Characterization and adsorption capacity of raw pomegranate peel biosorbent for copper removal

Abstract

This study investigates the adsorption potential of natural materials waste. The biosorbent used is an untreated pomegranate peel (PGP) derived from local agricultural activities to remove copper Cu(II) ions. Natural PGP biosorbent has given, for the first time in literature, high removal efficiency for copper ions removal. The characterization of the biosorbent have been made by means Fourier Transform Infrared Spectroscopy (FTIR), TG/DTA analysis, Boehm titration and point of zero charge (pHpzc). Studied parameters are: the initial metal concentration, the pH of the solution, the particle size, the temperature and contact time. The highest Cu(II) adsorption capacity is obtained at pH = 5.8, for a particle size of 630 μm, a temperature of 313 K, a contact time of 2 h, and by increasing the initial concentration of Cu(II) solution. Langmuir, Freundlich, Dubinin Radushkevich and Temkin isotherm models have been used. Langmuir maximum adsorption capacity is 30.12 mg/g. Experimental data have been fitted to Pseudo-first order, Pseudo-second order, Intra-particle diffusion and Elovich kinetics models. Thermodynamic analysis has indicated a spontaneous endothermic adsorption of Cu(II) on pomegranate peel. The results of this study suggest that copper could be removed through an environmentally friendly process using a low cost biosorbent from an agricultural waste i.e. PGP.