Regeneration and Reusability of Bleaching Earth as a Sustainable Material for Tartrazine Yellow (E102) Removal: Insights into Kinetic Mechanisms

Abstract

Anionic dyes, like tartrazine, have harmful effects on aquatic life and humans and therefore, their elimination from industrial effluents needs to be taken very seriously. The elimination of tartrazine yellow from wastewater resulted in the application of adsorption as an economical and effective treatment approach. The use of regenerated bleaching earth and regenerated bleaching earth modified with urea as adsorbents for tartrazine yellow from simulated wastewater served as the foundation for this study. The sorption process was run in batch mode with different process parameters. The Fourier transform infrared spectrophotometry (FTIR) and X-ray diffraction analyses of the adsorptive material demonstrated the existence of surface functional groups while scanning electron microscopy revealed a porous structure. At a pH of 3, with an adsorbent dosage of 50 mg and a dye concentration of 50 mg/L, the highest dye uptake was achieved with an adsorption efficiency of 48%. The models that best matched the kinetics were the pseudo-first-order, pseudo-second-order and Elovich (R² > 0.95) models. The dye fixation process took 140 minutes to reach adsorption equilibrium. The outcomes of the sorption study demonstrated competition between chemisorption and physisorption, and that bleaching earth can be successfully regenerated, and used as an efficient sorbent for eliminating tartrazine yellow in an aqueous solution.