These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Kinetic and thermodynamic studies of the adsorption of lead (II) ions onto phosphate-modified kaolinite clay.
    Author: Unuabonah EI, Adebowale KO, Olu-Owolabi BI.
    Journal: J Hazard Mater; 2007 Jun 01; 144(1-2):386-95. PubMed ID: 17156914.
    Abstract:
    This study is on the kinetics and thermodynamics of the adsorption of Pb(2+) onto phosphate-modified and unmodified kaolinite clay obtained from Ubulu-Ukwu in Delta State of Nigeria. Increasing initial Pb(2+) concentration increased the rate of Pb(2+) adsorbed with increase in initial Pb(2+) concentration from 300 to 1000 mg/L. Increasing Pb(2+) concentration also increased the initial sorption rate h, from 1.404 to 13.11 mgg(-1)min(-1) for phosphate-modified kaolinite clay and 1.04-3.48 for unmodified kaolinite clay as Pb(2+) concentration. Increase in temperature was found to increase the initial sorption rate of Pb(2+) adsorption onto phosphate-modified adsorbent from 3.940 to 8.85 and 2.55 to 4.16 mgg(-1)min(-1) for the unmodified adsorbent. The overall sorption rate k, increased only slightly from 5.1x10(-2) to 9.7x10(-2)gmg(-1)min(-1) for phosphate-modified adsorbent, 3.8x10(-2) to 5.4x10(-2)gmg(-1)min(-1) for unmodified adsorbent. The adsorption reaction on both adsorbents was found to be chemically activated reaction and endothermic with energy of activation, E, at 500mg/L of Pb(2+) in solution as 19 and 10.68 kJmol(-1) for phosphate-modified and unmodified adsorbents, respectively. The positive values of both DeltaH degrees and DeltaS degrees obtained suggest an endothermic reaction and in increase in randomness at the solid-liquid interface during the adsorption of Pb(2+) onto the adsorbents. DeltaG degrees values obtained were all negative indicating a spontaneous adsorption process. The presence of Cd(2+) decreased both initial sorption rate and the amount of Pb(2+) adsorbed on phosphate-modified and unmodified adsorbents at equilibrium. The adsorption process follows a pseudo-second-order reaction scheme.
    [Abstract] [Full Text] [Related] [New Search]