The Study On Dispersion Behavior Of Ionic Liquid Supported On Active Carbon

Ionic liquids possessing an array of properties: negligible vapor pressure,relatively low viscosity,thermal stability,and relatively high ionic conductivity,have strongly attracted scientific attention.A variety of new exciting applications of ILs have been developed in some industries continuously,such as gas separation,catalysts,materials synthesis.However,there are few studies on the distribution performance of SILP.Especially,the distribution behavior of supported ionic liquids on actived carbon has hardly been reported,due to its complex surface chemistry and disordered pore structure.This study includes two aspects: the effect of surface chemistry of activated carbon to the distribution behavior of SILP;and the physical parameters of ionic liquids.The main work and results of this article are as follows:1.Different surface oxygen content of active carbon was obtained by using concentrated nitric acid solution and thermal treatments under different temperatures using this method.The various oxygen content will lead to different density of ? electrons on the surface of the activated carbon.The results prove that this method used in this work can successfully modify the surface ?-electron density of activated carbon without influencing the textural properties.2.The ionic liquid used in this work is [BMim]Cl loaded onto the prepared activated carbons,and the SILP materials were performed using the BET characterization technique.It was found that ionic liquids are not uniformly distributed on the surface of activated carbon.The ionic liquids loading and the surface chemical properties of activated carbon influence the dispersion behavior of ionic liquids,which result to different degrees of blocked porosity.This article found that the distribution of ionic liquids on the surface of activated carbon is more uniform with the less surface oxygen content.3.This article explores the stability of SILP materials in water.The result of characterization of washed SILP materials suggested that the ionic liquid loaded on the carbon materials was not washed completely,the more amount of the ionic liquid remained on the surface of activated carbon with less suface oxygen content.We discovered that supported IL was not easily washed off supported on activated carbon with low concentration surface oxygenated groups,because the oxygen-free supports have a high density of free ?-electrons and the H atom on the C2 position of the acidic cation in the IL structure forms CH-? bond with the surface ?-electrons on carbon materials.These results showed that the formation of CH-? hydrogen bond between the ionic liquid and carbon materials with high free ?-electrons can enhance the dispersion of ionic liquid on the surface of the support.3.A series of SILP materials with different ionic liquid loadings,viscosities,and space structures were prepared to investigate the effect of physical properties on the distribution behavior of supported ionic liquids.The characterization result showed that:1)the degree of blocked porosity increases first and then decreases by ionic liquid loading increased;2)The distribution of IL on surface of active carbon is more uniform with greater viscosity of the ionic liquid for anions with weaker electronegativity;3)The ionic liquid with longer alkyl side chain can block the pore of carbon easier,due to the greater steric effect.