BIOSORPTION OF COPPER AND LEAD IONS USING WHEAT HUSK

Chemical

Abstract

The present work focused on the effectiveness of wheat husk for removal of Cu(II) ions and pb(II) ions from aqueous solution. A batch biosorption experiments was carried out using wheat husk as a biosorbent for metal removal to determined optimum biosorption conditions including pH, biomass dosage, contact time, and temperature.
Atomic Absorption Spectroscopy (AAS) adsorption results show maximum adsorption capacities of 93.41% for lead and 88% for cupper at pH 4, 5.5 respectively.
Various initial metal concentrations (from 20 to 100 ppm) and various amount of biosorbent were investigated.
The effect of pH was significant and varied with each metal. These results were found to be comparable to results reported from previous works. The results show that the removal efficiency of each adsorbent is highly dependent on pH, and metal ion removal occurred in the preferential order lead > cupper.
The FT-IR studies show that the C-O in carboxyl group of alginate directly attaches to the copper ion that leads to most of the adsorption. Langmuir, and Freundlich models were applied to describe the biosorption isotherm of the metal ions by P. tiliaceae biomass. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The monolayer biosorption capacity of P. tiliaceae biomass for Pb(II) and Cr(III) ions was found to be 75.8 mg/g and 52.1 mg/g, respectively. From the D–R isotherm model, the mean free energy was calculated as 12.7 kJ/mol for Pb(II) biosorption and 10.5 kJ/mol for Cu(II) biosorption, indicating that the biosorption of both metal ions was taken place by chemical ion-exchange. The calculated thermodynamic parameters (DG_, DH_ and DS_) showed that the biosorption of Pb(II) and Cu(II) ions onto P. tiliaceae biomass was feasible, spontaneous and exothermic under examined conditions.