Equilibrium and Thermodynamic Consideration of Cd2+, Ni2+ and Pb2+ Removal from Aqueous Solution onto Treated and Untreated Cola Nitida Waste Biomass

Adsorption principles and techniques are used in the treatment of effluent water from industries and other sources. The use of adsorbent such as Cola nitida husk has been recommended as one of the ways of reducing the concentrations of heavy metals in wastewater. In this study, the influence of pH and temperature on the adsorption of Cd2+, Ni2+ and Pb2+ onto unmodified and modified Cola nitida waste was investigated. The result showed that Cd2+, Ni2+ and Pb2+ exhibited maximum adsorption of 99.99 mg/g by unmodified Cola nitida husk at pH of 2-10 for Cd2+; pH of 2, 4, 8 and 10 for Ni2+; pH of 2, 6, 8 and 10 for Pb2+ while 99.78 mg/g Cd2+, 99.51 mg/g Ni 2+ at pH 6 and 99.67 mg/g Pb2+ at pH of 2 was achieved by modified Cola nitida husk. 99.96 mg/g Cd2+, 99.99 mg/g Ni2+ and 99.92 mg/g Pb2+ at 303K (30 0C) was also achieved by unmodified Cola nitida husk while 99.92 mg/g Cd2+, 99.64 mg/g Ni2+ and 98.90 mg/g Pb2+ at 303k (30 0C) was equally achieved by modified Cola nitida husk. The values of Ea, ??S?_ads^0, ??H?_ads^0 and ??G?_ads^0 gotten showed that the adsorption process is by physical adsorption, spontaneous, feasible and exergonic (release of free energy), endothermic and occur with increasing degree of orderliness.