Crystallographic Insights into the Behavior of Highly Acidic Metal Cations in Ionic Liquids from Reactions of Titanium Tetrachloride with [1-Butyl-3-Methylimidazolium][X] Ionic Liquids (X = Chloride, Bromide, Tetrafluoroborate).

Highly charged metal ions are difficult to investigate in weakly coordinating ionic liquids (ILs) because of the insolubility of their solid forms, but the molecular liquid TiCl4 offers a way to react tetravalent metal ions in an IL. Reactions of TiCl4 with 1-butyl-3-methylimidazolium ([C4mim]+)-based ILs containing chloride or bromide lead to mixtures of highly metastable amorphous solids and small amounts of crystalline chlorotitanate salts including [C4mim]2[TiCl6] and two polymorphs of [C4mim]2[Ti2Cl10] in a manner not well correlated with stoichiometry or anion identity. The reaction of TiCl4 with [C4mim][BF4] yields crystals of the mixed fluoro-chloro complex [C4mim]2[Ti4F6Cl12], indicating spontaneous reaction of the IL ions to generate HF in situ. These unusual behaviors are explained in terms of the exceptionally high acidity of Ti4+ and the unusual behavior of TiCl4 among metal halides as a nonpolar molecular compound.

Ionic liquid-based routes to conversion or reuse of recycled ammonium perchlorate.

New, potentially green, and efficient synthetic routes for the remediation and/or re-use of perchlorate-based energetic materials have been developed. Four simple organic imidazolium- and phosphonium-based perchlorate salts/ionic liquids have been synthesized by simple, inexpensive, and nonhazardous methods, using ammonium perchlorate as the perchlorate source. By appropriate choice of the cation, perchlorate can be incorporated into an ionic liquid which serves as its own electrolyte for the electrochemical reduction of the perchlorate anion, allowing for the regeneration of the chloride-based parent ionic liquid. The electrochemical degradation of the hazardous perchlorate ion and its conversion to harmless chloride during electrolysis was studied using IR and (35)Cl NMR spectroscopies.

The opposite effect of temperature on polyethylene glycol-based aqueous biphasic systems versus aqueous biphasic extraction chromatographic resins.

Variation in operational temperatures has revealed differences in the partitioning behavior of probe solutes between the phases in aqueous biphasic systems (ABS) and the related aqueous biphasic extraction chromatographic resin (ABEC). This difference has been studied using the hydrophobic anion, 99TcO4-, as a probe and (NH4)2SO4 as the kosmotropic salt. Distribution of the hydrophobic anion 99TcO4- to the PEG-rich phase in a MePEG-5000/(NH4)2SO4 ABS increases with increasing temperature, but decreases are observed in batch uptakes of this anion to ABEC resins from (NH4)2SO4 solutions. Phase diagrams were constructed at five different temperatures from 10 to 50 degreesC using cloud point titration for the ABS and a correlation between the phase divergence, measured in terms of tie line length (TLL), and the temperature of the partitioning system was verified. Thermodynamic parameters (deltaHdegrees,deltaSdegrees, deltaGdegrees, ) as a function of temperature were calculated for the various systems studied and the results imply thermodynamic differences between partitioning in ABS versus ABEC.

Removal of textile dyes from textile dye effluent using TBAB based aqueous biphasic systems.

Aqueous biphasic systems (ABS) are useful for the extraction of dye molecules from aqueous solution. Thus, they can be used in textile dye bath effluent treatment. The partitioning behavior of two commercially used textile dyes-Cibacron Scarlet LS 2G and Astacryl Red 3B were investigated in a TBAB-salt aqueous biphasic systems. It was found that all three salts, namely sodium chloride, sodium sulphate and sodium carbonate, investigated caused partitioning of dye into the upper TBAB rich phase. The efficiency of separation increased in the order NaCl < Na2SO4 < Na2CO. It was found that the cationic dye partitioned better than the anionic dye in the system. A concentration of 5 g/l of dye was extracted into the upper layer. Alteration of solution pH did not cause any significant difference in distribution ratios. Studies were extended to actual dye bath effluent and small scale up studies carried out. Efficiencies of removal obtained in all cases were extremely good with maximum efficiencies above 98 %.