REMOVAL OF CU(II) IONS FROM AQEUOUS ENVIRONMENT VIA NATURAL MIXED CLAY, EXAMINATION OF ISOTERM, KINETIC AND THERMODYNAMIC PARAMETERS

Abstract

Clays are one of the most preferred adsorbents in the removal of heavy metals due to their mechanical stability, inexpensiveness and simplicity for obtainment. Natural clay is primarily characterized via X-Ray diffraction, Fourier transform infrared, Brunauer-Emmett-Teller (BET), (FT-IR) spectroscopy and thermogravimetric (TG) analysis methods. In this study, natural clay was being used to remove Cu(II) ions from the aqueous environment. Concentration, temperature, pH and contact duration - which are the parameters affecting adsorption -were examined. The data were applied to the Freundlich, Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherms and Langmuir adsorption isotherm model was evaluated as the best fit in accordance with the data. Adsorption capacities of 298, 303, 313 K were found to be 30.30, 26.18 and 37.17 mg Cu/g natural clay, respectively.
When the kinetic data were applied to the Lagergren, Ho-McKay, weber- Morris and Elovich models, it was seen that the data mostly complies with the Ho-McKay pseudo second order equation. Also, thermodynamic data such as free energy, enthalpy and entropy were calculated and for CU (II); results of ΔHo= 60.69 k j/mol, ΔSo=0.236 k j/mol and ΔG298= - 8.46 kj/mol, ΔG308= -12.00 kj/mol,
ΔG318= - 14. kj/mol were determined.