African Journal of
Pure and Applied Chemistry

  • Abbreviation: Afr. J. Pure Appl. Chem.
  • Language: English
  • ISSN: 1996-0840
  • DOI: 10.5897/AJPAC
  • Start Year: 2007
  • Published Articles: 354

Full Length Research Paper

Kinetics and thermodynamic studies of adsorption of malachite green onto unmodified and EDTA-modified groundnut husk

Bamgbose Janet Titilayo1*, Bamigbade Akeem Adesina1, Nkiko Mojisola Olubunmi1, Ahmed Sikiru Akinyeye1 and Ikotun Adebomi Ayodeji2  
1Department of Chemistry, University of Agriculture, Abeokuta, Ogun State, Nigeria. 2Department of Chemistry, Bowen University, Iwo, Osun State, Nigeria.
Email: [email protected]

  •  Accepted: 20 November 2012
  •  Published: 31 December 2012

Abstract

A batch experiment was applied to study the adsorption of malachite green from aqueous solution by unmodified and ethylene diamine tetraacetic acid (EDTA)-modified groundnut husk. The effect of initial dye concentration, temperature, contact time and pH on the sorption process was investigated. The Langmuir and Freundlich adsorption isotherms were applied to test the experimental data. The chemically modified groundnut husk agreed well with both the Langmuir and Freundlich models at the temperature below the room temperature (25°C) and above the room temperature. Unmodified groundnut husk showed poor agreement with the isotherm at temperature below the room temperature but fits well into the model at higher temperature. Kinetics of the adsorption with respect to the initial dye concentration and temperature was also investigated. The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to test the kinetic data. Obtained data were fitted properly in the pseudo-second-order kinetic model. The thermodynamic parameters such as change in free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) were also determined and the results obtained confirmed that the sorption process is feasible, spontaneous, and endothermic.

 

Key words: Adsorption capacity, ethylene diamine tetraacetic acid (EDTA)-modified, groundnut husk, diffusion, Kinetic modelling.