Adsorption performance of groundnut and sheanut shells biochars in ternary system of toxic metals

Abstract

The choice of biomass is influenced by its availability, potential characteristics such as abundance of functional groups and large surface area. This study explored the removal of toxic metal ions from aqueous solution using groundnut and sheanut shells biochars. Groundnut and sheanut shells biochars pyrolysed at 350 ± 5ºC and 700 ± 5°C and used to remove lead (Pb), cadmium (Cd) and mercury (Hg) in ternary systems. Initial toxic metal concentrations and residual concentrations after the biochars application were measured using atomic absorption spectrophotometer. The adsorption efficiency of groundnut and sheanut shells biochars pyrolysed at 350 ± 5ºC and 700 ± 5°C in the ternary system ranged from 81.28% to 100% for lead, cadmium ranged from 43.66% to 100% and mercury ranged from 96.38% to 100%. The higher removal rates of Pb, Cd and Hg by the biochars showed the pH solutions were favourable for the adsorption. Langmuir isotherm was the model that best fit the adsorption of toxic metal ions. Groundnut and sheanut shells biochars qualify as a feasible and economic option for toxic metals removal. Hence, studies should be conducted in real polluted water to ascertain the actual effectiveness of these biochar treatments.