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用平衡水气压法测定几种土壤对气态水的吸附量,进而推求吸附气态水的热力学函数。结果表明,土壤吸附气态水的机制类似BET多分子吸附。供试土样的实验最大平衡吸附量顺序:表土为黄泥巴>盐碱土>红油土>垆土>黑垆土;同一土壤不同层次为粘化层>表层。实验最大平衡吸附量与土壤阳离子代换量、比表面和物理性粘粒含量呈正相关。在含水量为5.3%时,几种土壤相对偏摩尔焓值顺序:表土为黑垆土>垆土>盐碱土>红油土;同一种土壤(黑垆土),表层>粘化层。相对偏摩尔自由能和熵的大小顺序基本与相对偏摩尔焓相同。土壤吸附气态水的相对偏摩尔焓、自由能、熵与土壤比表面呈反相关,相对偏摩尔焓与土壤阳离子代换量亦成反相关,并皆与温度有密切关系。
The equilibrium water pressure method was used to determine the adsorption capacity of several soils to gaseous water, and then the thermodynamic function of adsorbed gaseous water was deduced. The results show that the mechanism of adsorption of gaseous water on soil is similar to BET multi-molecular adsorption. The maximum amount of equilibrium adsorption for the tested soil samples was as follows: the topsoil was yellow mud> saline-alkali soil> red oil soil> clay soil> black mulch soil; different layers of the same soil were the viscous layer> surface layer. The maximum amount of equilibrium adsorption was positively correlated with soil cation exchange capacity, specific surface area and physical clay content. When the water content is 5.3%, the relative partial molar enthalpy order of several soils is as follows: black soil topsoil> clay soil> saline soil> red oil soil; same soil (black soil), surface layer> sticky layer. The relative partial molar free energy and entropy order of magnitude is basically the same as the relative partial molar enthalpy. The relative partial molar enthalpy, free energy and entropy of soil-adsorbed gaseous water are inversely correlated with the specific surface area of the soil. The relative partial molar enthalpy is also inversely correlated with the soil cation exchange capacity, and both are closely related to temperature.