ADSORPTION OF LEAD, CADMIUM, AND MERCURY IONS IN AQUEOUS SOLUTION USING GROUNDNUT AND SHEANUT SHELLS BIOCHARS

Abstract

The adsorption performance of toxic ions and effect of initial pH using groundnut shells and sheanut shells biochars were studied to ascertain the practical and theoretical basis of the use of biochars to remediate water pollution. Biochars were prepared using groundnut and sheanut shells as the feed stocks. The removal efficiencies of lead (Pb) were 100%, > 65.90% for cadmium (Cd) and 96.70% for mercury (Hg) in mono systems of 5, 10, 25 and 50 mg/l. The maximum Langmuir capacity ranged from 400 to 2000 mg/g for Cd and 232.56 to 312.50 mg/g for Hg by biochars. The adsorption of toxic metal ions by groundnut and sheanut shells biochars showed similar removal efficiencies. Adsorption of Pb, Cd and Hg were effective in the varied pH which was largely dependent on the characteristics of groundnut and sheanut shells biochars determined by the pyrolysis conditions and nature of feed stock. Langmuir isotherm was the model that best fit the adsorption of toxic metal ions onto the biochars. Groundnut and sheanut shells biochars have proven to be good candidates for the remediation of water polluted with toxic metals in mono systems.