人工合成P型沸石对NH_4^+交换特性研究

Study on the Properties of NH_4^+ Ions Exchange of Artificial Synthetic Zeolite P

应用由粉煤灰合成的P型沸石研究对NH_4^+交换的热力学和动力学特性。结果表明,P型沸石阳离子交换总量为264meq/100g,在其整个阳离子组成范围内对进入的NH_4^+具有高的选择交换性,该交换过程能自发沿着正方向进行,随着温度的增高,其交换能力也增强。Na^+=NH_4^+交换过程具有较优越的动力学特性,在16℃和32℃时,P型沸石中NH_4^+自扩散系数分别为7.14×10^(-10)和1.12×10^(-9)cm^2·s^(-1);活化能为20.74kJ·mol^(-1);活化熵分别为-88.26和-88.71J·(mol·°K)^(-1);自由能分别为43.85和45.26kJ·mol^(-1)。

The zeolite P which was synthesised artificially from fly ash has been used for studying the ther-modynamic and kinetic properties of NH4+ ion exchange. The results showed that the total cation exchange capacity of zeolite P was about 264 meq/100g. It possessed of great selectivity for entering NH4+ ions into the range of its full cation concentration. This process would be gone on spontaneously along positive direction, and its selectivity would be enhanced with increasing the temperature, The superior kinetic properties were exhibited in the Na+ NH4+ exchange reaction. At 16℃ and 32℃, the diffusion coefficients of NH4+ ion in zeolite P were 7.14× 10-10 and 1.12×10-9cm2 · s-1 respectively; the energy of activation was 20.74kJ ·mol-1; the entropies of activation were -88.26 and -88.71 J·(mol-1 ·°K-1)respectively; Gibbs energies were 43.85 and 45.26kJ·-mol-1 respectively.