The Study On Absorption Of Halogenated Hydrocarbons And Aromatic Vocs By Ionic Liquids Complex Absorbent

Volatile Organic Compounds（VOCs）which exist as steam in the air are toxic,carcinogenic and harmful to humans owing to longterm exposure.As a precursor to PM?2.5,VOCs are also a major factor to produce smog.The VOCs have been hot spot and are extremely urgent to be dealed with at home and abroad because of its harmfulness.Absorption is particularly important for the high economic value of material in VOCs.As kinds of green solvents,ionic liquid has the advantages of strong solubility,easy control,easy recovery and high thermal stability,and is widely used in absorption,synthesis and extraction.Aiming at the disadvantage of high viscosity of ionic liquid,polyethylene glycol200（PEG200）is adopted as the cosolvent to absorb halogenated hydrocarbons and aromatic mixed VOCs emitted by petrochemical industry.Seven kinds of ionic liquids and PEG200were selected to form a new type of absorbent.The feasibility of PEG200 as a cosolvent was verified by the measure of saturated absorption and initial absorptivity.The results showed that[EMIM][Cl]-PEG200 complex absorbent had better absorption on dichloromethane.The initial absorptivity of dichloromethane by[EMIM][Cl]-PEG200complex absorbent can reach 85%under the experimental conditions.In addition,studies have shown that the absorption of ionic liquid complex absorbent remains basically unchanged with the increase in the number of reuse.By quantum chemistry calculation,the effect of ionic liquid structure on the interaction between ionic liquid and dichloromethane was investigated in microscopic view by Gaussian at the B3LYP/6-31G+（d,p）basis set in DFT theory.The result of calculations verified experimental rules that the cation of ionic liquid have minor effect on absorption effect compared to ionic liquid anion which is a dominant role in the process of absorption and the absorption effect along with the increase of carbon number cation alkyl side chains is reduced.For the mixed waste gas of dichloromethane and benzene,by the comparison of the absorption effect of different kinds of ionic liquids complex absorbents on mixed waste gas,it is found that the complex absorbent composed of[HMIM][Cl]and PEG200 has better absorption effect on mixed waste gas of dichloromethane and benzene.The various influence factors of complex absorbents in the absorption of mixed waste gas were investigated.Under the experimental conditions of methanol and benzene inlet gas concentrations of 20,000?mg·m^-3and 5,000?mg·m^-3,inlet flow rate of 0.2?L·min^-1and temperature of 298.15?K,the initial dichloromethane and benzene absorptivity of 40?g complex absorbent which the mass fraction of ionic liquid is 60?%reached 85?%and87?%.The feasibility of recovery and utilization of complex absorbent was verified by experiments of regeneration and cyclic absorption.It was proved by quantum chemistry calculation that the interaction energy between ionic liquid and dichloromethane was weakened by benzene.That is,during the absorption process,the competition between dichloromethane and benzene leads to the absorption effect of the complex absorbent on the mixed exhaust gas is less than that of the single component.The complex absorbent was characterized by¹H NMR and FT-IR before and after absorption.The results show that the complex absorbent has a hydrogen bond when it interacts with dichloromethane and benzene.