Removal of toxic metals from aqueous phase using cacao pod husk biochar in the era of green chemistry

Abstract Cacao pod husk biochar was used as an adsorbent for the adsorption of toxic metals from aqueous phase. Cacao pod husk signifies a readily available source of eco-friendly and low-cost adsorbent in Sub-Saharan Africa that has scarcely been paid attention to. The experiment was conducted in a monosystem to determine how cacao pod husk biochar can efficiently adsorb lead (Pb 2+ ), mercury (Hg 2+ ) and cadmium (Cd 2+ ) from aqueous phase. The experiment was conducted with 100 mL of varied toxic metal concentrations of the aqueous phase with a contact time of 60 min and a constant rotary speed of 14.8 U/min. The removal efficiency of cacao pod husk biochar for Pb 2+ , Hg 2+ and Cd 2+ ranged from 99.20 to 99.94%, 99.97 to 99.99%, and 99.85 to 99.99%, respectively. Freundlich adsorption isotherm was favourable for the adsorption of toxic metals onto the cacao pod husk biochar. The toxic metals had a stronger binding affinity to the cacao pod husk biochar. Hence, cacao pod husk was efficient for toxic metals elimination.