【摘要】 本文研究了HEH[EHP]的正己烷溶液在不同浓度(0—11M)的硝酸介质中萃取稀土元素(Ⅲ)的平衡规律。借助IR、NMR测定和斜率法研究了不同硝酸浓度下的萃取平衡反应,计算了不同萃取机理的浓度平衡常数。研究了温度和溶剂对萃取平衡的影响,测定了不同硝酸浓度和温度下各相邻元素对的分离因数,计算了萃取平衡反应的焓变值△H、相对自由能变化值△Z_?以及相对熵变值△S_?,并考察了这些热力学函数随原子序数的递变规律。更多还原

【Abstract】 The extraction behaviour of rare earth elements（Ⅲ） from nitric acid soltition byHEH[EHP]-hexane has been systematically investigated. The mechanism of extractioncarried out in different acidities is discussed in terms of slope, IR and NMR data obtai-ned. It is concluded that at low aqueous acidity, rare earths（Ⅲ） are extracted by acation-exchange reaction with hydrogen liberation: K₁ Ln³⁺+ 3（HL）_{2 （0）}?Ln（HL₂）_3（0）+3H⁺ （1）and at high aqueous acidity the extraction is accompanied by a solvation reaction simi-lar to that for TBP; K₂ Ln³⁺+3NO₃^-+2（HL）_2（o）?Ln（NO₃）₃·4HL_o （2） The influences of temperature and solvent upon the extraction equilibrium under dif-ferent conditions were discussed in detail. The equilibrium constants （K₁ anb K₂） andthe thermodynamic functions （ΔH, ΔZ_n and ΔS_z）of extraction reaction were calculated.The dependency of K,ΔZ_z and ΔS_z on the atomic number of rare earth elements werealso discussed.更多还原