KINETICS STUDIES OF SORPTION OF Pb(II), Cd(II) AND Ni(II) IONS FROM AQUEOUS SOLUTION USING FUNCTIONALIZED CALOPO (Calopogonus mucunoides) SEED POD.

O. K Amadi, F. K Ekuma,, I. A Okoro, C. C Aleruchi

Abstract


In this research work, the potential of calopo seed pod, an agricultural waste available in large quantity mostly in Southern  region  of  Nigeria,  was  used as low-cost adsorbent for  the removal  of  the following metal  ions:  Pb(II), Cd(II) and Ni(II) from aqueous solution. The effects of solution pH and contact time for the process were evaluated using batch adsorption technique. The kinetics of the sorption process were investigated using pseudo first-order, pseudo second-order, Elovich, Mckay and Poot diffusion and liquid film diffusion models. Results showed that the adsorption process was fast and that equilibrium was achieved within 40 min for Pb(II) ions and 60 min for both Cd(II) and Ni(II) ions. Results further showed that the optimum pH for the study occurred at pH 6.0 with maximum % removal of 95.35 %, 99.48 % and 98.32 % for Pb(II), Cd(II) and Ni(II) ions respectively indicating that the affinity of the metal ions sorption for the adsorbent followed the order: Cd(ll) > Ni(ll) > Pb(ll). Adsorption process was found to follow pseudo second-order kinetics judging by the high correlation coefficients (R2 values) obtained as compared to the other kinetic models. Moreover, the calculated equilibrium adsorption capacities (qe values) of 52.63 mg/g, 50.00 mg/g and 47.67 mg/g  for Pb(II), Cd(II) and Ni(II) ions respectively were close to the experimental qe values of 49.26 mg/g, 47.25 mg/g and 49.71 mg/g for the three metal ions following the initial order. The transport mechanism of the process was found to be a combination of liquid film and intra-particle diffusion controlled mechanism. The results from this study will serve as design parameter in wastewater treatment plant for Pb(II), Cd(II) and Ni(II) ions detoxification using calopo seed pod.

Keywords: Adsorption kinetics, biosorption, Calopogonium muconoides, kinetic models, metal ions.


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Chemical Society of Nigeria