Simulation Study On Henry's Constant And Interaction Between Ils And Typical Vocs

As one of the chief culprits for air pollution,volatile organic compounds(VOCs)derive from a wealth of sources and have a great hazard.However,most of them have economic value.So,the research of recovery processing has not only environmental significance but also economy profit.Absorption method has many advantages such as low degree of operation difficulty,high technical maturity,wide range of application,easy to industrialize,which make it become the one of the heated topics of recovery technology.However,the selection of absorbent has been the important constraints factors in the development of absorption method due to the problems of absorption capacity,secondary pollution and so on.Ionic liquids own a lot of special characteristics such as extremely low volatility,high degree of designable ability and so on.All these features make it be worth spreading application but we have to face the challenge of prediction and synthesis for suitable ionic liquids.According to the problems mentioned above,this paper studied issues listed below:1.We selected the dichloromethane as a typical representative of VOCs and screen the suitable absorbent among 4387 ionic liquids according to ADI(Absorption Desorption Index)and Henry's constant.All the ionic liquids were composed of 107 cationic and 41 anionic species.We chose[triethylsulfonium][acetate]as a suitable ionic liquid solvent with the further consideration of melting point,viscosity and consumption energy of regeneration.In this article,we also researched relationships between henry's constant and ionic characteristics such as acid-base property of hydrogen bond,volume of ions,number and position of alkyl substituent in cation.The results showed:ADI and henry's constant mainly depended on anion.Henry's constant decreased with the increase of hydrogen bond basicity of anion and volume of cation.In the view of structure-function relationship,Henry's constant increased with the increasing number of alkyl substituent in cation.Besides,henry's constant would decrease when acid site in cation was substituted by methyl substituent.Compared with henry's constant,the change of ADI showed adverse tendency.2.We chose the[Bmim][Ac]and[Bmim][PF6]as representative of ionic liquids and used quantum chemistry calculation to study interaction between ILs and dichloromethane in the microcosmic.Meanwhile,influence of water on ILs-CH2CL2 system was analyzed.The results showed:dichloromethane could form H-bond with different anions.Besides,the number of H-bond and it strengths depended on the combination factors of electrostatic attraction and steric hindrance.The order of interaction energy is CH2CL2-[PF6]-<CH2CL2-[BF4]-<CH2CL2-[Br]-<CH2CL2-[CL]-<CH2CL2-[Ac]-.We found that the interaction between dichloromethane and ILs to interaction between cation and anion in ILs ratio is too low.This means it is unsuitable to predict solubility of dichloromethane in ILs systems using the solubility model which is based on regular solution theory.What's more,interaction strength would be weakened when water was introduced into the ILs-CH2CL2 systems.3.In order to promote wider application,we tried to propose a new correction factor for two systems:1.Binary systems composed by dicationic ionic liquids.2.Multicomponent system composed by ionic liquids or conventional solvents.The results showed:for binary systems composed by dicationic ionic liquids,correction factor was 1/3;for multicomponent system composed by ionic liquids and conventional solvents,correction factor was related with mixing ratio.For multicomponent system composed by different ionic liquids,correction factor was 1/2.