Thermodynamic Studies on the Biosorption of Cd2+ from Aqueous Solution by Cocoa (Theobroma cacao) Pod Husk

The biosorption of Cd2+ by Cocoa (Theobroma cacao) pod husk was investigated in single metal solution. Equilibrium biosorption studies were carried out to delineate the effect of temperature variation on biosorption capacity of cocoa pod husk. The result showed that unmodified cocoa pod husk (UCPH) and modified cocoa pod husk (MCPH) exhibited maximum biosorption of 97.8 % and 99.5 % respectively at 303 K. Thermodynamic parameters such as ΔG°ads, ΔH°ads, ΔS°ads, EAads and S*ads related to Gibbs free energy, enthalpy, entropy, activation energy and sticking probability were evaluated. The result of thermodynamic investigations indicated that the biosorption reactions were spontaneous (ΔG°<0), exothermic (ΔH°<0), irreversible (ΔS°>0), diffusion controlled (- EA) and physisorption mechanism (S*<1).

Author(s): Christopher U. Sonde and Stevens A. Odoemelam

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