用悬液Wien效应研究阳离子与土壤粘粒间的能量关系  

ENERGY RELATIONSHIP BETWEEN CATIONS AND SOIL CLAY PARTICLES AS INFERRED FROM THE WIEN EFFECT IN DILUTE SUSPENSIONS

作　　者：王卫[1] 王玉军[2] 李成保[2] 朱浩文[1] 周东美[2] 徐仁扣[2] 周立祥[1] 

机构地区：[1]南京农业大学资源与环境科学学院,南京210095 [2]土壤和农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008

出　　处：《土壤学报》2007年第3期451-457,共7页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(40401030)资助

摘　　要：从能量关系研究土壤带电粘粒与电解质离子间的相互作用一直是土壤化学家希望解决的课题。本文介绍阳离子与带电粘粒间的平均结合自由能和平均吸附自由能的计算公式,并用悬液Wien效应法研究K^＋、NH4^＋、Ca^2＋和Cd^2＋与黄棕壤、棕壤和黑土粘粒间的能量关系。研究结果表明：K^＋和NH4^＋的平均结合自由能范围为6.3～7.1kJ mol^-1,K^＋的结合能稍大于NH4^＋的;Ca^2＋和Cd^2＋的结合能范围为7.2～9.4kJ mol^-1。同一阳离子与不同土壤的结合能顺序如下：黄棕壤〈棕壤〈黑土。它们在同一高场强（如150kV cm^-1）下的平均吸附能ΔGad值：K^＋和NH4^＋在黄棕壤和棕壤粘粒上的很接近,分别为0.9和0.8kJ mol^-1,而在黑土粘粒上,NH4^＋的较K^＋的大0.1kJ mol^-1;Ca^2＋在黄棕壤和黑土上的吸附能较Cd^2＋的分别大0.3和0.6kJ mol^-1;二价阳离子的平均吸附自由能约为一价阳离子的2～2.5倍。Interactions between charged soil clay particles and cations in the field of energy has long been a subject attracting all soil chemists. Efforts are made to introduce equations for calculating mean free binding energy and mean free adsorption energy between cations and charged soil clay particles and the application of Wien effect in dilute suspensions, to the study on energy relationships between cations of K^＋ , NH4^＋ , Ca^2＋, and Cd^2 ＋ and clay particles of yellow-brown soil, brown soil, and black soil. Results show that 1） mean free binding energies between cations of K^＋ , and NH4^＋ and the clay particles are in the range of 6.3 ～ 7.1 kJ mol^-1, and slightly higher with K^＋ than with NH4^＋ ; 2） mean free binding energies between ions of Ca^2＋ , and Cd^2＋ are in the range of 7.2 ～ 9.4 kJ mol^-1. With the same cation, the soils follow the order of yellow-brown soil 〈 brown soil 〈 black soil in binding energy. The mean free adsorption energies, △Gad, of the four cations with the three soils under the same high field strengh, e.g., 150 kV cm^-1, show that the values of K^＋ and NH4^＋ are quite close in yellow-brown soil and brown soil, being 0.9 and 0.8 kJ mol^-1, respectively; but in black soil, the value of NH4^＋ is higher than that of K^＋ by 0.1 kJ mol^-1. The adsorption energies of Ca^2＋ in yellow-brown soil and black soil are 0.3 and 0.6 kJ mol^-1 higher respectively, than that of Cd^2＋ . The adsorotion energies of divalent cations are 1 ～ 1.5 times higher than that of monovalent cations.

关 键 词：悬液Wien效应 阳离子 土壤粘粒 平均结合自由能 平均吸附自由能 

分 类 号：S153.2[农业科学—土壤学]