Abstract
The present work investigates the performance of Cristal-RightTM CR100 zeolite based on the equilibrium and thermodynamics
water softening process. The commercial zeolite was characterized by scanning electron microscopy combined with energy
dispersive X-ray spectroscopy and FT-IR spectroscopy. The equilibrium performances of zeolite were evaluated by the sorption
capacity of calcium cations from calcium chloride solutions varying the calcium concentrations corresponding to moderate, hard
and very hard waters. Experiments were carried in batch mode out as a function of temperature (278, 298, 318 and 338 K) and in
fixed optimum conditions for soption process (pH, zeolite dose and contact time). Equilibrium sorption data were analysed using
Langmuir, Freundlich and Dubinin-Radushkevich isotherm models to obtain the characteristic parameters of each model.
Sorption equilibrium data fitted very well to the Langmuir model that confirmed the monolayer sorption with high correlation
coefficients. According to the evaluation using the Langmuir isotherm, the maximum sorption capacities of calcium cations onto
Cristal-RightTM CR100 zeolite were 31.45 mg/g for 298 K. The thermodynamic parameters values indicate the spontaneous and
endothermic nature of the sorption process by ambient temperature. The sorption energy fell in the range of physisorption.