N_(7402)萃取铂(Ⅳ)的机理和热力学研究

Extraction mechanism and thermodynamics of platinum with N_(7402)

研究了氯化三烷基甲基铵 N_(7402)煤油溶液从盐酸介质中萃取铂(Ⅳ)的平衡.考察了酸度、萃取剂浓度和温度等因素对铂萃取的影响;用饱和法、摩尔比法、等摩尔系列法和斜率法确定萃合物的组成为(R_3NCH_3)_2PtCl_6;并通过紫外可见光谱证实该萃取过程属于阴离子交换机理,测得表观萃取平衡常数 K_(ex)=158.6,变△H=0.154kJ·mol^(-1),自由能变△G=-12.55kJ·mol^(-1),熵变△S=41.60J·mol^(-1)·K^(-1)。

The extraction mechanism and thermodynamics of Pt(Ⅳ)from HCl medium with N_(7402)is studied.The influences of the concentration of N_7402、Cl^-、the pH value and temperature on the distribution ratio D are examined and the composition of the extracted complex (R_3NCH_3)_2PtCl_6 is determined by the methods of slope,constant mole and others.The extraction mechanism of Pt(Ⅳ)with N_7402 based on UV-vis spectra is proved to be an anion exchange reaction: PtCI_6(o)^(2-)+2R_3NCH_3Cl_(o)(?)(R_3NCH_3)_2PtCl_6(o)+2Cl_(a)^- Meanwhile,the equilibrium constant of extraction reaction and the values of thermodnyamies function at 25±1℃ are calculated.