Removal of lead (II) and copper (II) from aqueous solution using pomegranate peel as a new adsorbent

The effective removal of heavy metals from aqueous wastes is among the most important issues for many industrialized countries. Removal of lead (II) and copper (II) from aqueous solutions were studied using pomegranate peel (raw), activated carbon prepared from pomegranate peel (AC1) and activated carbon prepared from chemically treated pomegranate peel (AC2 and AC3). Batch adsorption experiments were performed as a function of pH, contact time, solute concentration and adsorbent dose. The optimum pH required for maximum adsorption were found to be 5.6 and 5.8, for lead and copper respectively. The experimental equilibrium adsorption data are tested for the Langmuir, Freundlich and Temkin equations. Results indicate the following order to fit the isotherms: Langmuir > Temkin > Freundlich in case of lead ions and Freundlich > Temkin > Langmuir in case of copper ions. Adsorption kinetics data were modeled using the pseudo-first and pseudo-second order, Elvoich equations and intraparticle diffusion models. The results indicate that the second-order model best describes adsorption kinetic data.

The present study shows that activated carbon prepared from chemically treated pomegranate peel is an effective adsorbent for the removal of lead and copper ions from aqueous solutions. The adsorption process is a function of the adsorbent and adsorbate concentrations, pH and time of agitation. The effective pH for the lead and copper removal were 5.6 and 5.8, respectively. Equilibrium was achieved practically in 2 h. The equilibrium sorption data are satisfactorily fitted in the order: Langmuir > Temkin > Freundlich in case of lead ions and Freundlich > Temkin > Langmuir in case of copper ions. Adsorption kinetics follows pseudo-second order kinetic model. Kinetic results showed that both bulk and intra-particle diffusion are effective adsorption mechanisms. The results would be useful for the design of wastewater treatment plants for the removal of lead and copper.