论文部分内容阅读
研究了我国典型３种可变电荷土壤和４种恒电荷土壤在陪伴阳离子分别为Ｋ十、Ｎａ十、Ｃａ２＋时和１ｍｍｏｌＬ－１ＫＣ１、Ｋ２ＳＯ４支持电解质中ＮＯ３－的吸附。结果表明，ＮＯ３－吸附量随ｐＨ的增加而减小。在添加相同浓度ＮＯ３－时，３种可变电荷土壤对ＮＯ３－的吸附量顺序为Ｃａ（ＮＯ３）２＞ ＫＮＯ３＞ＮａＮＯ３＞ＫＮＯ３十ＫＣＩ＞ＫＮＯ３＋Ｋ２ＳＯ４；在初始ＮＯ３－浓度０．５－５ｍｍｏｌＬ－１的范围内，吸附量随浓度变化的关系符合Ｌａｎｇｍｕｉｒ等温吸附式．由此求出与ＮＯ３－吸附结合能有关的常数（Ｋ）在不同共存离子存在下数值较小且差异不大，因此认为不同陪伴阳离子和不同伴随阴离子对ＮＯ３－吸附的电性机理影响不大，只是改变了土壤表面的正电荷数量从而使吸附量发生变化。４种恒电荷土壤对ＮＯ３－的吸附量通常很小，其中在Ｃａ（ＮＯ３）２介质中较在其他介质中稍大，最大吸附量仅为１．５～ｍｍｏｌ ｋｇ－１左右，约为可变电荷土壤的１／１０，且在浓度较低时常观察到负吸附。
The adsorption of NO3- in the three kinds of variable charge soils and four kinds of constant charge soils in China supported by 1 mmolL-1KC1 and K2SO4 supported electrolytes was studied at K 10, Na 10, Ca 2+, respectively. The results showed that NO3-adsorption decreased with the increase of pH. When NO3- was added at the same concentration, the order of adsorption amount of NO3- in the three kinds of variable charge soils was Ca (NO3) 2> KNO3> NaNO3> KNO3 + KCI> KNO3 + K2SO4; The relationship between the amount of adsorption and the change of concentration conforms to the Langmuir isothermal adsorption equation. Therefore, it is found that the constants (K) associated with the NO3-binding energy are small and have little difference in the presence of different coexistent ions. Therefore, it is considered that the different accompanying cations and different accompanying anions have little effect on the electrical mechanism of NO3- adsorption , Just changed the amount of positive charge on the soil surface so that the amount of adsorption changes. The adsorption capacity of NO3- by four kinds of constant-charge soils is usually very small, which is slightly larger in Ca (NO3) 2 medium than in other media, and the maximum adsorption capacity is only about 1.5 ~ mmol kg-1, which is about Variable charge of soil 1/10, and at low concentrations are often observed negative adsorption.