Synergistic Extraction of Iron(III) from Sulphuric Acid Solutions with Mixed Kelex 100-Alkyl Phosphorus Acid Extract ants

ABSTRACT Synergistic extraction of Fe(ITI) from H2SO4 solutions, with a maximum at 130-150 g/1 H3SO4, is observed when using mixtures of Kelex 100 with di-alkyl phosphorus (HR) acids: D2EHPA, PC-88A, or Cyanex 272. No synergism, however, is observed when Kelex 100-M2EHPA mixtures are used The synergism is attributed to the formation of mixed metal-Kelex 100-HR-sulphate complexes. Based on the experimental data (continuous variation method, acid analysis of feed and rafiuiate solutions), the likely molar metal:Kelex 100:HR:SO4 2 ratio in the complex is 2:2:4:1. A reaction mechanism, rationalizing the observed synergism, together with the roles of Kelex 100 and HR, is suggested.