African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1064

Full Length Research Paper

Isotherms, kinetic and thermodynamic studies of methylene blue adsorption on chitosan flakes derived from African giant snail shell

Olaosebikan Abidoye Olafadehan
  • Olaosebikan Abidoye Olafadehan
  • Department of Chemical and Petroleum Engineering, University of Lagos, Akoka-Yaba, Lagos 101017, Nigeria.
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Victor Ehigimetor Bello
  • Victor Ehigimetor Bello
  • Department of Chemical and Petroleum Engineering, University of Lagos, Akoka-Yaba, Lagos 101017, Nigeria.
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Kehinde Olawale Amoo
  • Kehinde Olawale Amoo
  • Department of Chemical Engineering, Lagos State University, Epe, Lagos State, Nigeria.
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Adebukola Morufat Bello
  • Adebukola Morufat Bello
  • Department of Chemical and Petroleum Engineering, University of Lagos, Akoka-Yaba, Lagos 101017, Nigeria.
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  •  Received: 06 September 2021
  •  Accepted: 07 January 2022
  •  Published: 31 January 2022

Abstract

In the present study, modeling of 19 adsorption isotherms, 8 kinetic models and thermodynamics of methylene blue (MB) adsorption on chitosan flakes synthesized using Archachatina marginata shell wastes was investigated in a batch mode. The operational parameters’ effects on the MB adsorption were studied. The model parameters were statistically analyzed using 10 error functions. The choices of the best fitted adsorption and kinetic models were based on the comparison of the sum of normalized error (SNE) and two statistical tools of information-based criteria. The 5-p Fritz-Schlüender isotherm best fitted the experimental adsorption data of MB on chitosan flakes based on SNE whereby maximum adsorption capacity, , of 143.6660 mg/g was obtained.  The adsorption rate of MB on chitosan flakes was kinetically described by pseudo second-order model at all initial concentrations of MB investigated, with film diffusion being the rate-controlling step and the adsorption process chemisorption-influenced. The calculated thermodynamic parameters, = 4.23 kJ/mol, = 0.4563 kJ/(mol K), negative  values revealed that the adsorption of MB onto chitosan flakes was physical, endothermic, spontaneous, energetically favorable and exergonic.  The reaction mechanism of the adsorption of MB onto chitosan flakes was proposed taking cognizance of the electrostatic force of attraction between the negatively charged surface of the chitosan (biosorbent) and the positively charged MB.

 

Key words: chitosan, dye adsorption, isotherm, kinetics, thermodynamics, information-based criteria.