Phase transfer of the 12-tungstosilicate anion across the water/nitrobenzene interface

Abstract

The transfer behaviour of the heteropoly anion [SiW12O40]4– across the water/nitrobenzene interface has been investigated using cyclic voltammetry and chronopotentiometry with cyclic linear current scanning. It was found that the heteropoly anion with a negative charge of 4 can transfer from the aqueous phase to the organic phase electrochemically. The transfer process is diffusion-controlled at a lower scan rate, but it is partially kinetically controlled at a higher scan rate. The effects of some higher-valent cations such as Sr2+, Co2+, Ni2+, Zn2+, Fe2+ and Fe3+, as well as some anions such as NO–3, Cl–, SO2–4 and PO3–4etc. on the phase transfer have been systematically observed from cyclic voltammograms. The formal transfer potential and the transfer free energy for the heteropoly anion across the water/nitrobenzene interface have been calculated according to the voltammetric data.