Preparation Of Novel Alkylimidazolium Ion-selective Electrodes And Its Performances

In the past decades, a large number of novel ionic liquids have been synthesized and applied in manyaspects. Ionic liquids, as environment-friendly media, have received extensive attention because they havenegligible vapor pressure. They cannot be evaporated to the environment, but they are released possiblyinto the environment. In recent years, it has been proved that many ionic liquids have some toxicity. It ismore import to establish a simple and fast method to detect ionic liquids which lost into the environment.Alkylimidazolium ionic liquids are a tape of the widely used ionic liquids. As a part of National NaturalScientific Foundation of China (No.21173070), the self-prepared PVC membrane electrodes, carbon pasteelectrodes, and molecularly imprinted polymer (MIP) electrodes were developed for detection of thealkylimidazolium ionic liquids, and the PVC membrane electrodes were used to determine the activitycoefficients of alkylimidazolium ionic liquids in water and fructose+water mixed solvents. Major contentsare as follows:1. Activity coefficients of1-alkyl-3-methylimidazolium bromide [Cnmim]Br (n=3–8) ionic liquids(ILs) in water and in fructose+water mixed solvents at298.15K were determined using self-preparedPVC membrance electrodes. The molalities of [Cnmim]Br ranged from0.005to0.1mol·kg1, and those offructose from0.2to0.8mol·kg1. Gibbs free energy interaction parameters (gES) were obtained togetherwith salt constants (kS). The results show that the interactions between [Cnmim]Br and fructose are mainlycontrolled by electrostatic interactions. The salting constants are negative for the ILs (n=3–6), indicatingthat fructose are salted-in by the ILs in water, whereas fructose are salted-out by the ILs (n=7and8).2.1-Hexyl-3-methylimidazolium tetraphenylborate ([C6mim]-TPB) was synthesized and explored as the ion exchanger in carbon paste electrodes (CPEs). The CPE modified by multi-walled carbon nanotubes(MWCNTs) and nano-silica showed a Nernstian response to1-hexyl-3-methylimidazolium cation (59.2mV). The electrode was found to be optimal with the composition of42%graphite powder,20%paraffinoil,30%ion exchanger,5%MWCNTs, and3%nano-silica. The self-prepared MWCNTs/Nano-silica/CPEswere successfully applied in the detection of [C6mim]+in distilled water, tap water and river water withsatisfactory results.3. Using the1-hexyl-3-methylimidazolium chloride as a template, the molecularly imprinted polymer(MIP) of1-hexyl-3-methylimidazolium cation was synthesized. Then the molecularly imprinted polymerwas doped into carbon paste to prepare carbon paste electrodes, and the electrochemical impedancespectroscopy (EIS) of as-prepared electrode was preliminary received, indicating that carbon pasteelectrode with molecularly imprinted polymer has a very small electron transfer resistance. This method isfavorable to prepare ion-selective electrodes with MIP.