TODGA/正十二烷萃取Sr(Ⅱ)的动力学

以N,N,N′,N′-四辛基-3-氧戊二酰胺(TODGA)为萃取剂、正十二烷为稀释剂，研究了该萃取体系在恒界面池中萃取Sr(Ⅱ)的动力学，考察了搅拌转速、界面面积、萃取剂浓度、金属离子浓度、酸度和温度等因素对萃取行为的影响，并推导了相应的萃取机理。结果表明：(1) 搅拌转速在130r/min以下时，0.1mol/L TODGA/正十二烷萃取Sr(Ⅱ)的过程为扩散控制类型，在搅拌转速为150r/min以上时，则可能属于化学反应控制的动力学控制模式；(2) 求得了在(170±2)r/min、温度为(25±0.1)℃时0.1mol/L TODGA/正十二烷萃取Sr(Ⅱ)的初始速率方程： r₀= ((dc_org(M)/dt) |_t=0)=k? (S/V)c^0.91_aq,0(Sr)c^0.73_aq,0(HNO₃)c^0.87_org,0 (TODGA) 在25℃下，求得表观萃取速率常数k=(22.5±2.5)×10^-3mol^-1.51?L^1.51?min^-1?cm；(3) 0.1 mol/L TODGA/正十二烷萃取Sr(Ⅱ)的初始速率随着温度的升高而增大，求得表观萃取活化能E_a(Sr(Ⅱ))=(24.3±0.7)kJ/mol。

Kinetics and Mechanism of Sr(Ⅱ) Extraction With TODGA

In the present paper, N,N,N’,N’-tetraoctyl diglycolamide (TODGA) as the extractant and n-dodecane as the diluent, the extraction kinetics behaviors of Sr(Ⅱ) in TODGA/n-dodecane HNO₃ system were studied, including stirring speed, specific interface, extractant concentration in n-dodecane, Sr²⁺ concentration of aqueous phase, HNO₃ concentration of aqueous phase and temperature. The results show that the extraction process is controlled by diffusion mode under 130 r/min of stirring speed and by chemical reaction mode above 150 r/min. The extraction rate equation and the apparent extraction rate constant of Sr(Ⅱ) by TODGA/n-dodecane in (170±2) r/min and (25±0.1)℃ are as follows:  r₀= ((dc_org(M)/dt) |_t=0)=k? (S/V)c^0.91_aq,0(Sr)c^0.73_aq,0(HNO₃)c^0.87_org,0 (TODGA) k=(22.5±2.5)×10^-3mol^-1.51?L^1.51?min^-1?cm；E_a(Sr(Ⅱ))=(24.3±0.7)kJ/mol.