Removal of lead (II) from aqueous solutions using rice straw

Lead (Pb²⁺) is a heavy metal which is utilized in several industries and can have severe impact on the environment and human health. Research work has been carried out lately on the feasibility of using various low cost materials in the removal of heavy metals from wastewater. In this study, the feasibility of utilizing raw rice straw for removal of Pb²⁺ from water through biosorption was investigated using batch equilibrium experiments. The effect of several operating parameters on the removal of Pb²⁺ using rice straw was studied, revealing the optimum parameters at an initial Pb²⁺ concentration of 40 mg/l were: 30 min contact time at a pH of 5.5, particle size 75–150 μm and a dose of 4 g/l. A maximum removal of 94% was achieved under optimum conditions. Langmuir and Freundlich isotherm models were used for the evaluation of the equilibrium experimental data. The maximum adsorption capacity of rice straw calculated using the Langmuir isotherm was 42.55 mg/g.