Sorption And Desorption Characteristics Of Cadmiun In Soil And Group

This experiment applied equilibrium adsorption test, studied the adsorption of black soil, clay and organic-inorganic composite colloidal cadmium(Cd) under the condition of different concentrations of Cd2+ ion, different environments of pH value, different concentrations of exogenous interference Fe3+ ion and Al3+ ion. The results showed that: With the increase of the equilibrium concentration of heavy metals Cd2+,tested soil adsorption of Cd2+ is also accompanied by an increase, specific performance was organic-inorganic complexes > original soil > clay. The size of the amount adsorbed was a positive correlation with the surface area of soil samples for the test, organic matter contained within the unit mass, clay minerals and content of the metal oxides, it was in favor of the adsorption of heavy metals cadmium. Through using Langmuir equation and Freundlich equation to fit the data, the Cd2+ adsorption isotherms of original soil, clay and organic-inorganic composite colloid could be well described by the equation of Freundlich, but the Langmuir equation was not suitable for the description of Cd2+ adsorption isotherms. After the addition of exogenous interfering ions Fe3+,the Cd2+ adsorption of original soil, clay soil and soil organic-inorganic composite colloid was decreasing with the increasing concentrations of Fe3+.specific performance which was the order of adsorption amount was clay>organic-inorganic composite colloids>original soil. After the addition of exogenous interfering ions Al3+. The Cd2+ adsorption of original soil, clay soil and soil organic-inorganic composite colloid was also decreasing with the increasing concentrations of Al3+, specific performance which was the order of adsorption amount was organic-inorganic composite colloids>clay>original soil. The adsorption capacity of original soil, clay and clay composite reached a maximum level at pH 9 and decreased in the order of the original soil >clay composite >clay. In desorption experiment, their desorption capacity decreased with the increase of pH and decreased in the order of clay composite > clay > the original soil. They reached a maximum level at pH 5.pH could affect the adsorption of heavy metal cadmium by affecting the hydrolysis of heavy metals Cd2+, the exchange of Cd2+ and H+, the surface type and surface charge of adsorption of clay composite and cadmium distribution coefficient in the competitive adsorption and desorption system.