Synthesis Of N,N'-di(2-ethylhexyl)-Diglycolamic Acid And Its Extraction Study Of Ln(?)from Nitric Acid

In the sustainable development of nuclear energy,treatment and disposal of high level liquid waste has become a key problem to restrain the development of nuclear power.Solvent extraction has been playing an important role in the separation of high-level radioactive waste liquid.So the performance of the extraction agent and process development research has been a research hot spot in high-level radioactive waste liquid solvent extraction separation for years.The study found that acid extraction agent,such as N,N-di(ethyl hexyl)phosphoric acid(HDEHP),was an efficient extraction agent for the separation of lanthanide and actinide elements.But these extraction agents which contained a P in the molecular structure,can't complete combustion and increase the amount of secondary waste.The extraction solvent N,N-di(ethylhexyl)diglycolamic acid(DEHDGA: HL)was synthesized in this paper using diethylene glycol as raw materials,containing only C,H,O,N four kinds of elements,can complete combustion,and the combustion gas products does not increase the secondary of solid waste.And the DEHDGA was entirely studied,with dodecane as diluent,for extraction behavior of Dy(?)with DEHDGA from 3.0 mol/L nitric acid medium and extraction behavior of La(?)with DEHDGA from 0.3 mol/L nitric acid medium.Comparative research on extraction behavior of Ln(?)with DEHDGA from 3.0 mol/L and 0.3 mol/L nitric acid medium.And results obtained from the study are listed as follows:(1)The extraction solvent N,N-di(ethylhexyl)diglycolamic acid(DEHDGA)was synthesized,and the structure have been characterized through the methods of high performance liquid mass spectrometry(LCMS),infrared spectra(IR),nuclear magnetic resonance(1H NMR,13 C NMR),mass spectrometry(MS)and elemental analysis.(2)In the range of 0.21 ~ 4.14 mol/L HNO3 concentration,the change trend of distribution ratio of 14 kinds of lanthanides metal elements is roughly same.at first the distribution ratio,DLns,decreases then increases with the increase of the acid concentration,indicating that the extraction mechanisms of 14 kinds of lanthanides elements are the same.It's all ion exchange mechanism under the condition of low acid and It's Neutral complexing mechanism under the condition of high acid,while near the minimum value with the two kinds of mechanism coexistence.(3)In 3.0 mol/L nitric acid system,the reaction equation of DEHDGA extraction Dy(?)is deduced to be:Dy3+ + 2 HL + 3 NO3-= Dy(HL)2(NO3)3(4)In 0.3 mol/L nitric acid system,the reaction equation of DEHDGA extraction La(?)is deduced to be:La3+ + 2HL+ NO3-= La� 2L-�NO3 + 2H+(5)the coordination numbers which lanthanides elements coordinate with extractant molecules are the same in 3.0 mol/L and 0.3 mol/L HNO3 medium,with a trivalent metal ions complexation two DEHDGA moleculars.While NO3-molecules involved in the complexation are different from La to Lu,indicating that the composition of extracted complex that light lanthanides and heavy lanthanides involved in the same concentration of HNO3 in aqueous solution is different,and the extracted species of the same lanthanide element involved in different acidity solution are also different.(6)distribution ratio of 14 lanthanides elements increases with the increase of atomic number from La to Lu,and the mutual separation factor of light lanthanidesis is greater than the heavy lanthanides.Distribution ratio of 14 lanthanides reduce with the increase of temperature,which shows that the reactions of DEHDGA extraction lanthanides are exothermic reaction and raising the temperature go against the extraction of lanthanides.