Efficient ionic liquid based mercury scrubbing technology from gram to ton scale.

A range of chloroindate(III) ionic liquid systems was prepared by mixing of 1-alkyl-3-methylimidazolium chloride with indium(III) chloride in various ratios, expressed as the mol fraction of indium(III) chloride, χ InCl₃ . For χ InCl₃ ≤ 0.50, the products were liquids, whereas for χ InCl₃ > 0.50, the products were biphasic (suspensions of a solid in an ionic liquid). Speciation of these chloroindate(III) systems was carried out using a wide range of techniques: differential scanning calorimetry (DSC), polarised optical microscopy (POM), liquid-state and solid-state ¹¹⁵In NMR spectroscopy, X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS). Ionic liquids prepared using an excess of the organic chloride (χ InCl₃ < 0.5) contained [InCl₆]^{3 −}, [InCl₅]^{2 −} and [InCl₄ ]⁻ anions, in proportions dependent on the χ InCl₃ value. Equimolar mixtures yielded single compounds: 1-alkyl-3-methylimidazolium tetrachloroindates(III). Systems containing an excess of indium(III) chloride (χ InCl₃ > 0.5) contained indium(III) chloride powder suspended in a neutral tetrachloroindate ionic liquid.