硫氰酸甲基三烷基季铵盐萃取Co(Ⅱ)的动力学

KINETICS OF SOLVENT EXTRACTION OF COBALT(Ⅱ) BY QUATERNARY AMMONIUM THIOCYANATE

有关Co(Ⅱ)、Ni(Ⅱ)萃取分离的研究一直受到人们的重视。Preston报导了硫氰酸季铵盐(Q^+SCN-)萃取Co(Ⅱ)、Ni(Ⅱ)的平衡研究,认为Co(Ⅱ)的萃合物组成为Q_2Co(SCN)_4.本文用上升液滴法技术考察了Co(Ⅱ)/0.10mol·L^(-1)SO_4^(2-)/QSCN-煤油体系在298±1K条件下萃取速率R与CoSO_4、SO_4^(2-)和QSCN浓度的关系,确定了正向初始萃取速率方程,拟定了速控步骤。

The kinetics and mechanism of the extraction of Co(Ⅰ) from sulphate solution withquatornary ammonium thiocyanate (QSCN, Q-CH_3 N [CH_2(CH_2)_(6-10)CH_3]_3) in kerosenewere studied by means ot single drop method at 298K. The experimental results indicatethat the extraction process is controlled by the following interface reactions:CoSO_4+2QSCN(i)K_2?K_(-1)CoSO_4.2QSCN(i)slowCoSO_4.2QSCN(i)+2QSCN_(o)K_2?K_(-2)Co(SCN)_(4(o))+ Q_2SO_4,slowlgK_1′=lgK_1[QSCN]~2(i)=-4.49;lgK_(-1)/K_2=2.56.where(o)and(i)represent organic phaseand interface, respectively.