Kinetic Studies On The Removal Of Heavy Metal Ions (Ni(II), Cd(II) AND Pb(II)) Ions From Aqueous Solution Using Sphenostylis Stenocarpa (African Yam Bean) Pod:- Loveday, Kate C.

ABSTRACT

The potential of Sphenostylis stenocarpa (African yam bean) pod for adsorption of Cd(II), Ni(ID and Pb(II) ions from aqueous solutions was determined by batch process. The influences of parameters such as pH, contact time, metal ion concentration on metal adsorption were investigated. It was observed that these heavy metal ions showed maximum adsorption at pH 7.0. Kinetic modeling of Cd(II), Ni(II) and Pb(II) ions using pseudo-first order yielded K; values of -0.001gmgmin', -0.014gmgmin' and 0.026gmgmin·• respectively, and for the pseudo-second order, the K; values of Cd(II), Ni(II) and Pb(II) ions are 1.2 I 8 Ix 10· 7 ,0.1333 and 2.0056x10° gmgmin' respectively. The adsorption capacity (qe) values are 55.556, 50.00 and 52.6316mg/g for Ni(ll), Cd(II) and Pb(II) ions respectively. Kinetic modeling of the results shows that the pseudo-second order model best describes the process and mechanism of adsorption shows that the process was film diffusion controlled for Cd (II) ions but intra-particle diffusion controlled for Ni(Il) and Pb(II) ions. The affinity of the adsorbent for the adsorbate for the metal ions also follows the trend Ni(II) > Pb(II) > Cd(II). This will serve as parameters to consider in the design of treatment plant for these heavy metals detoxification using Sphenostylis stenocarpa (African yarn bean) pod.