Characterization and adsorption of raw pomegranate peel powder for lead (II) ions removal

The adsorption potential of raw pomegranate peel powder (PMPP) for lead (Pb) ions was investigated via batch mode at varying initial adsorbate concentration, contact time, and adsorbent concentration. The PMPP was extensively characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy-dispersion X-ray (EDX), thermogravimetry (TG), and differential scanning calorimetry (DSC) analyses. The instrumental characterization results confirmed the presence of important functional groups and surface texture/morphology that played key roles during the lead ion adsorption. Description of the experimental equilibrium data by nonlinear Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm models was elaborately presented in the study. The experimental kinetic data were fitted to the Pseudo-first-order, Pseudo-second-order, Intra-particle diffusion, and Elovich models. The Temkin model satisfactorily predicted the isotherm data. Meanwhile, the intra-particle diffusion model was best at predicting the kinetic data at adsorbate concentration of 150 mg/L, while the Elovich model emerged as the best fit at 300 mg/L concentration. This study shows that lead ions could be efficiently removed using raw pomegranate peel powder.