high degradation values (95–100%) in all of them. From preliminary experiments was determined that by the use of AGF-1 as cathode the electrode performance improved, reducing significantly the treatment time required and the total amount of MePa contained in the solution had disappeared after 30min with a TOC reduction of 98.68% after 120min. The profiles of MePa exhibit an exponential decay throughout time being satisfactorily described by pseudo-first order reaction kinetic showing a maximum degradation rate of around 0.143min−1 at optimal conditions (100mA and pH 3). In addition, the selected cathode showed high structural and catalytic stability after several reuses. Finally, key steps of a plausible degradation pathway were tailored in accordance with identified and quantified intermediate products of the degradation process.