Vol. 4, Issue 1 (2020)
Adsorption of lead (II) ions from aqueous solutions on low cost adsorbent prepared from coconut shell modified with polysiloxane was studied experimentally. The adsorption kinetics and thermodynamics were also investigated in batch experiments considering the time and temperature range of 5-20 minutes and 20-80 oC respectively. The removal efficiency (99.9%) of lead (II) ions was obtained at pH 8.0 and 20 minutes contact time. Pseudo-first order, pseudo-second order, Elovich and Intraparticle diffusion were employed to describe the rate of adsorption process, and the potential rate-controlling step on the adsorbent surface. This indicated that the pseudo-second order fits the data better. Thermodynamic parameters such as Gibb’s free energy (∆Go), Enthalpy (∆Ho), Entropy (∆So) and Activation energy (Ea) for the adsorption process were evaluated as -22.462 kJmol-1, -25.142 kJmol-1, -8.131 kJmol-1K-1 and -57.341 kJmol-1 respectively. These values show that the adsorption of lead (II) ions on MCSAC was exothermic and spontaneous in nature.
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