A comparative study of the effects of various locally-prepared agro-based carbons on the In vitro adsorption of cyanide using different activating agents

Aim: The study investigated the effect of using different activating agents- Nitric acid, Zinc chloride and Phosphoric acid on the adsorption of potassium cyanide by activated charcoal. We also investigated the In vitro effect of various doses of activated charcoal from different agro-based sources (Coconut shell, Rice husk, Castor oil seed shell, Edible clay and Plantain peels) on the adsorption of cyanide. Materials and methods: 50ml of 1M potassium cyanide was pipetted into two beakers for each sample of the prepared activated charcoal ranging from 0.5 g to 2.0 g. The resultant mixtures were agitated for 1 hour and allowed to stand for 24 hours at room temperature. The mixtures were filtered using whatman filter paper. The filtrates were analyzed for cyanide concentration using ninhydrin method and the absorbance read with ultraviolet-spectrophotometry. The absorbance was then converted to cyanide concentrations in mg/dl using standard cyanide concentrations graphs. Results: The results showed some statistically significant differences in the potassium cyanide adsorption by the different samples of prepared carbon materials activated with different activating agents except for coconut shell activated with zinc chloride. The cyanide adsorption was found to be in the same range for the activated charcoal samples prepared from different sources irrespective of the doses used in the experiment. Conclusion: The adsorptive capacities of different samples of activated charcoal varied significantly with the type of chemical activating agents used in the activation of the carbon. Coconut shell activated with HNO3 and H3P04 showed the best adsorption capacity. The cyanide adsorption by the locally-prepared activated charcoal was found to be better than that of the standard commercial activated charcoal.