液膜萃取法回收磷酸体系中的微量镧

Recovery of Trace Lanthanum from Phosphoric Acid Using Liquid Membrane Extraction

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。

The liquid-liquid extraction reaction mechanism and thermodynamics of the P204 and TOPO leaching trace lanthanum from phosphoric acid were studied using slope-analysis method.A most plausible reaction path and structure of complexes was inferred.The thermodynamic parameters such as K=104.502,ΔH=-13.02 kJ · mol-1,ΔG=-25.686 kJ · mol,ΔS=0.0425 kJ ·（mol · K）-1 were determined.Based on the study of liquid-liquid extraction mechanism,the enrichment recovery of trace lanthanum from phosphoric acid using liquid membrane extraction method was researched,and then the effect of the concentrations of the carrier P204（2% ~10% w/w） and TOPO（1% ~10% w/w）,surfactant sulfonated liquid polybutadiene LYF（1% ~10% w/w）,stripping agent HCl（1~ 5 mol · L-1）,and the volume ratio of aqueous phase to the emulsion phase（A/O 2∶ 1~7∶ 1） on the extraction efficiency and stability of liquid membrane was investigated.At the optimum condition it was possible to recover 94.10% ~95.94% of lanthanum and to keep the better stability of liquid membrane for the swelling ratio of 8% ~17% and breakdown ratio of 0.45% ~1.93%.The results of the study afford a possibility for the recovery of trace lanthanum from phosphoric acid. 更多