黄土性土壤在连续液流条件下吸附、解吸磷酸根的动力学研究

采用连续液流法研究了黄土性土壤吸附,解吸磷酸根的动力学性质。结果表明：（１）供试土壤对磷酸根的吸附,解吸扫速率可分为快,中,慢三种反应类型;（２）描述吸附,解吸反应的最优模型均为Ｅｌｏｖｉｃｈ方程,最差模型分别为一级反应方程及双常数方程,拟合差的模型对反应速率变化“敏感”,可用于反应类型划分和机理研究;（３）粘粒含量及代换量对吸附速率有著影响,游离铁对吸附速率,ＣａＣＯ３对较低温度下的吸附及较高温

KINETICS OF PHOSPHATE ADSORPTION-DESORPTION OF LESSIAL SOILS UNDER CONTINUOUS LIQUID CURRENT

Kinetics characteristics of phosphate adsorption-desorption by Loessial soils were studied under the conditions of continuous liquid current. Phosphate was adsorbed and desorbed at different rates. According to the rate, the reaction of adsorbing-desorbing could be divided into three types: fast, middle and slow reactions. Elovich equation was the best model to decribe the adsorption and desorption of phosphate, while the first-order and parabolic diffusion equations were the worst; but the worst models were "sensitive" to the changes of reaction rate and could be used to classify reaction type and to study the reaction meachanism. The rates of adsorption and desorption were closely related to the soil clay and CEC. The influences of free Fe₂O₃ on adsorbing rate and CaCO₃ on adsorbing rate under lower temperature and desorbing rate under higher temperature were siginficant. The rapiddly available phosphorus was an important factor to control the desorption rate. The rate of phosphate adsorption was significantly influenced by temperature, but the effect of temperature on the desorption rate was not significant. The adsorption and desorption rates, capacit, of phosphate and reaction time varied with soil types and horizons.