In this study, the adsorption characteristics of cadmium by the natural zeolite have been experimentally investigated in a circular flume. The effect of various parameters, such as initial cadmium and zeolite concentrations has been studied to get enhanced simulations for the natural conditions. The optimum equilibrium time was found to be 2 to 3 hr, which was independent of initial cadmium concentration. The results showed that the cadmium adsorption increased with an increase in the zeolite doses. The adsorption values increase by decreasing the initial cadmium concentration. The results of this study also showed that the absorption rate of zeolite increases from 33.3 to 123.23 mg/kg, but removal percentage of natural zeolite is reduced from 45.45 to 33.6 percent. In addition, with increasing the zeolite concentration from 3 to 20 gr/liter, the absorption rate decreased from 123.23 to 32.5 mg/kg. The results showed that pseudo second order model best described the adsorption rate.
