Investigations On Mass Transfer At The Interface Of Ionic Liquid/aqueous Phase By Optical Waveguide Technique

The mass transferring behaviors of protein at the interface of ionic liquid and aqueous phase are investigated in the present work by adopting liquid core optical waveguide technique.In the first part of the thesis, a brief review is given to the following issues:the properties of ionic liquids, the applications of ionic liquids in the field of extraction/separation, the principle of total internal reflection and evanescent wave and their applications in liquid/liquid interface studies, and the applications of liquid core waveguide technology in analytical chemistry.In the second part of the thesis, an optical waveguide system is fabricated by using ionic liquid as the core. The optical path of total internal reflection is demonstrated by the addition of a fluorescent dye Rhodamine 6G into the ionic liquid phase. At the same time, the feasibility and practical applicability of this optical waveguide system is validated by monitoring the extraction process of dye EBT at the liquid/liquid interface. On this basis, the constructed liquid core waveguide system is adopted for the study of mass transferring of hemoglobin (Hb) at the interface of ionic liquid and aqueous phase. Afterwards, the extraction of Hb by ionic liquids 1-butly-3-methylimidazolium hexafluorophosphate(BmimPF6) and 1-3-two-butlyimidazolium hexafluorophosphate(BBimPF6) have been studied. The effect of the changes of micro-environment on the adsorption spectra of Hb are also investigated. The results indicated that the fastest mass-tranferring rate is observed at an acidic condition, suggesting that electrostatic interaction between Hb and ionic liquid is not the driving force for the transferring of Hb into the ionic liquid phase. Meanwhile, it has been proven that transferring of Hb into the more hydrophobic ionic liquid BBimPF6 is faster when compared to that observed for the ionic liquid BmimPF6. This indicated that the hydrophobic interaction between ionic liquid and Hb plays an important role on the mass transferring of Hb during the extraction process. The UV-vis spectra of Hb obtained by optical waveguide system at different pH values suggest that the change of micro-environment pose great influence on the characteristic absorbance of Hb. The coordination of Hb with cationic moiety of the ionic liquid leads to a red shift of the maximum absorbance.