Phosphorus adsorption of some clay minerals and soils

Phosphorus adsorption of kaolinite,montmorillonite,attapulgite,vermiculite and zeolite and their affecting factors were studied through experiment on isotherm P adsorption and post-saturation-adsorption P release.Results show that vermiculite is theoretically the highest in P saturation adsorption capacity,being 3 473 mg·kg~(-1) and followed by attapulgite,yellow cinnamon soil,montmorillonite and Xiashu loess,zeolite and kaolinite.The last is the lowest in theoretic P saturation adsorption capacity,lingering at 554 mg·kg~(-1).The P adsorption capacity of these clay minerals and soils was mainly influenced by their contents of reactive Ca,Fe and Al,but it was not much affected by soil pH value,CEC and specific surface of the clay minerals and soils,because the main mechanism of the adsorption is chemical sorption.Meanwhile another experiment on desorption of phosphorus from these clay minerals and soils saturated with phosphorus was also conducted.Results show that P release from the clay minerals and soils after P saturation adsorption was very limited.