Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Congo Red onto Modified Kaolinite Clay

International Journal of Chemistry | Vol. 3, No. 1, January 2012 | pp. 1–9

DOI: 10.46882/2012/IJC/000040

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Congo Red onto Modified Kaolinite Clay

Names of Authors: A. D. Yusuf¹, T. S. Ani²*

Authors’ Affiliations:
¹Department of Industrial Chemistry, Federal University of Technology, Yola, Nigeria.
²Department of Electronic and Chemical Engineering, Enugu State University of Science and Technology, Enugu, Nigeria.

Abstract: The discharge of highly stable anionic azo dyes like Congo Red from textile processing factories presents severe remediation challenges for municipal sanitation networks. This study examines the adsorptive uptake performance of a surfactant-modified kaolinite clay (SMK) optimized via chemical treatment with cetyltrimethylammonium bromide (CTAB). Structural parameters of raw and functionalized clays were characterized using X-ray diffraction (XRD) and FT-IR spectroscopy. Adsorption operations were conducted via batch runs, monitoring shifts in contact period, baseline solution pH, initial dye loading concentrations, and system temperatures. The equilibrium datasets fit closely with the Freundlich isotherm model, demonstrating successful multilayer dye attachment onto the hydrophobic surfactant bilayers. Kinetic parameters matched the intra-particle diffusion expressions alongside a pseudo-second-order mechanism, showing that chemisorption reactions controlled the mass transfer rates. Thermodynamic constants showed that the adsorption process was endothermic (delta H° = 18.5 kJ/mol) and caused an increase in system randomness at the solid-solution interface (delta S° = 64.2 J/mol K). Negative values of Gibbs free energy (delta G°) spanning from -1.8 to -4.5 kJ/mol confirmed process spontaneity, positioning SMK as an affordable material for dye wastewater treatment.

Keywords: Kaolinite clay; Surfactant modification; Congo red; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: May 12, 2011; Revised: June 26, 2011; Accepted: July 15, 2011; Published: January 03, 2012.

Citation: Yusuf, A. D., & Ani, T. S. (2012). Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Congo Red onto Modified Kaolinite Clay. International Journal of Chemistry, 3(1), 1–9.

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