我国东部河网地区土壤与河道底泥对磷的吸附特性比较研究

通过等温吸附、动力学吸附和热力学吸附模拟试验对我国东部河网地区稻田土壤与河道底泥对P的吸附特性进行了比较研究.结果表明:Langmuir方程对稻田土壤与河道底泥对P的等温吸附拟合程度最好,Freundlich方程次之,Temkin方程最差.稻田土壤和河道底泥的吸附常数K值分别为0.82和0.95,表明河道底泥吸附P的能力要强于稻田土壤.无论是稻田土壤还是河道底泥,对P的吸附都存在着快吸附和慢吸附两个过程.稻田土壤与河道底泥对水体P的吸附主要发生在0 ～ 2 h之内,2 h以后基本达到了一种慢吸附直至平衡过程.在相同的时间段内,河道底泥对P的吸附速率比稻田土壤大,Elovich方程为描述P动力吸附的最优模型.P的热力学吸附结果表明,温度对河道底泥和稻田土壤吸附P都有明显的影响,但比较而言,温度对河道底泥吸附P的影响较大,也就是说,河道底泥更容易发生对P的吸附反应.

Characteristics of Phosphorus Adsorption on Paddy Soil and River Sediment in East China

Characteristics of phosphorus adsorption on paddy soil and river sediment in East China were investigated through isothermal, dynamic and thermodynamic batch experiments. Results showed that Langmuir equation was optimal to fit the isothermal adsorption of phosphorus on paddy soil and river sediment. K values, the adsorption constants of phosphorus on paddy soil and river sediment, were 0.82 and 0.95 respectively, indicting that the river sediment had a higher potential in phosphorus adsorption than the paddy soil. There were two processes of phosphorus adsorption on both the paddy soil and river sediment, i.e., a slow and a rapid reaction process. The adsorption of phosphorus almost finished rapidly within 2 hrs on the paddy soil and river sediment, then became slow till to equilibrium. Within the same period, the adsorption rate of the river sediment was higher than that of the paddy soil. Elovich equation was optimal model to describe phosphorus adsorption dynamics. According to the results of thermodynamics, the temperature exerted a great effect on river sediment, and phosphorus adsorption reaction was more easily on the river sediment than the paddy soil.