Removal of lead from aqueous solutions using rice husk

Rice husk, an agricultural waste, was studied as a potential scavenger of lead from various aqueous solutions. Physicochemical parameters such as selection of appropriate electrolyte, shaking time, and the concentrations of adsorbent and adsorbate were studied to optimize the conditions to be utilized on a commercial scale for the decontamination of effluents using a batch technique. Maximum adsorption was observed with 0.01 mol.dm(-3) acid solutions (HNO3, HCl, H2SO4 and HClO4) using 1000 mg of adsorbent for a 4.82 X 10(-5) mol.dm(-3) lead concentration in less than 10 minutes equilibration time. Studies show that the adsorption decreases with an increase in the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the 9.65 x 10(-5) to 4.83 X 10(-3) mol.dm-3 range of lead concentration. The characteristic Freundlich constants, i.e., 1/n = 0.93 +/- 0.04 and A = 19.86 +/- 0.82 m.mol.g(-1),have been computed for the sorption system. Thermodynamic parameters, i.e., Delta G degrees, Delta S degrees, and Delta H degrees, have also been calculated for the system.