Continuous process for selective metal extraction with an ionic liquid

D. Parmentier, S. Paradis, S.J. Metz, S.K. Wiedmer, M.C. Kroon

    Research output: Contribution to journalArticleAcademicpeer-review

    19 Citations (Scopus)

    Abstract

    This work describes for the first time a continuous process for selective metal extraction with an ionic liquid (IL) at room temperature. The hydrophobic fatty acid based IL tetraoctylphosphonium oleate ([P8888][oleate]) was specifically chosen for its low viscosity and high selectivity towards transition metals. Applying [P8888][oleate] for continuous metal ion extraction with 0.1 M sodium oxalate for regeneration resulted in a process with good and stable extraction efficiencies over time. The selectivity of the IL resulted in a process in which cobalt was selectively removed from two mixed salt solutions (Co/Na, Ca/Co/K) to obtain a pure cobalt stream after stripping the IL. The performed experiments showed that the contact time of the IL for extraction and stripping strongly influenced the achieved efficiencies. The stability of the IL was tested and it was shown that the fatty acid based IL was stable for the duration of the experiment. Liposome tests showed that the IL is very hydrophobic, which limits its leakage towards the water phase, but also results in a higher toxicity towards cell membranes. Economic analysis shows that the IL based process is not (yet) economical compared to ion-exchange resins, in case demineralised water is the only product. However, if the recovery of valuable metals is also taken into account and/or if brine disposal is an issue, then continuous IL metal extraction systems must be regarded as promising alternatives.

    Original languageEnglish
    Pages (from-to)553-560
    Number of pages8
    JournalChemical Engineering Research and Design
    Volume109
    DOIs
    Publication statusPublished - 1 May 2016

    Keywords

    • Continuous metal extraction
    • Ionic liquid
    • Selective metal extraction
    • Tetraoctylphosphonium oleate
    • Transition metals

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