Diffusion of Chloride Ions in Soils：II.Kinetic and Ther—modynamic Characteristics
摘要
The amounts of chloride ions diffused in four soils of different textures at the same water content under different temperature and at varied time were measured by the diffusion cell method using ^36Cl-labelled CaCl2 solution,Five kinetic models were used to fit the dynamic process of the diffusion of chloride ions in the soils ,It was found that Elovich equation or power function equation was the best model to describe the process .The pseudothermodynamic parameters,i.e.the net reaction energy,the activation entropy, activation enthalpy and activation free energy of the diffusion,were dervied from the absolute reaction-rate theory.The results showed that these parameters decreased in the order of loessal soil>black lu soil> lou soil> yellow cinnamon soil,which indicated that the force an the heat-energy barrier to be overcome for diffusion decreased ,the diffusion rate increased and the disorder of the soil-solution-ion system due to diffusion decreased successively with the texture becoming heavier in the four soils.