Synthesis and characterization of eco-friendly cathodic electrodes incorporating nano Zero-Valent iron (NZVI) for the electro-fenton treatment of pharmaceutical wastewater

Abstract

The electro-Fenton process has the potential to be an efficient effluent treatment method, contingent on effective process optimization. It relies on two critical components: efficient in-situ H2O2 generation and the integration of highly reactive heterogeneous catalysts into electrode synthesis. In this study, several cathodic electrodes were synthesized, including those using zero-valent iron nanoparticles (P-NZVI), zero-valent iron nanoparticles supported on activated carbon (AC-NZVI), and El Hamma Bentonite clay loaded with zero-valent iron nanoparticles (HB-NZVI). These electrodes were fabricated using sustainable, straightforward methods and subjected to thorough physicochemical and electrochemical characterization. The goal of this research was to develop environmentally friendly cathodes, employing either pressed catalyst techniques or supporting the catalyst on carbon felt (CF) or titanium foil. These electrodes were evaluated within a heterogeneous electro-Fenton-like process, with a boron-doped diamond (BDD) anode, targeting the efficient degradation of the pharmaceutical pollutant Antipyrine (ATP). Among the tested configurations, the AC-NZVI/CF electrode demonstrated the highest degradation efficiency. Key experimental parameters, such as pH, current density, and water matrices, were systematically studied to optimize the process. Under optimal conditions (pH 7, current density of 55 mA A/cm2), 80 % mineralization of a 40 mg/L ATP solution was achieved within 150 min, with an energy consumption of just 0.3502 kWh/g. The performance of the AC-NZVI/CF electrode remained stable when applied to real wastewater and after five consecutive cycles. Comprehensive analyses using FTIR, SEM-EDS, and XPS confirmed the stability and recyclability of the electrode, showcasing its potential for sustainable wastewater treatment applications.