溶剂萃取法是工业上应用最广泛的分离纯化稀土元素的方法。稀土元素的物理化学性质极其相近，使得稀土元素的分离十分困难，特别是相邻稀土元素的分离更加困难，目前采用溶剂萃取法获得单一的稀土产品需要成百上千的萃取级数。怎样提高稀土元素之间的分离系数一直备受研究者的关注。热力学平衡态分离稀土元素的研究已取得了很多的进展，一定程度上改善了稀土分离的工艺。一些研究报道了某些萃取体系中动力学分离系数远远大于热力学平衡态分离系数的现象，而目前关于动力学萃取分离的实验和理论的研究均比较少，因此研究动力学方法分离稀土元素具有十分重要的意义。本文以相邻稀土元素中分离十分困难的Pr(III)、Nd(III)为分离目标，研究了萃取剂[A336][NO3]萃取Pr(III)、Nd(III)的动力学，提出了动力学推拉体系[A336][NO3]-DTPA分离Pr(III)、Nd(III)的新工艺。具体研究内容和结果如下：采用单液滴法研究了[A336][NO3]萃取Pr(III)、Nd(III)的动力学。通过考察柱长，毛细管孔径，稀土离子浓度，盐析剂浓度，酸度，萃取剂浓度对初始萃取速率的影响，获取[A336][NO3]萃取Pr(III)、(III)的速率方程，同时考察了温度对初始萃取速率的影响，得到萃取反应的活化能，活化熵，活化焓，并且推导萃取反应机理。由[A336][NO3]萃取Pr(III)、(III)的速率方程得出，[A336][NO3]萃取Pr(III)的反应速率常数是萃取Nd(III)的反应速率常数的2.04倍。温度实验结果表明，[A336][NO3]萃取Pr(III)、Nd(III)的表观活化能分别为9.145 kJ/mol和11.604 kJ/mol，[A336][NO3]对Pr(III)、Nd(III)的萃取过程均为扩散控制。[A336][NO3]萃取Pr(III)、Nd(III)的初始速率均随毛细管孔径的增加而减小，萃取反应发生在液液界面，而不是体相。[A336][NO3]萃取Pr(III)、Nd(III)的活化焓分别为6.573 kJ/mol和9.055 kJ/mol，[A336][NO3]对Pr(III)、Nd(III)的萃取反应为快反应。[A336][NO3]萃取Pr(III)、Nd(III)的活化熵分别为-833.61 J/(mol?K)和-836.25 J/(mol?K)，[A336][NO3]对Pr(III)、Nd(III)的萃取反应均服从SN2机制，生成的萃合物的结构比萃取剂分子更加有序。基于萃取剂[A336][NO3]萃取Pr(III)的速率快于萃取Nd(III)，水溶性络合剂DTPA络合Nd(III)的速率快于络合Pr(III)，提出了动力学推拉体系分离Pr(III)、Nd(III)的柱萃取工艺。考察了络合剂加入方式，络合剂pH，络合剂加入量，盐析剂浓度，水相Pr(III)、Nd(III)初始摩尔比，水相料液的pH，萃取剂浓度对分离系数的影响。实验结果表明，当[A336][NO3]以液滴的形式从萃取柱的底端喷出进入水相时，即萃取初始时，将DTPA的水溶液从萃取柱的底部快速注入，发现Pr(III)、Nd(III)的分离系数随着萃取时间的增加而明显增大。优化萃取条件后，Pr(III)、Nd(III)的分离系数的最大值达到21.7，远大于该萃取体系平衡态分离系数5.8。达到最大分离系数对应的萃取时间是290 min，有机相与水相的相比O/W为20:1。DTPA的加入方式不同，Pr(III)、Nd(III)的分离系数有显著的差异，表明DTPA与Pr(III)、Nd(III)络合速率的差异对于动力学分离有重要作用。改变络合剂pH，络合剂加入量，水相料液的pH，DTPA络合Pr(III)、Nd(III)的速率发生改变，从而影响[A336][NO3]萃取Pr(III)、Nd(III)的速率。DTPA对Pr(III)、Nd(III)络合速率的快慢与[A336][NO3]萃取Pr(III)、Nd(III)的速率匹配时，动力学推拉效应明显，可以得到较高的分离系数。采用气泡油膜作为有机相的载体强化萃取动力学推拉体系分离Pr(III)、Nd(III)的工艺。考察了络合剂pH，络合剂加入量，盐析剂浓度，水相Pr(III)、Nd(III)初始摩尔比，水相料液的pH，萃取剂浓度对分离系数的影响。实验结果表明，水相Pr(III)、Nd(III)初始摩尔比为1:4，DTPA的pH为5.0，DTPA的浓度为0.0223 mol/L, LiNO3的浓度为4 mol/L，水相料液的pH为3.0，[A336][NO3]的浓度为0.4 mol/L时，分离系数的最大值达到11.5。达到最大分离系数对应的萃取时间是160 min，有机相与水相的相比O/W为1:2。与液滴形式对比，气泡油膜作为有机相的载体大大降低了萃取时间和有机相与水相的相比，提高了萃取效率，降低了有机相的消耗量。建立了[A336][NO3]-DTPA体系动力学分离Pr(III)、Nd(III)的数学模型。发现水相中未被DTPA络合的Pr(III)、Nd(III)的浓度比对动力学推拉效应有十分重要的作用。水相中未被DTPA络合的Pr(III)、Nd(III)的浓度比大于1:0.925时，不利于动力学推拉分离Pr(III)、Nd(III)；水相中未被DTPA络合的Pr(III)、Nd(III)的浓度比在1:2.04到1:0.925之间，有利于动力学推拉分离Pr(III)、Nd(III)。;Separation and purification of rare earths by solvent extraction have becoming one of the most important techniques in industrials. However, the practical industrial processes are very difficult to be operated due to the extreme similarity in physical-chemical properties of rare earths, especially for adjacent rare earths. To achieve a pure rare earth chemical, several hundreds or even thousands of stages of traditional mixer-settlers are required. How to improve the separation factor of rare earths gains great attention. Many progresses have been made in separation of rare earths at equilibrium extraction, which make some improvement to the rare earth separation process. However, kinetic separation of rare earths by solvent extraction can obtain a more satisfying separation than equilibrium extraction in some studies. So far, the researches on kinetic separation data and mechanism are few. Therefore, it is important to investigate the extraction separation of rare earth by kinetic methods. Pr(III) and Nd(III) are the most difficult separated elements in light rare earths. In our work, the extraction kinetics of Pr(III) and Nd(III) by [A336][NO3] was investigated. Kinetic “push and pull” system of [A336][NO3]-DTPA for Pr(III) and Nd(III) separation was investigated. The main research contents and results are shown as follows:Extraction kinetics of Pr(III) and Nd(III) by [A336][NO3] in nitrate medium were investigated by single drop technique. The dependence of Pr(III) and Nd(III) extraction rates on column height, nozzle diameter, concentrations of Pr(III) and Nd(III) in the aqueous phase, concentration of salting-out agent, pH, concentration of [A336][NO3] were studied. The rate equations of [A336][NO3] extracting Pr(III) and Nd(III) were obtained. The apparent activation energy, activation enthalpy, activation entropy were calculated by temperature experiments and the extraction mechanism was deduced. The rate constant of [A336][NO3] extracting Pr(III) was double than that of [A336][NO3] extracting Nd(III). The apparent activation energy of [A336][NO3] extracting Pr(III) and Nd(III) were 9.145 kJ/mol and 11.604 kJ/mol，respectively, which indicated that the extraction processes of Pr(III) and Nd(III) by [A336][NO3] were both diffusion controlled. The extraction rates of Pr(III) and Nd(III) by [A336][NO3] decreased with increasing the nozzle diameters, which suggested that the extraction reactions were occurred at the liquid-liquid interface. The activation enthalpy of [A336][NO3] extracting Pr(III) and Nd(III) were 6.573 kJ/mol and 9.055 kJ/mol，which indicated that the extraction reactions were fast reactions. The activation entropy of [A336][NO3] extracting Pr(III) and Nd(III) were -833.61 J/(mol?K) and -836.25 J/(mol?K)，which indicated that the extraction reactions obeyed to SN2 mechanism and the structures of the extracted species were more ordered than the extractant molecules.As the rate of [A336][NO3] extracting Pr(III) was faster than that of Nd(III), and the rate of DTPA complexing with Nd(III) was faster than that of Pr(III), we presented a kinetic “push and pull” system to separate Pr(III) and Nd(III) in a column extractor. The effects of the adding way of DTPA, the pH of DTPA, the adding amount of DTPA, the concentration of LiNO3, the initial mole ratio of Pr(III) to Nd(III) in the aqueous phase, the pH of the aqueous phase, the concentration of [A336][NO3] on separation factor of Pr(III) to Nd(III) were investigated. As [A336][NO3] was continuously pumped into the column extractor in the form of dispersed oil droplets and at the same time DTPA was injected into the aqueous feed solution when the extraction was just started, the separation factor of Pr(III) to Nd(III) could achieve 21.7, nevertheless the separation factor of this extraction system in extraction equilibrium was 5.8. The extraction time corresponding to the maximum separation factor was 290 min, and the phase ratio (O/W) was 20:1. The different adding ways of DTPA had an obvious effect on separation factor of Pr(III) and Nd(III), which indicated that the difference in the rates of DTPA complexing with Pr(III) and Nd(III) played a crucial role in enhancing the kinetic separation of Pr(III) and Nd(III) by [A336][NO3]. Varying the pH of DTPA, the adding amount of DTPA and the pH of the aqueous phase affected the rates of DTPA complexing with Pr(III) and Nd(III), which indirectly affected the rates of [A336][NO3] extracting Pr(III) and Nd(III). The kinetic “push and pull” effect was obvious as the rates of DTPA complexing with Pr(III) and Nd(III) matched with the rates of [A336][NO3] extracting Pr(III) and Nd(III).Organic phase added into the extraction column in the form of oil bubbles can improve the kinetic separation process. The effects of the pH of DTPA, the adding amount of DTPA, the concentration of LiNO3, the initial mole ratio of Pr(III) to Nd(III) in the aqueous phase, the pH of the aqueous phase, the concentration of [A336][NO3] on kinetic separation of Pr(III) and Nd(III) were investigated. As the initial mole ratio of Pr(III) to Nd(III) was 1:4, the pH of DTPA was 5.0, the concentration of DTPA was 0.0223 mol/L, the concentration of LiNO3 was 4 mol/L, the pH of the aqueous phase was 3.0, the concentration of [A336][NO3] was 0.4 mol/L, the maximum separation factor can reach 11.5. The extraction time corresponding to the maximum separation factor was 160 min, and the phase ratio (O/W) was 1:2. Contrasted to oil droplets, oil bubbles as the organic phase carrier greatly reduced the extraction time and the phase ratio of O/W.The mathematical model of [A336][NO3]-DTPA system was built. The concentration ratio of uncomplexed Pr(III) and Nd(III) in the aqueous phase was crucial to enhance the kinetic “push and pull” effect. As the concentration ratio of uncomplexed Pr(III) and Nd(III) was above 1:0.925, it had a disadvantage impact on the kinetic separation of Pr(III) and Nd(III). As the concentration ratio of uncomplexed Pr(III) and Nd(III) was in the range from 1:2.04 to 1:0.925, it was in favor of kinetic separation of Pr(III) and Nd(III).