Study on the Absorption Mechanism of the Sediment to Phosphorus in Yangtze River Yibin Section

Through laboratory study, the isothermal absorption characteristics and dynamics characteristics of sediment to phosphate in Yangtze River Yibin Section were analysed. The study shows that the absorption curve of sediment is in good compliance with Langmuir and Freundlich isothermal absorption curves, which means that the sediment can absorb the phosphate spontaneously, and the absorption is done by polymolecular layer, for which the maximum theoretical absorption amount is 13.969mg/g, and the empirical constant n>1, which shows the sediment in Yangtze River Yibin Section has great absorption activity. Through analysis of primary and secondary dynamics model, it shows that the absorption of phosphorus is divided into fast absorption and slow absorption period, and the secondary dynamics equation can simulate the process more accurately. Under different sediment and water ratio, the relative error of theoretical equilibrium concentration and experimental equilibrium concentration calculated from the equation is less than 5%.