离子交换吸附平衡及其动力学兼论海水提铀机理

THEORY OF KINETICS AND EQUILIBRIUM OF ION EXCHANGEADSORPTION AND MECHANISM OF EXTRACTING URANIUM FROM SEA-WATER WITH TITANIC GEL

本文通过质量作用定律导出的离子交换吸附等温式,可概括经验的、半经验的Gapon公式、Sips公式、Langmuir公式和Freundlich公式。采用交换吸附是动力学的控制步骤,可导出交换动力学公式。该式得到海水提铀实验的验证;且可解释用于证明“颗粒内扩散或液膜扩散机理”的实验数据;也可解释“颗粒内扩散和液膜扩散联合控制”的实验数据。此外,本文还讨论了钛胶海水提铀的机理,为平衡吸铀量的计算提供了理论和方法。

An isothermal equation for ion exchange-adsorption is derived by mass action law. The equation can be used to sum up empirical and semiempirical formnlas of exchangeadsorption, such as Gapon Equation, Sips Formula, Langmuir Equation and Freundlich Formula.In this paper, by adopting the ion exchange reaction to act as the determining step of the ion exchange adsorption kinetics, an exchange-adsorption kinetics equation is derived. It is verified by the results of a series of experiments in which uranium is extracted form enriched sea-water and natural sea-water with hydrous titanium oxide (titanic gel). This equation can be used to explain not only the results of tests which have been applied to prove fast intraparticle diffusion or liquid film deffusion mechanism, but also test data which can be explained by the co-controlling fast intraparticle and liquid film diffision, and the kinetic data which can not be clarified by diffusion mechanism.It is proposed that the mechanism of the exchange adsorption of uranium from sea-water with titanic gel is a cationic exchange reaction as follows: ≡Ti—OH + UO_2OH^+≒≡Ti—OUO_2OH + H^+ A method for calculating the quantity of exchange-adsorption at equilibrium is also given.