Removal of Ni(II) ions from aqueous solutions with Siirt Kocpinar mixed type clay investigation of isotherm, thermodynamic and kinetic parameters

Abstract

This study used mixed-type clay as an adsorbent to remove Ni(II) ions from the aqueous solution. Crystallographic analyses were performed for crystalloplotic identification. Concentration, temperature, amount of adsorbent, and thermodynamic parameters, which are among the parameters affecting the adsorption, were examined. The obtained data were applied to the Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich adsorption isotherms. It was determined that the data fit the Langmuir adsorption isotherm model the most. The adsorption capacities were determined as 24.81, 29.85 and 58.14 mg/g Ni on clay at 298, 308, and 313 K, respectively. Kinetics data were obeyed to pseudo-second-order. Thermodynamic data (for 298, 308, and 318 K) were calculated as Delta G = -18.569, -20.879, -23.189 kJ/mol, Delta H = 22.60 kJ/mol and Delta S = 0.141 kJ/mol.K, respectively. The Delta H and Delta S values can be obtained directly from the slope and shift of the Gibbs plot presented in this study which is not seen before in the literature. The clay used in the study was chosen due to its low cost and easy acquisition, and as a result of the analysis, it was determined that it could be used as an adsorbent with moderate efficiency in removing Ni(II) ions from water.