气体、溶液中的非电解质和电解质在多孔颗粒内扩散的对比研究

Comparative Study on the Effective Diffusion of Gases, Non-electrolytes and Electrolytes in Porous Particle

实验测量了气体、溶液中的非电解质以及电解质三类性质相差较大的体系在相同的多孔颗粒内(孔隙率0.234～0.632)的有效扩散系数,并计算出曲折因子.探讨了由D_(?)=D_oε/τ定义的曲折因子对孔隙结构和扩散组分特性的依赖关系.

A comparative study was carried out on the diffusion behavior of different diffusing species, including gases, non-electrolytes and electrolytes, in porous particles prepared in the laboratory and believed to have the same pore structure. The effective diffusivities of different gas pairs, hydrogen in nitrogen or in argon, and nitrogen or argon in hydrogen, were measured by the dynamic pulse response method. From the values of effective diffusivities, tortuosity factors were calculated and compared for different diffusion species in the pellets (with porosities from 0.234 to 0.632). The tortuosity factors for gas diffusion are only slightly dependent on the properties of diffusion species, while strongly dependent on the porosities of the pellets. The effective diffusivities of potassium chloride or lithium chloride in water and benzene in ethanol were also measured in a well-stirred reactor. The results clearly demonstrate that the tortuosity factors of the diffusion of a binary electrolyte are not so markedly influenced by the pellet porosity as compared with gas diffusion. The tortuosity factors for the diffusion of a non-electrolyte differ from those for diffusion of a binary electrolyte in water in the range of 20% to 60%.