Synthesis of an original Bi12CoO20/ZnO nanocomposites for lead adsorption

This study explores the exceptional potential of Bi₁₂CoO₂₀/ZnO nanocomposites as highly efficient adsorbents for the removal of Lead (II) from aqueous solutions, highlighting their innovative application in wastewater treatment. These nanocomposites combine the unique properties of Bi₁₂CoO₂₀ and ZnO, offering a promising solution for environmental remediation. A comprehensive analysis has been performed on the characterization of the nanomaterials Bi₁₂CoO₂₀, ZnO, and Bi₁₂CoO₂₀/ZnO, where the structural, morphological, and physicochemical properties were examined using various characterization techniques, including thermo-gravimetric analysis, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman Spectroscopy, Brunauer-Emmett-Teller analysis for specific surface area and pH_PZC. A parametric study was carried out to evaluate the impact of the main parameters on the lead (II) adsorption process. The experimental results obtained were carefully analyzed to evaluate the kinetics of lead adsorption and to determine the adsorption isotherms by applying two-parameter models. A 99 % yield was achieved at pH 7, 0.25 g L^-1, 50 mg L^-1 initial concentration, 35 °C and an equilibration time of just 30 min, with a maximum adsorption capacity of 204.081 mg g⁻¹. The pseudo-second-order kinetic model is the most suitable model for describing the experimental data related to the adsorption of Pb(II), indicating that the removal process of Pb²⁺ ions is associated with chemical adsorption, with the rate constant determined to be 1.2732 × 10^-3 g mg⁻¹ min⁻¹ at a concentration of 50 mg L^-1. While Temkin’s equilibrium isotherm model proved more appropriate to fit the experimental data and explain the adsorption process. Additionally, photocatalytic degradation experiments under solar irradiation of two organic pollutants (Basic Blue 41 and Sunset Yellow) were conducted using the Bi₁₂CoO₂₀/ZnO nanocomposite to confirm its dual functionality, and the results were satisfactory. These findings demonstrate the nanocomposites’ potential for both adsorption and photocatalysis, marking them as promising candidates for advanced, sustainable water purification technologies.