Study On Thermodynamic Properties Of Ionic Liquid Solution And Preparation Of Electrochemical Co Gas Sensor

Compared with traditional solvents,ionic liquids（ILs）show certain advantages in chemical separation as a green solvent.The thermodynamic properties of ionic liquid solutions can provide a theoretical basis for the application of ionic liquids in the chemical separation process,as well as basic data for the thermodynamic prediction model.In addition,the advantages of electrochemical gas sensor,such as small volume,high sensitivity and convenient real-time detection,make it have a wide application prospect in gas concentration detection.The excellent electrochemical performance of ionic liquid has attracted attention as a new electrolyte in electrochemical gas sensor.In this paper,the ILs 1-ethyl-3-methylimidazolium dimethyl phosphate（[EMIM][DMP]）and 1-butyl-2,3-dimethylimidazolium thiocyanate（[BMMIM][SCN]）were synthesized,and the two ILs were used as stationary phases to prepare gas chromatography packed columns.The infinite dilution activity coefficients(^∞₄))of a series of organic compounds in ionic liquids[EMIM][DMP]（T=323.15-363.15 K）and[BMMIM][SCN]（T=313.15-363.15 K）were determined by gas chromatography and gas-liquid partition coefficient（_L）at corresponding temperature.By associating^∞₄)and T,partial molar excess enthalpy(?₄)^E,∞),the entropies(₀1))?₄)^E,∞),and iibbs free energies（_）^E?₄,^∞)at T=298.15 K were obtained.Based on the linear free energy model（LFER）,the_L prediction models of two ILs were established by multiple regression of_L experimental values.The solubility parameters of the two ILs were estimated according to Hildebrand Scatchard regular solution theory and Flory equation.The infinite dilution selectivity(^∞₄5)))of the two ILs were obtained for several difficult separation systems at 323.15 K with^∞₄).The results show that the two ILs have good separation effects on alkane/aromatic hydrocarbon,olefin/alcohol and aromatic/alcohol systems.The^∞₄5))of hexane/benzene and cyclohexane/benzene systems and benzene capacity（6）^∞₅))at T=323.15 K were compared with the data of the ILs containing[EMIM]⁺cation or[SCN]^-anion in the literature.The results show that for the same type of cations,the shorter the substituent chain length,the better the^∞₄5))of ILs.The application of IL as electrolyte in electrochemical CO gas sensor is also discussed in this paper.The two electrode and three electrode sensor shell models were designed,and the signal amplification circuit is used to detect the performance of the sensor.The membrane electrode was prepared by screen printing method.The effects of printing additives such as catalyst,binder,dispersant and surfactant in the slurry on the performance of the sensor were investigated.The effects of electrode printing material,filler material,membrane electrode sintering procedure,water washing process,electrolyte addition and aging time were also studied.The ionic liquids of 1-propyl-3-methylimidazole bromide and 1-octyl-3-methylimidazole chloride were selected as electrolyte.Compared with the traditional sulfuric acid solution electrolyte,the application of ILs as electrolyte in electrochemical CO gas sensor was preliminarily explored.