ISOTHERM AND KINETIC STUDIES OF Pb(II) ADSORPTION ON RAW AND MODIFIED DIATOMITE BY USING NON-LINEAR REGRESSION METHOD

Gökırmak Söğüt E., Çalışkan Kılıç N.

FRESENIUS ENVIRONMENTAL BULLETIN, vol.26, no.4, pp.2720-2728, 2017 (Journal Indexed in SCI) identifier

  • Publication Type: Article / Article
  • Volume: 26 Issue: 4
  • Publication Date: 2017
  • Title of Journal : FRESENIUS ENVIRONMENTAL BULLETIN
  • Page Numbers: pp.2720-2728
  • Keywords: Non-linear methods, diatomite, modification, kinetic, thermodynamics, GRANULAR ACTIVATED CARBON, AQUEOUS-SOLUTION, METHYLENE-BLUE, LEAD IONS, EQUILIBRIUM, SORPTION, REMOVAL, MODELS, PARAMETERS, CR(VI)

Abstract

This study presents the evaluation of the original diatomite (D-O) and manganese oxide modified (D-mn) diatomite used as adsorbents for Pb (II) removal from aqueous solution. The experimental data were fitted to the non-linear two parameter equation of Langmuir, Freundlich, Dubinin-Radushkevich, and non-linear three parameter equation of Redlich-Peterson, Sips and Toth Isotherms. The correlation coefficient (R-2), standard error (S.E) and Chi-square (x(2)) values were used to select the best theoretical isotherm. Adsorption mechanism of Pb(H) ion onto the D-O was explained by heterogeneous adsorption model while homogenous adsorption model was used to explain the adsorption on D-mn. Also, both adsorbents were observed to comply better with the three-parameter isotherms. Pseudo first-order, pseudo second-order, Elovich and intraparticle diffusion equations were used to describe the adsorption rate of Pb(II). The experimental data were well fitted by the pseudo second-order kinetic model. Thermodynamic parameters such as free energy (Delta G degrees), enthalpy (Delta H degrees) and entropy (Delta S degrees) showed spontaneous and endothermic in nature of adsorption for both of adsorbents.