Adsorption properties and mechanism of orthophosphate adsorption on soils from the Yeyahu Wetland of Beijing.

In this study, the adsorption kinetics, isothermal adsorption model of orthophosphate (P) on soil from the Yeyahu Wetland of Beijing were investigated. The effects of pH and organic matter content on P adsorption were also analyzed. The results showed that the P adsorption equilibrium time was about five hours and Langmuir cross-shaped isothermal adsorption model well fitted the experiment data. pH had a significant influence on P adsorption. The P adsorption capability achieved the maximum value when the initial pH of the incubation solution was 8. Soil P adsorption capability increased with dissolved organic matters (DOM) increasing. When the concentration of DOM was 100 mg/L, the P adsorption capability reached the highest value and increased by 37.81%, 35.52% and 64.98%, respectively, for soil samples No. 3, 5 and 7 when compared with no DOM experiments. The results of XRD and FT-IR analysis of soil samples before and after P adsorption experiments reveal that kaolinite involved in P adsorption process and it is a key clay component for P adsorption on the Yeyahu Wetland soil of Beijing.