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对二异丁基甲酮(DIBK)和TBP从HSCN介质中协同萃取锆铪的性能及热力学进行研究,采用对数函数外推法求得DIBK-TBP体系萃取反应的热力学平衡常数分别为log(K12,Zr)=4.73和log(K12,Hf)=-5.09,锆铪与SCN-形成配合物Zr(SCN)3+和Hf(SCN)3+的稳定性常数分别为1×109.86和1×10-0.80,而铪的分配比在硫氰酸盐存在时要大于锆的分配比,说明过渡金属离子锆和铪在硫氰酸盐存在时与一般金属离子与配位体形成的配合物的稳定性常数愈大,金属离子的分配比愈大的规律相矛盾,并计算出萃取反应的焓变分别为ΔHZr=-11.43 kJ.mol-1和ΔHHf=-7.80 kJ.mol-1,说明对锆铪的萃取反应为放热反应,升高温度不利于萃取反应的进行,常温下自由能变分别为ΔGZr=-26.54 kJ.mol-1和ΔGHf=28.57 kJ.mol-1,熵变分别为ΔSZr=51.54 J.(K.mol)-1和ΔSHf=-124.07 J.(K.mol)-1,说明铪离子比锆离子更易与SCN-形成配位键,从而生成中性分子Hf(SCN)4与有机相发生溶剂化作用而进入有机相中。
The performance and thermodynamics of synergistic extraction of zirconium and hafnium from di-isobutyl ketone (DIBK) and TBP from HSCN media were studied. The thermodynamic equilibrium constants of extraction reaction of DIBK-TBP system were log (K12, Zr = 4.73 and log (K12, Hf) = -5.09. The stability constants of Zr (hafnium) and SCN-forming complexes Zr (SCN) 3+ and Hf (SCN) 3+ are 1 × 109.86 and 1 × 10- 0.80 and the distribution of hafnium is greater than the distribution ratio of zirconium in the presence of thiocyanate, indicating the stability of the transition metal ions zirconium and hafnium in the presence of thiocyanate with the complexes formed by the general metal ion and the ligand The larger the constant, the distribution of metal ions is more contradictory than the larger rule, and calculate the enthalpy change of the extraction reaction were ΔHZr = -11.43 kJ.mol-1 and ΔHHf = -7.80 kJ.mol-1, indicating that zirconium and hafnium Of the extraction reaction is exothermic reaction, the increase of temperature is not conducive to the extraction reaction at room temperature, free energy change were ΔGZr = -26.54 kJ.mol-1 and ΔGHf = 28.57 kJ.mol-1, the entropy change were ΔSZr = 51.54 J. (K.mol) -1 and ΔSHf = -124.07 J. (K.mol) -1, indicating that hafnium ions are more likely to form coordination bonds with SCN- than zirconium ions, resulting in the formation of the neutral molecule Hf (SCN) 4 Made with organic Solvation into the organic phase.