Microwave assisted modified macadamia nutshells/Cu-Mn oxide composite for the removal of Pb(II) from aqueous solution

The present study reports a novel composite material synthesized from acid modified macadamia nutshells (AMN) and Cu-Mn oxide under microwave heating for the removal of lead ions (Pb(II)) in water. The surface characterization of the material was carried out using powder XRD, FTIR, EDS, SEM, TGA, XPS, TEM, BET and zeta sizer. A series of batch adsorption experiments were carried out to investigate the adsorption behaviour of Pb(II) on AMN-Cu-Mn oxide. The adsorption kinetics and isotherms studies follow a pseudo second order model and Langmuir isotherm respectively with a maximum adsorption capacity of 34.5 mg/g at room temperature. The thermodynamic parameters indicate the endothermic and spontaneous nature of Pb(II) adsorption. The material adsorbed more than 95 % of Pb(II) in the presence of competing cations. AMN-Cu-Mn oxide was successfully recycled 4 times using 0.1M HCl as leachate; 85 % Pb(II) was desorbed during the last adsorptiondesorption cycle.