STUDY ON DEGRADATION PRODUCTS OF 1MIDAZOLIUM IONIC LIQUIDS IN H_2O_2/UV OXIDATION SYSTEM

摘要

Ionic liquids are a novel, broad class of semi-organic salts or salt mixtures that are liquid below 100°C. The most attractive characteristics of ionic liquids is their potential to be 'designer solvents' by the appropriate selection of cation and anion. However the modern design of chemical products also takes into account prospective persistency in the environment which is a function of the overall stability against physico-chemical degradation processes as well as their toxicity and biodegradability. It is already known that commonly used alkylimidazolium ionic liquids are characterised by poor to negligible biodegradability as well as most of them are relatively toxic to the typical biological test systems. Therefore, when certain amounts of ionic liquids will be present in technological wastewaters, because of their high resistance to biodegradation and toxicity, they could become persistent pollutants and break through classical treatment systems into natural waters. We have recently found that the greatest degradation efficiency for imidazolium ionic iiquids in solution was achieved with the H_2O_2/UV system and the stability of analyzed compounds is structure-related. We have therefore employed high performance liquid chromatography coupled to the electrospray mass spectrometry to separate, analyze and identify degradation products of ionic liquids obtained after treatment of ionic liquids solutions with H_2O_2 in the presence of UV irradiation. We have found that for short chain entities hydroxylation occurs mainly within ring moiety whereas for longer alkylated cations, there are several products occurring from the oxidation of the alkyl chain. Identified structures of potential metabolites where further confirmed by MS/MS analysis.