In this study, a sustainable nanocomposite was synthesized using the stem waste of Brassica oleracea var. italica, dually doped with Zn and Al (Zn/Al@BOI), through a chemical co-precipitation method. The material was designed for the efficient adsorptive treatment of wastewater to remove Malachite Green (MG). The structural and surface features were analyzed using SEM, BET, EDX, XRD, FTIR, XPS, and TGA. The presence of Zn and Al was confirmed by EDX and XPS, while BET surface area analysis confirmed a notably high value of 80.53 m².g-1, suggesting the strong adsorption capability of the material. To investigate its adsorption behavior, a set of batch tests was conducted, focusing on the influence of time, pH, adsorbent dose, MG dye concentration, and temperature. Using RSM with a CCD, the ideal operational conditions were determined to be approximately 29.64 min of contact time, 0.29 g.L-1 dosage, pH 7.96, and 20 ppm dye concentration, resulting in a greater efficiency of 97.31%. The equilibrium data best fit the Freundlich isotherm (R² = 0.9957), while the Langmuir model analysis revealed a monolayer capacity of 336 mg. g-1. The adsorption kinetics were effectively represented by the pseudo-2nd-order model, and the thermodynamic findings revealed a spontaneous, endothermic, and physisorption-driven process.
Thikkada et al. (Thu,) studied this question.