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通过斜率分析法研究了P204和TOPO从磷酸体系中液液萃取微量镧的反应机制和热力学,推测出一种可能的反应历程和萃合物结构,得到萃取反应式和反应的平衡常数K=104.502,焓变ΔH=-13.02 kJ.mol-1,自由能ΔG=-25.686 kJ.mol-1,熵变ΔS=0.0425kJ.(mol.K)-1。在液液萃取反应机制研究的基础上,采用液膜萃取法进行磷酸体系中微量镧的富集回收研究,考察了载体P204(2%～10%w/w)和TOPO(1%～10%w/w)、表面活性剂磺化聚丁二烯LYF(1%～10%w/w)、内萃取剂HCl(1～5 mol.L-1)和水乳体积比A/O(2:1～7:1)对液膜萃取收率及稳定性的影响。在最优条件下,可回收94.10%～95.94%的镧,并且膜溶胀率为8%～17%,破损率为0.45%～1.93%,能够维持较好的液膜稳定性。研究结果对磷酸中的微量稀土镧回收利用具有一定的参考价值。
By slope analysis, the reaction mechanism and thermodynamics of liquid-liquid extraction of trace lanthanum from P204 and TOPO were studied. A possible reaction course and structure of the complex were deduced. The equilibrium constant of the extraction reaction and reaction was obtained as K = 104.502 , Enthalpy change ΔH = -13.02 kJ.mol-1, free energy ΔG = -25.686 kJ.mol-1, entropy change ΔS = 0.0425kJ. (Mol.K) -1. Based on the research of liquid-liquid extraction reaction mechanism, the enrichment and recovery of trace lanthanum in phosphoric acid system was studied by liquid membrane extraction. The effects of carrier P204 (2% -10% w / w) and TOPO (1% -10% (1% ~ 10% w / w), HCl (1 ~ 5 mol·L -1) and water / milk volume ratio A / O : 1 ~ 7: 1) on the yield and stability of liquid membrane extraction. Under optimum conditions, 94.10% ~ 95.94% of lanthanum can be recovered, and the swelling rate of the film is 8% ~ 17% and the damage rate is 0.45% ~ 1.93%, which can maintain good liquid film stability. The results have some reference value for the recovery and utilization of trace rare earth lanthanum in phosphoric acid.