稀散金属铊(Ⅰ)的溶剂萃取热力学研究

Studies on Thermodynamics of Solvent Extraction ofRare and Scattered Metal Tl(I)

以萃取剂二—(2—乙基己基)二硫代磷酸(HR),稀释剂正辛烷,研究萃取铊(Ⅰ)的热力学.在HR+Tl2SO4 +n C8H18 +Na2SO4 +H2O体系中,在温度 278. 15 ~298. 15K和离子强度 0. 1 ~2. 0mol·kg-1范围内,以Na2SO4 为支持电解质,在H2SO4 体系中测定了萃取平衡水相中Tl+浓度和pH值.应用直线外推法在计算机上通过EXCEL计算了萃取反应的标准平衡常数K0,并得到经验公式lgK0 =62.7-7.73×103 /T-0.118×10-2T,同时计算了萃取反应的其他热力学量,指出焓和熵是该萃取过程的推动力.

This paper reported the thermodynamics of extracting Tl(I) with the extractant of Di-di-ethylhexyldithiohoric Acid in the H_2SO_4 system. The equilibrium molalities of Tl^+ and pH in the extraction:Tl^++HR (org)=TlR(org)+H^+ were measured at ionic strengths from 0.1 to 2.0 mol·kg^(-1) in the aqueous phase containing Na_2SO_4 as the supporting electrolyte and at constant initial molality of extractant in the organic phase at temperatures from 278.15 to 303.15K. The standard equilibrium constant K^0 at extraclion were obtained by EXCEL and the thermodynamic quantities for the extraction process were calculated.