Preparation Of Polyaniline Electrode And Its Application In Electrochemical Synthesis Of Benzoic Acid

Organic electrochemical synthesis uses electrons as oxidation-reducing agent to complete the synthesis of organic compounds through reactants gain and loss electrons on the surface of the electrode.It has the characteristics of good selectivity,high yield,mild conditions,less side reaction effects and less pollution.Therefore,the organic electrochemical synthesis,to a great extent,reduced the environmental pollution caused by the traditional organic synthesis process,making it a popular subject in the twenty-first Century.It is called "green synthesis" technology and is used in many organic synthesis.In the organic electrochemical synthesis,the electrode material is a special functional material,which not only involves the energy consumption in the reaction process,but also directly affects the yield and product quality of the reaction.Therefore,in the process of organic electrochemistry synthesis,it is very important to prepare and select suitable electrode materials.In this paper,the polyaniline electrode with good conductivity and excellent corrosion resistance was prepared by electrochemical method(cyclic voltammetry/constant potential method).It is used as a highly active anode material for the synthesis of benzoic acid by electro oxidation toluene.The electrochemical synthesis of benzoic acid is carried out based on the characteristics of organic electrochemistry synthesis.The properties of the polyaniline electrodes were investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier Transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),thermogravimetric(TGA),X-ray photoelectron spectroscopy(XPS),Raman spectroscopy,electrochemical impedance spectroscopy(EIS),and polarization curves(Tafel).The reaction products were qualitatively and quantitatively analyzed by UV and gas chromatography.The main contents of this paper can be summarized as follows:(1)PANI/PDA was prepared by electrochemical method(cyclic voltammetry/constant potential method)using graphite as electrode material matrix.Through the dopamine modified graphite,the main function of the dopamine layer is to make the polyaniline film have a good bonding force with the graphite matrix,and improve the corrosion resistance of the electrode.The prepared PANI/PDA was used as anode material to oxidize toluene to benzoic acid.Compared with pure graphite and PANI as anode,the yield of benzoic acid and the conversion rate of toluene were the highest,40.1%and 98.7%,respectively.This is because PANI/PDA can increase the ability to capture and react to the organic molecules during the synthesis of benzoic acid,ensure the high efficiency of the reaction,which is beneficial to the improvement of the synthesis efficiency.(2)The carbon fiber cloth(CC)with good electrical conductivity and high tensile strength is used as the substrate of the electrode material.First,CC is modified with dopamine to obtain good adhesion,and then the polyaniline film is grown on the modified CC surface by cyclic voltammetry.Finally,the conductivity and corrosion resistance of the material were enhanced by adding graphene by cyclic voltammetry.In the end,CC/PANI/G was prepared.CC/PANI/G is used as the anode for the synthesis of benzoic acid as the electrochemical oxidation of toluene.Compared with the CC as the anode,the amount of hydrogen produced with the cathode increases 120.7 times,the yield of benzoic acid and the conversion rate of toluene are increased to 41.7%and 99.9%respectively.This is because CC/PANI/G has special electrical conductivity and electrochemical redox properties after adding graphene.The good electron mobility of graphene will rapidly transfer the electrons generated to the circuit,and toluene can be oxidized to benzyl alcohol,benzaldehyde and benzoic acid through the "oxidation unit" of polyaniline,thus ensuring the favorable oxidation of toluene.(3)A polydopamine film(PDA)was coated on carbon steel plate by cyclic voltammetry,and then GO/PDA composite membrane was prepared by impregnation method.Polydopamine has strong adhesion.It can be attached to the surface of carbon steel by electrochemical method,and it can be firmly combined with GO.The electrochemical corrosion analysis of GO/PDA shows that compared with carbon steel plate and PDA,GO/PDA has the highest impedance value after soaking 24 h in 3.5 wt%NaCl solution,reaching 1.4 x 10~4?,and having a corrected corrosion potential and smaller corrosion current density,so GO/PDA has better corrosion resistance.Because the surface of GO contains a large number of active groups,it can increase the reactive activity of the electrode,and GO/PDA also has excellent corrosion resistance.It can be used as the anticorrosive electrode material with electrochemical synthesis,which has the guiding significance for the preparation of electrode materials with more excellent corrosion resistance.