K.Xieetal./SeparationandPuri cationTechnology76 (2010) 191–197197

4.Conclusion

Differentorganicextractants,polymersandinorganicsaltswereemployedinpreliminaryscreeningtestscarriedouttodeterminewhichofthesechemicalscouldcombinetoformstableorganicextractant–polymer–salttriphasicsystems.TheutilityoftheTESsonpartitionofTi(IV),Fe(III)andMg(II)wereassessed.Fromtheresults,TRPOandD2EHPAareconsideredtobeexcellenttopphase-formingcandidatesowingtotheirgoodphysicochemicalproperties.TheselectivityofmetalionswasfoundtodependonthepHvalueoftheaqueoussolution,thevalenceofmetalions,thepresenceofcomplexingagents,thehydrophobicitydif-ferenceamongphases,theextractedmetalspeciesandextractionmechanism.Themostimportantobservationinthepresentworkistheimprovementinaf nityofFe(III)forthePEG-richphaseandˇTi(IV)/Fe(III),t/mwhenEDTAisusedasacomplexingagent.ˇTi(IV)/Fe(III),t/msigni cantlyincreasedfromanegligibleamountto80usingTRPO–PEG2000–(NH4)2SO4TESatpH0.5.WhileMg(II)showedanabsolutepreferenceforthesalt-richbottomphase.TheseresultssuggestanexcitingpotentialmeansofseparationofTi(IV),Fe(III)andMg(II).

FurtherresearchisunderwaytocontinueoursurveyofusingtheTRPO–PEG2000andD2EHPA–PEG2000basedTESswiththecomplexingagentEDTAtosimultaneouslyseparateTi(IV),Fe(III)andMg(II)atalargeextent.Acknowledgement

TheauthorsthanktheNationalBasicResearchProgramofChina(973project2007CB613507)for nancingthiswork.References

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