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本研究目的是了解陕西省的几种土壤吸附和解吸附砷酸盐的速率和过程,以及其吸附能量。Kuo和Lotse导出的双常数速率公式拟合试验资料优于一级、二级、三级反应公式,抛物线扩散和Elovich公式等五个公式。用双常数速率公式(C=k·C_0·t~(1/m))分两段拟合能进一步提高拟合优度。根据Arrhenius公式计算出的吸附活化能是0.70—3.40千卡/克分子。低的活化能表明,供试土壤对砷酸盐的吸附作用是一种完全不同于真溶液条件化学反应的物理学过程。土壤吸附和解吸附砷酸盐的速度和容量受作用时间、温度、溶液∶土壤比率,加入的砷量和浓度,以及土壤特性的影响。粘土的吸附反应常数(k),吸附量比沙壤土大。而沙壤土有高的解吸附反应速度常数(k_(-1)~′),砷酸盐容易被解吸附而释放出来。
The purpose of this study is to understand the rate and process of adsorption and desorption of arsenate in several soils of Shaanxi Province, as well as their adsorption energy. Kuo and Lotse’s bi-constant rate formula fitting test data is superior to the first-order, second-order, third-order reaction formulas, parabolic diffusion and Elovich formula five formulas. Fitting goodness of fit can be further improved by using two constant rate formula (C = k · C_0 · t ~ (1 / m)). The calculated activation energy of adsorption according to the Arrhenius formula is 0.70-3.40 kcal / mol. The low activation energy shows that the adsorption of arsenate on the test soil is a completely different physical process from that of the true solution. The rate and volume of arsenate adsorption and desorption by soils is affected by time of application, temperature, solution: soil ratio, amount and concentration of arsenic added, and soil properties. The adsorption reaction constant of clay (k) is larger than that of sandy loam. The sandy loam soil has a high desorption reaction rate constant (k _ (- 1) ~ ’), arsenate is easily desorbed and released.