Studies On The Extraction And Separation Of Am(Ⅲ) And Eu(Ⅲ) The Open-Chain Macrocyclic Compounds By The Tracer Method

The extraction and separation of Am(â…¢)/Eu(â…¢)with 23 open-chain rnacrocyclic compounds as extractants were investigated systematically by the radioactive isotopic tracer technique.The extraction distribution.ratios have been measured as a function of shaking time,counteran ion,pH value,picric acid concentration,extractant concentration,type of diluent and temperature.The compositions of the extracted species were ascertained by use of the slope method.The equilibrium constants (logL_ex)and the thermodynamic parameters(AG,â–³H andâ–³S)of some extraction reactions were also calculated.The stability of the rare earth picrate complexes with open-chain macrocyclic compounds was described quantitatively.The conclusions can be drawn from the thesis as follows:(1)The extractability of the tetrapodal type open-chain cryptands for Am(â…¢)is hrger than that of the open-chain crown ethers.(2)The extractability of the tetrapodal type open-chain cryptands for Am(â…¢) depends primarily on the competition of conjugate plane effect and space steric role of the benzene ring.The compounds were disubstituted at the amide nitrogen atoms by one phenyl.(3)The extractability of open-chain crown ethers with the same skeleton for Am(â…¢)depends primarily on the substituting groups of the amide nitrogen atoms.(4)The extractability of the open-chain crown ethers for Am(â…¢)depends on the skeleton of extractant molecule.(5)Among the open-chain crown ethers and cryptands with the same structure, the compounds disubstituted at the amide nitrogen atoms show the higher extractability for Am(â…¢)than the monosubstituted ones.(6)The extractability of the open-chain crown ethers and cryptands for Am(â…¢) increased with increase in the dielectric constants of the diluents,and with decrease in the temperature.(7)The extractability and separability of Sophie chain Schiff bases(â…¢₃,â…¢₄,â…¢₅ )for Am(â…¢)and Eu(â…¢)increase with increasing of coordination point.Much useful fundamental data for the studies on the open-chain rnacrocyclic compounds as extractants have been given in the thesis.These data are very helpful to explore further the extraction mechanism and regularity of the open-chain rnacrocyclic compound as the extractant,and the relationship between structure and property of the extractant,and to find the fine extractant with high selectivity.