Removal Characteristics And Mechnism Of Dichloromethane Photodegradation By Irradiation Of Vacuum Ultraviolet

Air pollution is currently one of the most significant environmentalproblems,The inportant link to improving quality of the reginal air iscontrol of the volatile prganic compounds (VOCs). Using Ultraviolet (UV)oxidation as biotrickling filter (BTF) pretreatment methods to purify theVOCs, Enhanced performance of particularly poor water soluble anddifficult biodegradable VOCs has become a new technology in recentyears.In this paper, the vacuum ultraviolet (VUV) technology was used as atreatment for the removal of gaseous dichloromethane (DCM). Researchon the removal characteristics and mechanism were carried outsystematically. Under the same process conditions The DCM removalefficiency by the 185nm lamp are better than by the 254nm and 365nmlamp.The DCM removal efficiency increased from 8.58% to 80.79% withthe EBRT extending from 9s to 90s. The DCM removal efficiency showedthe tendency of declining with the increase in inlet concentration, but theabsolute removal amount of DCM increased. The DCM removal efficiency of photolysis is best under the inlet concentration of 200mg·m^-3,EBRT 90s and relative humidity 75%⁸5%.Under the same conditions, the wavelength of 185 nm was moreeffective than that of 254 or 365 nm for the removal of DCM. Based onthe identified intermediates (HCl, acids, CO₂, H₂O etc.), the combined roleof photolysis, ozone photodegradation and HO·photodegradation wasproposed during the removal of DCM. Some biodegradable compoundsgenerated by the photodegradation provided a possibility for theapplication of integrated VUV-biological technology.