Effect of Acid and Alkaline Activation of Coconut Husk based Biochar for the Removal of Cadmium (II) ion from Aqueous Solution

Abstract

In the environment, cadmium is toxic to plants, animals and micro-organisms, therefore its removal from industrial wastewater before discharging into recipient environment is necessary. The objective of this paper is to evaluate the effect of acid and alkaline activation of coconut husk based biochar for the removal of cadmium ion from aqueous solution. Data obtained reveal that coconut husk based Activated Carbon (A.C) exhibited high adsorption efficiency at a high pH of 10 with 99.8% and 99.6% of Cd (II) removal for alkaline and acid chemical activation respectively. The experimental kinetics data fit with the pseudo-second order model and the Freundlich isotherm model was found to be suitable for both type of chemical activation. Although, biochar activated with CaCl2 and H3PO4 showed good adsorption capacity of Cd (II) metal ion in aqueous solution but the Freundlich isotherm model applied in this study with (n) values of acid and alkaline A.C to be (1.12 and 0.72) respectively, depicts that Acid A.C has shown to have a better adsorption characteristics than alkaline coconut husk based activated carbon.