D₂EHPA를 포함하는 지지액막을 통하여 Co(II)를 추출하는 실험에서, 액막중 D₂EHPA의 농도, Feed중 초기 Co(II)농도, 초기 수소이온 농도의 변화에 따른 추출속도를 측정하였다.
D₂EHPA와 Co(II)의 Feed측 수상계면에서의 1차 반응과 액막내 Co(II) 착제의 확산을 속도지배단계로 하여 다음의 투과속도식을 제안하고 실험결과와 비교 검토하였다.
ln(C_M/C_M^o) - q(1-C_M/C_M^o) = pt
모든 실험데이타는 제안된 식에 의하여 잘 상관시킬 수 있었다. 이 식중에 q는 막중 D₂EHPA농도와, Feed중 초기 Co(II)에 무관하며, Feed중 초기 수소이온 농도에 비례하였으며, p는 D₂EHPA 농도에 비례하고 Feed중 초기 Co(II)와 수소이온 농도에 반비례하였다.

The extraction of cobalt(II) was carried out using a supported liquid membrane containing di(2-ethyl hexyl)phosphoric acid(D₂EHPA)as a mobile carrier, and the effects of concentrations of carrier as well as initial cobalt(II)and hydrogen ion concentrations of the feed on extraction rates were investigated. Taking into account interfacial first order reaction between Co(II) and D₂EHPA, and membrane diffusion as simul-taneous controlling factors, an equation describing the permeation rate has been derived as follow.
ln(C_M/C_M^o) - q(1-C_M/C_M^o) = -pt
In this equation, q was affected proportionally to hydrogen concentration in feed solution, and p was affected pro-portionally to D₂EHPA concentration in oil phase and inversely proportional to initial concentration of Co(II) and hy-drogen ion in feed aqueous solution. The experimental values can be correlated well by the equation.