Synthesis Of Benzimidazolium Ionic Liquids And Their Application In Extraction Separation

Recently, synthesis and application of novel, functionalized ionic liquids(ILs) have been one of the hot topics in green chemistry. At present, the most publications in this area focus on the electrochemical electrolyte, solvent of synthesis and extraction agent of separation technology. ILs have been proven as the efficient green extractant because of their unique properties including low melting point, high stability, low vapour pressure, and tunable solubility.In order to find a good extractant of aromatic compounds, a series of benzimidazolium ILs were designed and synthetized based on the mechanisms of interaction between ILs and aromatic hydrocarbons. Their structures and compositions were characterized by FT-IR,1HNMR and MS. Synchronously, their melting point, solubility, thermal stability and electrochemical window were determined. The results show that the ionic liquids exhibit high purity, excellent thermal stability and wide electrochemical stability interval.The extractive experiment of rhodamine B with hydrophobic ILs:1-butyl-3-H-benzimidazolium hexafluorophosphate(A5), 1-benzyl-3-H-benzimidazolium hexafluoro-phosphate(B5) and 5-nitro-1-butyl-3-H-benzimidazolium hexafluorophosphate(C5) were investigated respectively. The experiment results indicate that the extraction equilibrium can reach after an hour. Excessively high temperature would result in the decrease of extracting efficiency. The value of pH plays a great role in the removel of Rhodamine B. The optimal extraction environment is neutral or weak acid. Under the coequal conditions, the extracting efficiency of the ILs is better than imidazolium ILs.The extractive desulfurization performance of the ILs:5-nitro-1-butyl-3-H-benzimidazolium bromine(C2),5-nitro-1-butyl-3-H-benzimidazolium tetrafluoroborate (C4),5-nitro-1-butyl-3-H-benzimidazolium hexafluorophosphate(C5), were investigated respectively. With benzothiophene(BT)/octane as the model systems, the extration conditions and their effect on desulfurization efficiency were estimated. Experimental results confirmed that the desulfurization rate of C5 and C4 is higher than C2. The desulfurization rate of single stage extraction of C5 with a mass ratio 1:1 was 56.9%. Keywords:benzimidazole, ionic liquids, aromatic compounds, extraction,...