Abstract: The removal of iron (Ⅲ) from sulphate solutions was investigated by solvent extraction using a mixed solvent system consisting of tertiary amine (N₂₃₅) and tributyl phosphate (TBP). The effect of extraction systems， concentration of N₂₃₅ and initial pH on the extraction of iron(Ⅲ)， as well as the effect of volume ratio of organic to aqueous(V_org/V_aq)， concentration of sulfuric acid and equilibrium pH on the stripping of iron(Ⅲ) in loaded organic phase were studied. The results demonstrate that the N₂₃₅-TBP system has a synergistic effect on the extraction of iron(Ⅲ)； By adding TBP in N₂₃₅, the demixing of loaded organic phase can be prevented and the stripping ratio of iron (Ⅲ) increases. Initial pH and concentration of N₂₃₅ have remarkable influences on iron (Ⅲ) extraction, the maximum on the extraction curve moves towards the direction of low pH with increasing concentration of N₂₃₅. At V_org∶V_aq of 2∶1， the concentration of iron(Ⅲ) in raffinate is less than 0.15 g/L after a three-stage cross-flow extraction with a organic phase consisting of 30%N₂₃₅ and 10%TBP and a total extraction ratio of nearly 99% is achieved for a feed solution containing 12.73 g/L Fe(Ⅲ). Furthermore， the stripping results indicate that with a dilute sulphuric acid (0.4 mol/L), iron stripping ratio can reach 96% controlling equillium pH less than 0.8. At V_org∶V_aq of 1∶1， iron(Ⅲ) in loaded organic phase containing 7.05 g/L Fe(Ⅲ) can be easily and completely stripped by a dilute sulphuric acid (0.4 mol/L) after a two-stage cross-flow stripping.

Key words: sulphate solutions; synergistic extraction;  stripping; iron(Ⅲ)　removal; tertiary amine; tributyl phosphate