TODGA/正十二烷萃取Am(Ⅲ)的动力学

朱文彬; 叶国安; 李峰峰; 李会蓉

doi:10.7538/hhxyfshx.2013.35.03.0136

TODGA/正十二烷萃取Am(Ⅲ)的动力学

Extraction Kinetics Behavior of Am(Ⅲ) by TODGA

摘要

摘要: 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Am(Ⅲ)的动力学，考察了搅拌转速、两相界面面积、萃取剂浓度、金属离子浓度、酸度和温度等因素对Am(Ⅲ)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130 r/min以下时，0.1 mol/L TODGA/正十二烷萃取Am(Ⅲ)的过程为扩散控制类型，在搅拌转速为150 r/min以上时，则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0.1 mol/L TODGA/正十二烷萃取Am(Ⅲ)的初始速率方程：
r₀=(dc_org(M)/dt)_t=0=k•(S/V)c^0.94_aq,0(Am)c^1.05_aq,0(HNO₃)c^1.19_org,0(TODGA)
在25℃下，求得表观速率常数k=(24.2±3.4)×10^-3mol^-2.18•L^2.18•min^-1•cm；(3) 0.1mol/L TODGA/正十二烷萃取Am(Ⅲ)的初始速率随着温度的升高而增大，求得表观活化能E_a=(25.94±0.98)kJ/mol。

Abstract: In the present paper, N, N, N′, N′-tetraoctyl diglycolamide(TODGA) as the extractant and n-dodecane as the diluent, the extraction kinetics behavior of Am(Ⅲ) in TODGA/n-dodecane HNO₃ system was studied, including stirring speed, the interfacial area, extractant concentration in n-dodecane, extracted ions concentration, acidity of aqueous phase and temperature. The results show that the extraction process is controlled by diffusion under 130 r/min of stirring speed and by chemical reaction above 150 r/min. The extraction rate equation and the apparent extraction rate constant of Am(Ⅲ) 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^0.94_aq,0(Am)c^1.05_aq,0(HNO₃)c^1.19_org,0(TODGA)
k=(24.2±3.4)×10^-3mol^-2.18•L^2.18•min^-1•cm，E_a=(25.94±0.98)kJ/mol.

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