Browsing by Author "Igwe, J.C."

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    The Role of pH in Heavy Metal Detoxification by Bio-sorption from Aqueous Solutions Containing Chelating Agents
    (Academic Journals, 2005-10) Igwe, J.C.; Nwokennaya, E.C.; Abia, A.A.
    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.
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    Sorption kinetics and intrapaticulate diffusivity of As(III) bioremediation from aqueous solution, using modified and unmodified coconut fiber
    (Ecletica Quimica, 2006) Igwe, J.C.; Abia, A.A.
    The pollution and toxicity problems posed by arsenic in the environment have long been established. Hence, the removal and recovery remedies have been sought, bearing in mind the efficiency, cost effectiveness and environmental friendliness of the methods employed. The sorption kinetics and intraparticulate diffusivity of As (III) bioremediation from aqueous solution using modified and unmodified coconut fiber was investigated. The amount adsorbed increased as time increased, reaching equilibrium at about 60 minutes. The kinetic studies showed that the sorption rates could be described by both pseudo-first order and pseudo-second order process with the later showing a better fit with a value of rate constant of 1.16 x 10-4 min-1 for the three adsorbent types. The mechanism of sorption was found to be particle diffusion controlled. The diffusion and boundary layer effects were also investigation. Therefore, the results show that coconut fiber, both modified and unmodified is an efficient sorbent for the removal of As (III) from industrial effluents with particle diffusion as the predominant mechanism.