Moringa oleifera seeds for single and simultaneous removal of Pb2+ and Cd2+ from aqueous solutions

In this study, we report the effectiveness of natural and NaOH treated Moringa oleifera seeds for single and simultaneous Pb²⁺ and Cd²⁺ from aqueous solutions. The biosorbent was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. The pH of point zero charge (pH_pzc) was determined. Effects of contact time (15-1440 min), pH of solutions (2-10), mass of biosorbent (0.1-0.5 g) and initial metal ion concentration (10-1000 mg/L) were investigated using batch tests. The results show the pretreatment of biosorbent by NaOH improve significantly uptake capacity (mg/g) of the metal ions (q (Pb²⁺) = 38.45 and q (Cd²⁺) = 17.32 ˃ q (Pb²⁺) = 31.45 and q (Cd²⁺)= 14.67). Kinetic studies shown that the more than 90 % uptake of ion metals occurring within 120-180 min and the experimental data were better describe by a pseudo-second-order model. The sorption data for non-treated and NaOH treated Moringa oleifera seeds were evaluated by the Freundlich isotherm models to describe the adsorption equilibrium.