Adsorption behaviour of Pb(II), Cd(II) and Zn(II) on NALCO plant sand

Abstract

Present investigation evaluates the adsorption of Pb(II), Cd(II) and Zn(II) ions on plant sand of National Aluminum Company, Orissa, India. The XRD pattern and FTIR spectra showed goethite, alumina and silica as the major phases in the sand. Effects of various parameters such as time, pH, temperature, metal ions and adsorbent concentrations were studied. The adsorption followed pseudo second order kinetics for all the three cations. The proton stoichiometry was dependent on the nature of the metal ion showing the order Zn(II)>Cd(II)>Pb(II). The adsorption was found to be in the order Zn(II)>Cd(II)> Pb(II) with loading capacities of 47.79, 42.2 and 22.8 mg g(-1) of plant sand sample. The adsorption data was fitted to various models. The thermodynamic parameters (Delta)G(0), (Delta)H(0) and (Delta)S(0) have been evaluated. The XRD patterns of Pb(II) adsorbed plant sand sample showed that the crystallinity of silica phase was affected with the appearance of (110) plane and disappearance of (011) plane. It also disturbed the (110) plane of goethite. Cd(II) adsorbed sample showed disappearance of (011) plane of silica phase and transformation of alumina phase Al(2)O(3) to sigma-Al(2)O(3). The adsorption of Zn(II) showed. prominence of (110) plane of goethite with disappearance of sigma-Al(2)O(3) phase.