The kinetics and mechanism of solvent extration of iron(III) with a n-octane solution of 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEHEHP) has been studied at ionic strength 0.1 and 298 ?1 K by means of the high-speed stirring method. In order to further understand the reaction mechanism of iron(III) with HEHEHP and to explain the catalytical role of trioctyl phosphine oxide (TOPO) and sodium dodecyl sulfonate (SDS) on the kinetic processes, so as to determine the exact location of the rate controlling steps in the reaction system, the adsorption activity of HEHEHP, TOPO and SDS at n-octane/0.100mol.dm-3 nitrate interface was measured resp. The results indicate that TOPO decelerates the extration rate of iron(III) with HEHEHP, but SDS accelerates it. The influence of TOPO and SDS on the extration rate of iron(III) with HEHEHP was quant. dealed with.

Key words: IRON, SOLVENT EXTRACTION, ETHYLHEXYL PHOSPHONIC ACID MONOETHYL HEXYLESTER, TRIOCTYL PHOSPHINE OXIDE, EXTRACTION MECHANISM