African Journal of Biotechnology Vol. 4 (2), pp. 191-196, February 2005          
ISSN 1684–5315 © 2005 Academic Journals

Full Length Research Paper

Effect of metal ion concentration on the biosorption of Pb²⁺ and Cd²⁺ by Caladium bicolor (wild cocoyam)

Michael Horsfall Jnr* and Ayebaemi I. Spiff

Department of Pure and Industrial ChemistryUniversity of Port Harcourt, Uniport P. O. Box 402, Choba,

Port Harcourt, Nigeria.

* Corresponding author.  E-mail: horsfalljnr@yahoo.com.

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Accepted 28 December, 2004

The influence of initial metal ion concentration of the batch sorption of Pb²⁺ and Cd²⁺ onto a low-cost biosorbent was investigated. The experimental results were analysed in terms of Langmuir and Freundlich isotherms. According to the evaluation using Langmuir equation, the monolayer sorption capacity obtained were 49.53 and 65.50 mM/g for Pb²⁺ and Cd²⁺, respectively The data further showed that, sorption of the two divalent metals onto the biomass increased with increase in initial metal ion concentration until monolayer coverage is attained. The thermodynamic assessment of the metal ion – Caladium bicolor biomass system indicates the feasibility and spontaneous nature of the process and ΔGo was evaluated as ranging from –4.55 to –6.63 KJ mol^-1 and –4.02 to –6.09 KJ mol^-1 for Pb²⁺ and Cd²⁺ sorption, respectively. The order of magnitude of the ΔG^o values indicates an ion-exchange physisorption process.

Keywords: Phytoremediation, cocoyam, adsorption, water treatment, heavy metals removal.