Use of 1-hexyl-3-methylimidazolium bromide ionic liquid in the recovery of lactic acid from wine

BACKGROUND: Lactic acid has many different applications in a variety of industries including the food, cosmetics, packaging, leather and chemical industries. Current methodologies for lactic acid production are lengthy and complicated and more efficient methods are being sought. Some organic wastes contain lactic acid and our work investigates the use of ionic liquids (ILs) in the efficient and selective extraction of lactic acid from organic waste using wine as a model system. The ionic liquid was chosen based on its ability to selectively solvate and separate lactic acid from the remaining bulk waste material. RESULTS: Several ILs including 1-hexyl-3-methylimidazolium chloride (hmimCl), 1-hexyl-3-methylimidazolium bromide (hmimBr), 1-hexyl-3-methylimidazolium iodide (hmimI) and N-hexylpyridinium iodide (hpyrI) have been synthesized in high yield (68-95%) using microwave technology. Lactic acid is soluble in each of the ILs synthesized with optimum results achieved with hmimBr where lactic acid is miscible in all proportions. HmimBr has been used to successfully separate and extract lactic acid from wine as confirmed by FTIR spectroscopy. Furthermore, it has been possible to recover the IL for recycle in subsequent extraction cycles where the efficiency for the extraction process increases with each recycle. CONCLUSION: HmimBr has been used for the first time in a novel process for the separation and recovery of lactic acid from wine, as confirmed by FTIR spectroscopy. This work demonstrates a novel process which can be applied to the recovery of lactic acid from organic waste. Copyright (C) 2012 Society of Chemical Industry