African Journal of Biotechnology Vol. 5 (16), pp. 1475-1482, 17 August 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Lead (II) and nickel (II) adsorption kinetics from aqueous metal solutions using chemically modified and unmodified agricultural adsorbents

ABIA, A. A.* and ASUQUO, E. D,

Department of Pure and Industrial Chemistry, University of Port Harcourt. P. M. B. 5323, Choba, Port Harcourt, Nigeria.

*Corresponding authors E-mail: abiauniport2005@yahoo.com. Phone: 234 – 08036685125.

Abbreviations: a, constant in intraparticle diffusion model depicts adsorption mechanism; C_o, initial metal ion concentration (mgL^-1); C_t, concentration of metal ion at time t (mgL^-1); K_id, intraparticle diffusion rate constant (min^-1); R_em, percentage of metal removed; 1.0MOPF, 1.0 M mercaptoacetic acid modified oil palm fruit fibre; 0.5MOPF, 0.5 M mercapto-acetic acid modified oil palm fruit fibre; and UOPF, unmodified oil palm fruit fibre.

Accepted 21 August 2006

This paper discusses the kinetics of lead (II) and Nickel (II) ions adsorption from aqueous solutions using chemically modified and unmodified agricultural adsorbents at 28°C, pH 6.2 and 0.01M NaCl ionic strength.  The removal of the two metals were found to increase with increase in chemical modification, the sequence being 1.0MOPF>0.5MOPF>UOPF.  In addition Nickel (II) had a higher percentage removal than lead (II). The intraparticle diffusion rate constant (K_id) were determined to be 63.023 min^-1 (Ni²⁺) and 38.212 min^-1 (Pb²⁺) for the 1.0MOPF adsorbent. The results show that the intraparticle diffusion model fits the sorption of lead (II) with higher coefficient of determination (r²) than Nickel (II), thereby indicating that the intra-particle diffusion may be the rate limiting step for Pb²⁺ sorption.  The results from this study indicates that a good adsorbent for the removal of Ni²⁺ and Pb²⁺ can be obtained from both chemically modified and unmodified oil palm fruit  fibre.

Key words: oil palm fruit fibre, mercaptoacetic acid, intraparticle diffusion, adsorbent, chemical modified and agricultural-by-product.