| It is well known that rare earth elements was used widely in now sociaty, covering many fields such as the military, the aerospace, photo electromagnetic functional materials, and the metallurgy, the chemical industry, the role that it plays is more and more important. the production requirement for single high purity rare earths is becoming higher, at the same time, it gets more and more attention and concern. The source of the rare earth elements mainly has two aspects: separation and purification of the original rare earth ore and reprocessing of spent nuclear fuel. Because of the same structure and the physical and chemical properties comparies with all kinds rare earth elements, how to separating and purifing each element from original rare earth ore and spent nuclear fuel is very difficult, so these has becoming the bottleneck for the development of its application.Solvent extraction as one of the most commonly used purification method, it has been used wildely in a number of high, refined, sharp field. A larger research progress has been madefor various elements' s separation through different thermodynamics extraction conditions and influencing factors, but a phenomenon is sxist that the influence of dynamics separation factors is strong than thermodynamic equilibrium separation factors in manys, so there is a great significance for the study of extraction process and theoretical research to doing extraction kinetics experiments, at the same time, there is a very important practical significance for the separation and purification of rare earth elements in the modern industrial production.In this paper, a variety of devices related to the experiment are been designed and producted, at the same time, the interface properties of TODGA/HNO3/H2 O system and TODGA/HNO3/La system were studied, we also investigated the extraction performance of the TODGA/HNO3/RE system and the extraction dynamics of the TODGA/HNO3/RE system, includes the following aspects mainly:(1) N,N,N',N'-tetraoctyl diglycolamide(TODGA) was synthesized, the product was analysed by FTIR, HPLC,1H-NMR that up to the standard;(2) The drop volume device, the removable constant interface extraction cell and new dynamics research device were designed and made, then text its accuracy and repeatability that up to the standard of experimental use;(3) The interface properties of TODGA/HNO3/H2 O system were studied, through investigating the influence of the droplet formation time, acidity, extractant concentration, diluents, ionic strength, and temperature on the interfacial properties by the drop volume method, obtained several related conclusions: The existence of the extractant decreases the interfacial tension of the system as a surfactant; The droplet formation balance time for different systems were determined; Compared the impact of different polarity diluents on the system interface properties; Because of the protonation effect for TODGA, the interfacial activity enhanced with the increasing of HNO3 concentration; The effect of the temperature on the thermal motion of interface molecular, solubility and the combining ability between surfactant and diluents moleculars;(4) The interface properties of TODGA/HNO3/La3+ system were studied, through investigating the influence of the droplet formation time, concentration of different metal ions, acidity, extractant concentration, diluents, ionic strength, and temperature on by the drop volume method, obtained several related conclusions: The droplet formation balance time for TODGA/La3+ system was determined; The effect of extractant concentration and the rare earth ion concentration on the interfacial properties have been investigated, analysised the combining forms and ability for them combined with the thermodynamic study; At the same time, because of the protonation effect for TODGA, the interfacial activity enhanced with the increasing of HNO3 concentration; The effect of the temperature on the thermal motion of interface molecular, solubility and the combining ability between surfactant and diluents molecular for TODGA/La3+ system; With the ionic strength increasing, the interface concentration of extractant reducing, improving the extraction ability for the rare earth ions;(5) The thermodynamic extraction properties and mechanism of TODGA for lanthanides were studied in nitric acid system, through investigating the influence of the extractant concentration, nitric acidconcentration, temperature and diluents on the extraction performance, we deduced the corresponding coordination mechanism, and the molecular structure of the compound, distinguished thar these extraction ractions are exothermic processthrough temperature affect, and the extraction equilibrium constant and thermodynamic function values for these extraction reaction process have been calculated;(6) The extraction kinetics mechanism of TODGA for lanthanides have been investigated in nitric acid system by constant interfacial cell, the extraction process was been controlled by diffusion and chemical reaction through analyzing the effect of stirring speed and interface area on the extraction rate, and finaly obtained the initial extraction rate equation and the apparent activation energy for these extraction system.(7) Combined the interface study, extracting thermodynamics and kinetics, we found that the extraction kinetics mechanism of TODGA for lanthanides is diffusion and chemical reaction controlled process, as increasing the TODGA concentration, solution acidity, the aggregation concentration of TODGA at the interface will umprove, speed up the extraction reaction, improving both the initial extraction rate and the final extraction performance; Elevating temperature is good for the initial extraction rate but does not favor the extraction performance finally. |
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