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|Title:||Equilibrium, kinetic and thermodynamic modeling for the adsorption of heavy metals onto chemically modified hydrotalcite|
|Authors:||Anirudhan, T S|
Suchithra, P S
|Abstract:||The adsorption of heavy metals (Cu(II), Zn(II) and Cd(II)) from aqueous solutions with tannin-immobilized calcined hydrotalcite (TA-HTC) was studied using batch experiment technique. The surface characterizations of the adsorbent were investigated. Kinetic modeling of removal of metals was done using a pseudo-second-order rate expression. The intraparticle mass transfer diffussion of metals on adsorbent represented the rate-limiting step, with the activation energy of 27.05, 24.22 and 21.96 kJ/mol for Cu(II), Zn(II) and Cd(II), respectively. Experimental results showed that the adsorption of metals was selective to be in the order of Cu(II)>Zn(II)>Cd(II). Equilibrium isotherm data for metal ions were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich and Scatchard equations. The Langmuir adsorption isotherm described the adsorption data very well at all studied temperatures. Thermodynamic parameters such as standard enthalpy (ΔH◦), standard entropy (ΔS◦), standard free energy (ΔG◦), activation energy and isosteric enthalpy and entropy were calculated and the results are discussed in detail.|
|ISSN:||0975-0991 (Online); 0971-457X (Print)|
|Appears in Collections:||IJCT Vol.17(4) [July 2010]|
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