title: A chemiluminescence-based continuous flow aqueous ozone analyzer using photoactivated chromotropic acid.
abstract: Ozone has become the oxidant of choice for water disinfection, especially in large water treatment facilities. This paper describes a fast and sensitive method for the determination of ozone content by reaction with photoactivated chromotropic acid (CA, 4,5-dihydroxynaphthalene-2,7-disulfonic acid), which results in intense chemiluminescence (CL). Freshly ozonated water from a recirculating ozonizer/reservoir is injected into a carrier stream of deionized water in the flow-injection mode. This flow mixes with a stream of photoactivated CA solution in a spiral cell placed directly on top of an inexpensive miniature (8mm diameter active area) photomultiplier tube (PMT). Alkaline CA is photoactivated by passing it through a FEP-Teflon((R)) coil (residence time approximately 50s) wrapped around a 1W UV lamp emitting at 254nm; without photoactivation, the signal is approximately 70-fold lower. The S/N=3 limit of detection for aqueous ozone is 3mugl(-1) and good response slope is obtained up to an ozone concentration of 1.4mgl(-1), the highest that could be made in this study. The response obeyed a quadratic equation with r(2)=0.9984. No interference from permanganate ion is observed. The proposed system was applied to the monitoring of ozonation status of a playa lake water that exhibited significant ozone demand.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA.
authors.forename: Toshio
authors.initials: T
authors.lastname: Takayanagi
authors.forename: Purnendu K
authors.initials: PK
authors.lastname: Dasgupta