多孔离子交换树脂内Eu3+离子的分步扩散

用同位素交换法研究了Eu³⁺离子在D72和D751树脂内的扩散过程.应用分步孔道扩散方程将粒内有效扩散系数D_e分解为孔道扩散系数D_p和固相扩散系数D_g,表明该方程可用于描述多孔树脂内的动力学过程.实验表明,D_e、D_p、D_g均随反应温度的升高而增大.计算了实验条件下的Eu³⁺的自扩散活化能;D72树脂的D_p和D_g对温度的响应比D751树脂大,其D_e、D_p、D_g值亦均大于D751树脂;Eu³⁺在溶液中的自扩散系数D_s＞D_p,说明离子在树脂孔道内的自扩散不能完全等同于其在溶液中的自扩散.

Bidisperse Pore Diffusivity of Eu3+ Ion in Porous Ion Exchange Resins

In this paper the self diffusion of rare earth ion(Eu³⁺ ) in porous ion exchange resins D72 and D751 was studied by isotope exchange reaction. Applying Kataoka's bidisperse pore model, the intraparticle effective diffusivities D_e were resolved into a solid diffusivity D_g and a macropore diffusivity D_p. The results express that Kataoka's equations can illustrate the kinetic process of porous ion exchange resins. The experiments show that D_e, D_p and D_g all increase with the increase of reaction temperature and the self-diffusion activation energy of Eu³⁺ ion under the experimental conditions was calculated; the response D_p and D_g to temperature of D72 resin is more sensitive than that of D751; D_e, D_p and D_g of D751 resin is smaller than that of D72 resin; the diffusivity of Eu³⁺ ion in solution is larger than D_p, which leads to the conclusion that the diffusion of ion in the pore of ion exchange resin can not completely be equal to that in solution.