Differential pulse voltammetry as a powerful tool to monitor the electro-Fenton process

Abstract This study presents the applicability of differential pulse voltammetry (DPV) technique to carry out in-depth research of electro-Fenton process. To this end, the degradation of the ionic liquid p-xylene-bis(n-pyridinium bromide) was performed, and the main parameters that influence this process were also evaluated. DPV allowed monitoring the evolution of Fe(III) reduction as redox probe, enabling to examine the degradation of ionic liquid and the effect of the potential as well as main intermediates formed throughout the process. By using DPV tool, application of sequential current intensities along the electro-Fenton process was evaluated as alternative to reduce the energy consumption keeping the same efficiency. Based on the profile of the voltammetric curves and the determination of hydroxyl radicals, currents of 50 and 600 mA were chosen for testing a bi-electrical current system. Thus, a current of 600 mA was applied for 30 min followed by 50 mA for 60 min (600, 50), and vice versa (50, 600). Both trials achieved a total organic carbon (TOC) abatement around 60%, being the system (600, 50) less energy consuming (0.24 kWh g−1 TOC) than the other system (50, 600) (5.90 kWh g−1 TOC). Furthermore, chromatographics analyses of inorganic ions allowed validating the attained results. Finally, the feasibility of this bi-electrical current process to a real matrix was successfully carried out, achieving the same TOC abatement when working with synthetic solution. This fact demonstrated the potential of the bi-electrical current electro-Fenton system and its suitability for more complex matrix, as well as the potential of DPV technique to deeply study the electro-Fenton process.