Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Acid Blue 25 Dye onto Modified Smectite Clay

International Journal of Chemistry | Vol. 8, No. 11, November 2017 | pp. 81–88

DOI: 10.46882/2017/IJC/000110

Article Type: Original Research Paper

Title: Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Acid Blue 25 Dye onto Modified Smectite Clay

Names of Authors: A. D. Yusuf¹, M. A. Al-Dosari²*

Authors’ Affiliations:
¹Department of Industrial Chemistry, Federal University of Technology, Yola, Nigeria.
²Department of Chemistry, Qatar University, Doha, Qatar.

Abstract: The release of highly stable anionic anthraquinone dyes like Acid Blue 25 from textile finishing plants causes significant environmental and toxicity hazards in surface aquatic resources. This study examines the adsorptive uptake performance of a surfactant-modified smectite clay (SMS) prepared via chemical functionalization with hexadecyltrimethylammonium bromide (HDTMA-Br). The structural parameters of raw and modified clays were characterized using X-ray diffraction (XRD) and FT-IR spectroscopy. Adsorption operations were conducted via batch runs, monitoring changes in contact time, 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° = 21.4 kJ/mol) and caused an increase in system randomness at the solid-solution interface (delta S° = 72.5 J/mol K). Negative values of Gibbs free energy (delta G°) spanning from -2.1 to -5.5 kJ/mol across the 298 to 328 K range confirmed process spontaneity, positioning SMS as an affordable material for industrial dye wastewater treatment.

Keywords: Smectite clay; Surfactant modification; Acid blue 25; Adsorption isotherm; Chemisorption; Thermodynamic parameters

Manuscript Timeline: Received: October 02, 2016; Revised: November 15, 2016; Accepted: December 04, 2016; Published: November 09, 2017.

Citation: Yusuf, A. D., & Al-Dosari, M. A. (2017). Thermodynamic Modeling, Desorption Kinetics, and Multilayer Adsorption of Acid Blue 25 Dye onto Modified Smectite Clay. International Journal of Chemistry, 8(11), 81–88.

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