Photocatalytic Oxidation of Gaseous 2-Chloroethyl Ethyl Sulfide over TiO sub(2)

• Published in: Environmental science & technology Vol. 37; no. 15; pp. 3448 - 3453
• Main Authors: Martyanov, IN, Klabunde, K J
• Format: Journal Article
• Language: English
• Published: 01.08.2003
• Subjects: 2-chloroethyl ethyl sulfide; titanium dioxide
• ISSN: 0013-936X

Photocatalytic oxidation of gaseous 2-chloroethyl ethyl sulfide (2-CEES, ClCH sub(2)CH sub(2)SCH sub(2)CH sub(3)) over TiO sub(2) illuminated with UV light and maintained at 25 or 80 degree C in air has been investigated. 2-CEES was found to suffer progressive oxidation to yield ethylene (CH sub(2)CH sub(2)), chloroethylene (ClCHCH sub(2)), ethanol (CH sub(3)CH sub(2)OH), acetaldehyde (CH sub(3)C(O)H), chloroacetaldehyde (ClCH sub(2)C(O)H), diethyl disulfide (CH sub(3)CH sub(2)S sub(2)CH sub(2)CH sub(3)), 2-chloroethyl ethyl disulfide (ClCH sub(2)CH sub(2)S sub(C)H sub(2)CH sub(3)), and bis-(2-chloroethyl) disulfide (ClCH sub(2)CH sub(2)S sub(2)CH sub(2)CH sub(2)Cl) as the main primary intermediates, and water (H sub(2)O), carbon dioxide (CO sub(2)), sulfur dioxide (SO sub(2)), surface sulfate ions (SO sub(4) super(2-)), and hydrogen chloride (HCl) as the final products. Trace concentrations of gaseous 2-chloroethanol (ClCH sub(2)CH sub(2)OH), ethanesulfonyl chloride (CH sub(3)CH sub(2)SO sub(2)Cl), ethyl thioacetate (CH sub(3)CH sub(2)SC(O)CH sub(3)), and considerable amounts of acetic acid (CH sub(3)C(O)OH), crotonaldehyde (CH sub(3)CHCHC(O)H), methyl acetate (CH sub(3)C(O)OCH sub(3)), and methyl formate (CH sub(3)OC(O)H) were also detected in the gas phase during the photooxidation conducted at 80 degree C. Increase in temperature from 25 to 80 degree C accelerates formation of gaseous ethanol, acetaldehyde, chloroacetaldehyde, diethyl disulfide, 2-chloroethyl ethyl disulfide, and bis(2-chloroethyl) disulfide but suppresses ethylene and chloroethylene production at initial stages of the process. Some aspects of the possible reaction mechanism leading to this wide array of intermediates and final products are discussed.