Influence of silicon on the adsorption characteristics of Cadmium in soils

Adsorption isotherm experiments were conducted to investigate the effect of silicon on the adsorption of cadmium in two paddy soils. The pH value of media was adjusted to neutral to eliminate the effect of silicon addition on soil pH. The results showed that when adding the same amount silicon, the adsorption amount of cadmium in soil with low pH was lower than the soil with high pH value. While cadmium added at 0～50 mg·L-1, the adsorption of cadmium in two soils conformed to the Freundlich adsorption isotherm best. With increasing of the additive silicon at the range of 0～120 mg·L-1,the adsorption quantity of cadmium had different degrees of decease. Hence, the idea that additive silicon decreases the effect of cadmium in soil and relieves the poison for plant is not the adsorption of cadmium in soil, and other mechanisms may exist, which need to be developed.