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Indian Journal of Chemical Technology (IJCT) >
IJCT Vol.17 [2010] >
IJCT Vol.17(4) [July 2010] >
| Title: | Equilibrium, kinetic and thermodynamic modeling for the adsorption of heavy metals onto chemically modified hydrotalcite |
| Authors: | Anirudhan, T S
Suchithra, P S |
| Keywords: | Hydrotalcite
Heavy metals
Adsorption
Isotherms
Kinetics
Thermodynamics |
| Issue Date: | Jul-2010 |
| Publisher: | CSIR |
| 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. |
| Page(s): | 247-259 |
| ISSN: | 0975-0991 (Online); 0971-457X (Print) |
| Source: | IJCT Vol.17(4) [July 2010]
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