Effect of pH, Temperature, and the Role of Ionic Strength on the Adsorption of Mercury(II) by Typical Chinese Soils

A series of batch experiments were conducted to assess the effects of pH, temperature, and ionic strength on mercury adsorption by black and red soils. The results showed that the mercury adsorption increased when the temperature increased from 5 to 15 degrees C for red soil, whereas for black soil, the amount of adsorption was greater at 25 degrees C than at other temperatures. At the same temperature, the adsorption capacity of the black soil was greater than that of the red soil. The adsorption capacity of mercury by soils was not influenced by initial pH, sodium nitrate (NaNO3), or sulfate ion (SO42-). However, the change of chloride ion (Cl-) concentrations had a great effect on mercury adsorption. When the concentration was increased from 10(-3) to 10(-1) mol L-1, the adsorption capacity of mercury on both soils (especially for the red soil) decreased sharply.