Evaluation of the Adsorptive Capacity of some Activated Plant Materials on Cyanide: An In vitro Study

Abstract

Background and Purpose: Chemical intoxication of dietary origin is one of the major health problems confronting the global community. Cyanide is a very toxic chemical which reacts and forms a stable complex with iron in cytochrome oxidase thereby inhibiting oxidative phosphorylation. Adsorbents are carbon materials that attract poisons to their surfaces thus preventing the absorption of poisons into the body. The clinically available activated charcoal is expensive and often not readily available. Methods: Four (4) different concentrations ranging from 0.5 g/dL to 2.0 g/dL of activated carbon from plantain peels, castor oil seed shells, coconut shells, and rice husks were used to prepare adsorbent samples. The same range of concentrations was used for activated charcoal (standard). Each concentration was introduced into a 1 L of pyrex beaker containing 250 mL aqueous solution of 1 mol/mL of potassium cyanide. The cyanide-ninhydrin adducts obtained were subjected to UV-spectrophotometry, and the degree of adsorption of cyanide by the various activated carbon samples was determined. Results: Plantain peels showed the least amount of un-adsorbed cyanide (20.03±0.48 mg/dL), followed by coconut shells (24.34±0.43 mg/dL), next was castor oil seed shells (26.48±0.36 mg/dL). These values were all significantly (P<0.0001) lower than the value obtained for the commercial (standard) activated charcoal (36.87±0.02 mg/dL). At the sample amount of 2.0 g/dL, the lowest un-adsorbed cyanide concentration (15.28±0.83 mg/dL) was seen in the combination of plantain peels + castor oil seed shells + coconut shells. Conclusion: Adsorbents prepared from some plant materials showed better in vitro adsorptive capacity for cyanide than the standard (commercially and clinically available) activated charcoal. The combination of the materials also showed better adsorption for cyanide than the single agents. They therefore seem more efficacious and may also be cheaper than the commercial product.