KINETICS AND MECHANISM MODELLING OF Pb(II) AND Ni(II) IONS SORPTION FROM AQUEOUS MEDIUM: EVALUATING THE PERFORMANCE OF Curcuma longa RHIZOME IN THE TREATMENT OF WASTE WATER.

Abstract

In this research Curcuma longa Rhizome, an agricultural product, available in large quantity in northern Nigeria, were used as low-cost adsorbent for removal of Pb(II) and Ni(II) ions from aqueous medium. Batch operation was used to study the equilibrium behaviour of Curcuma longa rhizome. The effect of solution pH, and contact time on the adsorbent for the removal of Pb(II) and Ni(II) ions were evaluated. To study the adsorption kinetics of Pb(II) and Ni(II) ions onto Curcuma longa Rhizome, pseudo-first-order, pseudo-second-order as well as three diffusion models: intraparticle diffusion model (Weber and Morris model), film diffusion model (McKay model) and liquid film Models were used. The sorption kinetics can be described well by the pseudo-second-order model due to the closeness between the qexp ( 49.26 mg/g) and qcal (52.63 mg/g) for Pb(II) and qexp (57.60) and qcal (55.56 mg/g) for Ni(II) ions. Moreover, the rate limiting step are liquid film and intraparticle diffusion controlled. In addition, the results suggest that Curcuma longa Rhizomes are very effective adsorbent for the removal of Pb(II) and Ni(II) ions from aqueous medium. This will serve as an indicator to consider in the design for waste water treatment plant for heavy metal detoxification using Curcuma longa Rhizome.