Kinetics of the aqueous-phase reaction between ozone and 2,4,6-trichlorophenol

✍ Scribed by Edward B. Rinker; Sami S. Ashour; Michael C. Johnson; Gregory J. Kott; Robert G. Rinker; Orville C. Sandall

• Publisher: American Institute of Chemical Engineers
• Year: 1999
• Tongue: English
• Weight: 112 KB
• Volume: 45
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690450815

✦ Synopsis

A wetted-sphere absorber was used to measure absorption rates of ozone into aque-( ) ous-buffered solutions of 2,4,6-trichlorophenol TCP . Gas consisting of approximately 2.5% ozone in oxygen was contacted with aqueous-buffered TCP solution flowing o®er a sphere in a laminar liquid film. Absorption data were obtained by measuring the change in the liquid-phase concentration of TCP from the inlet to the outlet of the absorber. A rigorous numerical model for this diffusionrreaction process was used to analyze the absorption data to determine the second-order rate constant of the reaction between ozone and TCP at 15 ᎐ 35ЊC and pH 2 and 7. The kinetic data indicate that the rate-limiting step for the reaction of aqueous TCP with ozone is the same at pH 2 and 7. Four reaction products that occur early in the reaction of ozone with aqueous TCP ( ) were identified by GCMS, including: 2,3,4, 4, DCC , 2, and 2, Only DCHQ and DCQ occurred in significant concentrations. O®er the pH range of 2 to 5, both DCHQ and DCQ were detected in the reacted solutions, while for pH 6 and 7 only DCHQ was detected. Carbon-13 NMR analysis shows that o®er longer ozone exposure times short-chain carboxylic acids are the dominant species in the reacted TCP solutions.