HR: 1340h
AN: H33E-1686    [Abstracts]
TI: Formation Of Perchlorate By Ozonation Of Aqueous Oxy-chlorine Anions: An Insight To Natural Perchlorate Formation
AU: * Rao, B
EM: balaji.rao@ttu.edu
AF: Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, Texas 79409-1023, Lubbock, TX 79409-1023, United States
AU: Jackson, A
EM: andrew.jackson@ttu.edu
AF: Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, Texas 79409-1023, Lubbock, TX 79409-1023, United States
AU: Kang, N
AF: Division of Metrology for Quality Life, Korea Research Institute of Standards and Science, Daejeon, 305340, Korea, Republic of
AU: Redder, A
EM: aaron.redder@ttu.edu
AF: Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, Texas 79409-1023, Lubbock, TX 79409-1023, United States
AB: Perchlorate (ClO₄^-) is a natural and anthropogenic contaminant of increasing concern. Natural perchlorate was first identified in Chilean nitrates from the Atacama dessert over 100 years ago. However, only in the last two years has the occurrence of natural perchlorate been seriously considered as a potential exposure source. Although there has been considerable research effort in understanding the occurrence, remediation, and impact of ClO₄^- in the environment, relatively little information is available regarding the mechanism(s) responsible for ClO₄^- formation. Perchlorate productions from ozone oxidation of chlorine and oxy- chlorine anions (Cl^-, OCl^-, ClO₂^-and ClO₃^-) were conducted in continuous flow reactors at constant ozone concentrations (approximately 6 mg L^-1) and at varying concentrations of chlorine materials (ranging from 10 to 1000 mg L^-1). Sub samples from both the main reaction flask and alkaline trapping flasks were taken over varying time intervals and the concentrations of oxy-chlorine anions including ClO₄^- were measured using various ion chromatographic methods whereas OCl^- was determined iodometrically using the spectrophotometer. The experiment time ranged from 6 hrs to 7 days depending on the rate of decomposition of the reactants. Results indicate that ClO₄^- is readily formed during the ozonation of ClO₂^- and OCl^- solutions (maximum conversion of 2.7 %) whereas the Cl^- and ClO₃^- solutions produced relatively lower quantities of ClO₄^- ( maximum conversion of 0.02 %) . Further the presence of ClO₂^- in the initial OCl^- solution is suspected to significantly contribute the total ClO₄^- generated augmenting the role of ClO₂^- in ClO₄^- formation as mentioned in recent study on the photochemical reactions of oxy-chlorine anions.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0335 Ion chemistry of the atmosphere (2419, 2427)
DE: 0792 Contaminants (0432)
SC: Hydrology [H]
MN: 2007 Fall Meeting