甲基异丁酮碘萃合物-水界面上的循环伏安法间接测定水溶液中氧化性金属离子

Indirect Determination of Oxidative Metal Ion by Extracting Iodine from Aqueous Solution with Methyl Isobutyl Ketone by Three-electrode Cyclic Voltammetry at the Interface Between Two Immiscible Electrolyte Solution

利用甲基异丁酮(MIBK)作为萃取剂,等体积法将水中的碘萃取到有机相中,微量进样器将20～40μL有机溶液注入玻璃微管中,使它处于界面上。利用经典的三电极系统研究该有机相在液/液界面的伏安特性。实验结果表明,该过程是一个受扩散控制的不可逆过程。有机相中碘的含量和峰电流大小在一定范围内成正比。利用这一特性可以间接测定水溶液中具有氧化性的金属离子(如Cr2O72-、Cu2+等)的含量,检出限为10-5mol/L。

Iodine equi-volume extracted with methyl isobutyl ketone from aqueous solution, and then 20 -40 μL of an organic solution containing iodine was injected into a pipette using a microsyringe, and the combine electrode was set just on the surface of the aqueous solution. The electrochemical characteristic of organic solution at the liquid/liquid interface was studied. The process was controlled by diffusion and irreversible. The concentration of iodine was proportional to oxidation peak current. This study showed that it was possible to determine the content of oxidative metal ion （e. g. Cu^2＋ , Cr2 O7^2- ） indirectly which can oxidate iodide to iodine by classic cyclic voltammetry, the detection limit was 10^-5 mol/L.