Experimental study of calcium carbonate role in removal, advection and dispersion of cadmium

In this research, the effect of calcium carbonate, existing in natural environments, on removal, advection and dispersion of cadmium using batch reactor experiments, is studied. The results showed that 99.2% of Cadmium with initial concentration of 1.5 ppm will be removed by CaCo3 with concentration of 330 ppm. Regarding to high ability of CaCo3 in cadmium sorption and the existence of CaCo3 in soils and waters, one can conclude that CaCo3 has a great influence on self purification of natural environments and it must be considered in heavy metal transport transformation modeling. Firstly, by increasing salinity in the range of natural condition, sorption will decreased very fast but after the salinity of 2500 S/cm, the amount of this reduction will decrease. At last, the amount of sorption could be decreased by 50%. Investigation of Langmuir and Freundlich isotherms showed that the governing isotherm for cadmium sorption to CaCo3 on the basis of current data is Freundlich. Furthermore, comparing the linear and nonlinear methods in estimating Freundlich parameters show that the non linear sum of square of errors 0.3 of linear method. So it is better to use non linear method in estimation of parameters.