Toward the Development of a Novel Electro-Fenton System for Eliminating Toxic Organic Substances from Water. Part 2. Preparation, Characterization, and Evaluation of Iron-Impregnated Carbon Felts as Cathodic Electrodes

Έτος : 2015

Author : Stella D. Sklari, Konstantinos V. Plakas, Panagiota N. Petsi, Vassilis T. Zaspalis, Anastasios J. Karabelas

New results are presented on the preparation and performance of iron-impregnated carbon electrodes for a novel electro-Fenton “filter”-type device, reported in a previous publication. Two composite Fe/carbon-felt electrodes were prepared via different procedures: one prepared under oxidizing conditions (i.e., dissolved oxygen) through immersion of carbon felt in an iron ethanolic solution (CFm-Fe), and another prepared under reduced oxidative conditions (nitrogen, ammonia, etc.) leading to in situ formation of iron nanoparticles on the carbon surface (CFm-nFe). The cathodes were characterized by X-ray diffraction (XRD), N2 adsorption−desorption (BET), scanning electron microscopy (SEM), Raman microspectroscopy, and linear sweep voltammetry (LSV). The stability and oxidation performance of these electrodes were evaluated by measuring the leaching of iron species and the degradation in aqueous medium of a common pharmaceutical compound (diclofenac), respectively. The results show that the flow-through operation leads to increased solute removal, attributed to the enhanced electrosorption on the charged electrodes and the synergistic degradation/mineralization of diclofenac due to Fenton reactions on the composite cathodes. The CFm-nFe composite cathode was the most stable, exhibiting high sorption capacity (59.2 mgDCF gCFm −1) and significant degradation/mineralization efficiency (63.7 and 31.6%, respectively) at low applied potential (1.0 V/Ag/AgCl), neutral pH and high initial pollutant concentration (∼34 mg L−1). The results demonstrate the capability of the electro-Fenton process, implemented in the novel “filter”-type device, to decontaminate neutral waters polluted by diclofenac and similar organic compounds with no addition of chemicals and with reduced energy expenditure. Research and development (R&D) needs are also outlined.