A novel sandwich structure ACF/CC@FeOCl as bifunctional cathode for efficient mineralization of trimethoprim in the heterogeneous electro‐Fenton process over a wide pH range

Abstract

BACKGROUND: It would be highly advantageous to develop a heterogeneous electro-Fenton (HEF) system in which the catalyst is fixed to recycle easily and the electrode itself can produce and activate H 2 O 2 simultaneously. In this study, a new sandwich-like bifunctional cathode using carbon cloth (CC) loaded with FeOCl nanoparticles and activated carbon fiber (ACF) was fabricated and used in the HEF process for the degradation of antibiotic trimethoprim (TMP). RESULTS: Experimental results showed that the activated carbon fiber and FeOCl-modified carbon cloth cathode (ACF/ CC@FeOCl) exhibited a promising catalytic performance to reduce O 2 to generate H 2 O 2 on the surface of ACF and activate H 2 O 2 to generate hydroxyl radicals ( • OH) at the active sites of FeOCl nanoparticles, thus enabling a rapid TMP degradation in a wide pH range (3-9). Various influencing factors, such as applied cathodic current, pH and TMP concentration, were investigated, and the optimal condition was found at 0.36 A, pH 3.0, and 100 mg L −1 TMP, where 99.7% TMP was degraded within 90 min and 74.4% total organic carbon (TOC) was removed within 360 min. Under the condition of 0.36 A and initial pH 6.8, 100 mg L −1 TMP was completely degraded within 120 min and the mineralization efficiency could achieve 61.5% within 360 min. The coumarin fluorescence probing technique and radical quenching experiments revealed that • OH was the predominant reactive oxygen species (ROS) in the ACF/CC@FeOCl-HEF process.CONCLUSION: The reusability and stability tests showed that the ACF/CC@FeOCl cathode has excellent performance and good stability, and this is very promising for the efficient degradation of refractory organic pollutants in the HEF process.

Electrochemical Hydrogen Peroxide Generation and Activation Using a Dual-Cathode Flow-Through Treatment System: Enhanced Selectivity for Contaminant Removal by Electrostatic Repulsion

“…Additionally, use of a dual-cathode system avoids inefficiencies inherent in single electrode systems in which the same potential is applied for reductive processes that have different electrochemical potentials (Text S1). As a result of this inefficiency, systems employing single composite electrodes often produce excess H 2 O 2 or apply current to solutions after H 2 O 2 has been depleted. , In addition to increasing energy consumption, the mismatch between H 2 O 2 production and use can result in the presence of an unwanted oxidant in treated water (i.e., H 2 O 2 ) as well as the production of other unwanted products (e.g., H 2 ). , Finally, electrochemical generation of H 2 O 2 increases localized solution pH values, which can decrease the efficiency of H 2 O 2 activation …”

“…20,21 In addition to increasing energy consumption, the mismatch between H 2 O 2 production and use can result in the presence of an unwanted oxidant in treated water (i.e., H 2 O 2 ) as well as the production of other unwanted products (e.g., H 2 ). 22,23 Finally, electrochemical generation of H 2 O 2 increases localized solution pH values, which can decrease the efficiency of H 2 O 2 activation. 24 Most previous attempts to employ separate electrodes for H 2 O 2 generation and activation were simply a combination of processes that were not optimized to maximize efficiency and avoid the generation of unwanted products.…”