Removal of Rhodium (III) from Aqueous Solution by Na- and K-Treated Clinoptilolites

Abstract

The clinoptilolite which was modified with sodium and potassium chloride was found to have adsorption capacity for rhodium. To evaluate the adsorption capacity and characteristics, the effects of solution pH, dose of clinoptilolite loading, contact time, temperature, and initial rhodium concentration were investigated in a batch mode. Adsorption was decreased with the increasing temperature for both modified clinoptilolites. The Langmuir and Freundlich adsorption models were used for mathematical description of the adsorption equilibrium. Equilibrium data were fitted to the Langmuir model in the concentrations of 2-60 mg l(-1) at 293 and 313 K. Based on the Langmuir isotherm plots, the maximum adsorption capacity value was calculated to be 0.415 mg g(-1) at 293 K. Various thermodynamic parameters such as a dagger GA degrees, a dagger HA degrees, and a dagger SA degrees were evaluated with results indicating that this system was an exothermic spontaneous reaction and kinetically suited to the pseudo-second-order model.