Electro-Generated Alumina Synthesized by Electrocoagulation in NaCl Electrolyte: Application to the Removal of Basic Yellow 28 Dye from Aqueous Solutions

This work focuses on the synthesis and characterization of a novel mesoporous adsorbent, electrogenerated alumina (EGA_NaCl) and its application for the removal of textile dye Basic Yellow 28 (BY 28) from aqueous solutions. The investigated adsorbent EGA_NaCl was prepared by electrolysis using aluminum electrodes in NaCl electrolyte and characterized by X-Ray Diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier-transform infared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. XRD analysis revealed that the EGANaCl consisted of a mixture of AlOOH and three Al(OH)3 polymorphs, namely bayerite, gibbsite, and nordstrandite in addition to boehmite, with a specific surface area of 114.31 m²/g. Meanwhile, the EDX analysis showed the presence of cations (Na⁺ and Mg²⁺) and the anion (Cl⁻) from the salts within the alumina structure, indicating that the formed EGANaCl is influenced by the nature of the electrolyte used. Batch adsorption experiments with the prepared EGANaCl demonstrated the effective removal of BY28, with a maximum removal efficiency of 80,73%. The effects of contact time, pH, temperature, adsorption dosage, and initial dye concentration were investigated, and equilibrium was reached after approximately 60 minutes. Among the kinetic models evaluated, the pseudo – second – order model provided the best fit to the experimental data. Equilibrium data were analyzed using Langmuir, Freundlich, and Temkin models, indicating favorable adsorption of BY 28 dye onto EGANaCl. The Langmuir modelyielded a maximum theoretical adsorption capacity of 476,19 mg.g^-1. The thermodynamic analysis indicated that the adsorption process was endothermic.