Decolorization of Acid Yellow 23 by Photo-Electro Fenton Process using Used Alkaline Batteries

Abstract

Wastewater, a pressing environmental issue worldwide, is exacerbated by pollutants such as azo dyes (e.g., Acid Yellow 23) and the growing volume of electronic waste, including alkaline battery waste. Alkaline batteries contain harmful substances like lead, cadmium, and lithium, and the use of novel materials in batteries raises additional environmental safety concerns. Reusing materials from used batteries for wastewater treatment is gaining interest, as this approach can create a closed-loop system, converting e-waste into useful products and reducing the need for new raw materials. This study aims to determine the removal efficiency of Acid Yellow 23 using graphite electrodes derived from used alkaline batteries in the photo-electro Fenton (PEF) process and to identify the optimal conditions for maximizing this efficiency. PEF is a variant of the Fenton reaction that uses light to generate hydroxyl radicals (OH·) instead of relying solely on electrochemical methods. In this process, hydrogen peroxide (H2O2) and a photosensitizer, which absorbs light and initiates chemical reactions, are added to a solution containing the target pollutant. The combination of H2O2, ultraviolet (UV) radiation, and ferrous (Fe2+) or ferric (Fe3+) ions (as oxalate ions) produces more OH· radicals than the traditional Fenton method. The results indicated that the system achieved the highest removal rate of 88.2% under optimal conditions: an initial Acid Yellow 23 concentration of 40 mg/L, a catalyst concentration (FeSO4) of 6 mM, and an applied voltage of 4.5 V. Under these conditions, the kinetic study of dye removal followed a second-order reaction model. These findings demonstrate a significant improvement in dye removal efficiency with the introduction of light in the PEF process. This research highlights the potential of repurposing electronic waste materials for effective wastewater treatment, contributing to sustainable environmental practices and resource-efficient technologies.