The Research Based On Poly Ionic Liquids For Electrochemical Catalysis Of Phenols

Phenolic compounds are the common used industrial material, which are highly toxic, wide source and complicated organic matter composition and listed as the first control contamination. Ominously, the effective degradation of phenolic compounds is now challenging due to their compact structure and good chemical stability. Prominent among the various techniques to deal with the phenol-bearing wastewater, electrochemistry has been considered as one kind of most prospective methods with its low-energy washing, efficiency and less polluting. Meanwhile, poly ionic liquid, with its excellent electrochemical performance, has also become one of the best catalytic materials for electrochemical catalysis of phenols.Electro-catalytic materials, poly ionic liquid （poly[ABMI]PF₆） and poly ionic liquid-nano titanium dioxide complex （poly[ABMI]PF₆-TiO₂） were prepared by electrochemical polymerization in this paper. Besides, the electrochemical behaviors of phenol, HQ and CC on the modified electrode （poly[ABMI]PF₆/Au and poly[ABMI]PF₆-TiO₂/Au） were systemically studied. The detailed research contents are as follows:（1） A new type of ionic liquid （ABMI） has been designed and synthesized by two-step process with imidazole, nitrobenzyl chloride and 1,4-dibromobutane as raw materials. The structure was identified by IR and 1H-NMR and 13C-NMR spectra. Poly[ABMI]PF₆/Au was prepared by chronoamperometry, the current transient curve indicate that the ionic liquid ABMI is deposited on Au electrode in three-dimensional instantaneous nucleation. Poly[ABMI]PF₆-TiO₂/Au was prepared by chronoamperometry, the current transient curve indicate that the ABMI-TiO₂ is also deposited on Au electrode in three-dimensional instantaneous nucleation. A comparison of cyclic voltammetry curves between ABMI and ABMI-TiO₂ show that the polymer growth of ABMI and ABMI-TiO₂ on Au electrode should be completely follow the same pattern. The microstructure of poly[ABMI]PF₆ and poly[ABMI]PF₆-TiO₂ were analyzed by means of SEM.（2） The electrochemical behavior of poly[ABMI]PF₆/Au measured by cyclic voltammetry （CV） and electrochemical impedance spectroscopy （EIS） showed that the transfer ability of electron in poly[ABMI]PF₆ layer is good. The electrochemical behaviour of phenol on poly[ABMI]PF₆/Au electrode and Au electrode are studied by CV. And the electrochemical results show that the irreversible oxidation with one electron and one proton transfer of phenol on the poly[ABMI]PF₆/Au electrode was increased significantly compared with that on the bare Au. Besides, the effects of buffer solutions, pH, accumulation time and potential, scanning rate and temperature were also investigated, and the best technique parameter was provided. The analysis of all the oxidation peak current with the scanning rate showed that the phenol electrode reaction occurred on the electrode was controlled by diffusion when the scanning rate is 0.02～0.1 V/s; the phenol electrode reaction occurred on the electrode was controlled by adsorption when the scanning rate is 0.2～0.9 V/s. The relationship between oxidation peak current and temperature （25～45 ℃） showed that the reaction apparent activation energy of phenol on poly[ABMI]PF₆/Au electrode is 30.74 kJ’mol^-1. The linear relationship between oxidation peak currents and concentrations of phenol held in wide ranges, which can indicate that the poly[ABMI]PF₆/Au could be applied as a good candidate material for electrochemical catalysis of phenols.（3） The electrochemical behavior of poly[ABMI]PF₆-TiO₂/Au measured by CV and EIS showed that the transfer ability of electron in poly[ABMI]PF₆-TiO₂ layer is good.The electrochemical behaviors of HQ and CC on poly[ABMI]PF₆-TiO₂/Au, Au, poly[ABMI]PF₆/Au and TiO₂/Au electrode have been studied by CV and differential pulse voltammetry （DPV）.The results showed that the reversible oxidation-reduction reactions of HQ and CC on the poly[ABMI]PF₆-TiO₂/Au electrode increased significantly compared with that on the other electrodes.Effects of buffer solutions,pH, scanning rate and temperature were also investigated, and the best technique parameter was provided. The analysis of all the redox peak current with the scanning rate showed that the HQ and CC electrode reaction occurred on the electrode was controlled by diffusion when the scanning rate is 0.05 V/s. The number of electron transfer was equal to the number of protons （n=m=2） for both HQ and CC, and diffusion coefficient of HQ and CC is 3.591×10-7cm²/s and 1.913×10-6 cm²/s with the effective area of poly[ABMI]PF₆-TiO₂/Au electrode A=0.1073 cm².The relationship between diffusion coefficient and temperature （25～45 ℃） showed that the reaction activation energy of HQ and CC on poly[ABMI]PF₆-TiO₂/Au electrode is 49.39 kJ·mol^-1 and 34.93 kJ·mol^-1, respectively. The linear relation-ship between catalytic currents and concentrations of HQ and CC held in wide ranges,which can indicate that the poly[ABMI]PF₆-TiO₂/Au could be applied as a good candidate material for electrochemical catalysis of HQ and CC.