African Journal of Biotechnology Vol. 4 (10), pp. 1109-1112, October 2005          
ISSN 1684–5315 © 2005 Academic Journals

Full Length Research Paper

The role of pH in heavy metal detoxification by bio-sorption  from aqueous solutions containing chelating agents

J.C Igwe ¹*, E.C.Nwokennaya¹ and A.A. Abia².

¹Department of Industrial Chemistry, Abia State University, P.M.B 2000 Uturu, Abia State Nigeria.

²Department of Pure and Industrial Chemistry, University of Port Harcourt, River State, Nigeria.

*Corresponding Author E-Mail: jcigwe2001@yahoo.com.

Accepted 21 July, 2005

The high level of toxic metal pollution in the environment is a result of increased human activities. The hydrogen ion concentration of solutions has been known to affect reactions in solutions. The role of pH in As(V), Pb(II) and Hg(II) ions detoxification by bio-sorption from aqueous solutions using coconut fiber and sawdust waste biomass, containing chelating agents was studied. pH characteristically influenced adsorption. Maximum adsorption occurred at pH 2 and 12 whereas minimum adsorption occurred at pH 6-8. Modification of the adsorbent by carboxymethylation and thiolation decreased the absorption capacity. As(V) metal ion was adsorbed more than Hg(II), then followed by  Pb(II) ion. A model was proposed for the action of pH on the adsorption pattern of the metal ions on the adsorbents used. Desorption studies was investigated using NaOH and H₂PO₄. Therefore, these results can serve as parameters for design of treatment plants for heavy metal detoxification using agricultural by-products, such as sawdust and coconut fiber.

Key words: pH, heavy metal, bio-sorption, adsorbents, detoxification.