Adsorption and Desorption Characteristics of Cadmium in Yellow Soil and Limestone Soil

Yellow soil and limestone soil were chosen to study the adsorption and desorption of cadmium in these soil in order to evaluate the ability of migration and environmental risks.The results showed that within the test range,Cd adsorption increased with increasing initial concentration,and limestone soil had a much higher Cd adsorption capacity than yellow soil.While the adsorption rate declined.When the Cd concentration in adsorption equilibrium was 310mg/L,the amount of adsorbed Cd was 2 626mg/kg in limestone soil,but 1 507 mg/kg in yellow soil.While the adsorption rate of Cd in limestone soil and yellow soil was 84.74%and 48.64%respectively.The adsorption isotherm of Cd in the two soils could significantly conform to Freundlich and Henry equations,while Langmuir and Temkin equation was not applicable to describe the isothermal adsorption process of Cd in yellow soil and limestone soil.Within the test range,Cd desorption increased with increasing initial concentration.The desorption rate increased gradually tending to be stable,yellow soil desorption rate of Cd eventually stabilized at25%~30%,limestone soil desorption rate of Cd in 6%~7%.Adsorption capacity of Cd in limestone soil was significantly higher than that in yellow soil,while desorption capacity reversed with higher environmental risk.