Addition of corrosion promoters, such as sodium and potassium chloride, accelerated TNT degradation during water treatment using zerovalent zinc and iron. It was theorized that corrosion promoters could be used to accelerate electron generation from metallic species, create new reactive sites on the surface of metals during contaminated water treatment, and minimize passivating effects. The surface area normalized pseudo-first-order rate constant for the reaction of zerovalent zinc with TNT in the absence of KCl was 1.364 L x m(-2) x h(-1). In the presence of 0.3 mM and 3 mM KCI, the rate constant increased to 10.5 L x m(-2) x h(-1) and 51.0 L x m(-2) x h(-1), respectively. For the reaction with zerovalent iron and TNT, the rate constant increased from 6.5 (L/m2 x h) in the absence of KCl to 37 L x m(-2) x h(-1) using 3 mM KCl. The results demonstrate that chloride based corrosion promoters enhance the rate of TNT degradation. The in-situ breakage of the oxide layer using corrosion promoters was applied as a treatment to maintain the long-term activity of the metallic species. Zinc maintained a high reactivity toward TNT, and the reactivity of iron increased after 5 treatment cycles using 3 mM KCI. Zinc and iron scanning electron micrographs indicate that TNT degradation rate enhancement is caused by the pitting corrosion mechanism.

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The present research concerns mechanism and rate of reaction between dissolved ozone and phenol in homogeneous solutions. The stopped-flow technique was employed to obtain absorbances during reactions; the kinetic experiments were conducted at temperatures varying from 5" to 35OC in aqueous solutions with pH values ranging from 1.5 to 5.2.The kinetic data indicated that the absorbance of a mixed solution increased rapidly in the very early portion of the reaction and then declined slowly in the remaining period. The rate of reaction in the early period was first order with respect to both phenol and ozone concentrations. The rate constant increased with pH value and temperature, and an activation energy of 5.74 K cal/mole was obtained. Further tests showed that the dissolved ozone was consumed completely in the first period and that in the second period the intermediate products were decomposed without depletion of ozone. Catechol, o-quinone, hydroquinone, oxalic acid, humic acid, and a dimer were identified from mass spectra as products of the ozonization reaction.A free radical mechanism, with initiation of an electrophilic reaction for the formation of catechyl radical, has been proposed to explain the experimental data for phenol-ozone reaction in aqueous solutions. According to the proposed mechanism, the reaction path through the attachment to ortho position is much more favorable compared with that through the paraposition because of geometric advantage, though quinones and hydroxyphenol can be formed through parallel paths. The products of reaction detected in this research, therefore, are accountable by this mechanism. A rate equation derived on the basis of this mechanism also agrees well with that observed from the kinetic experiments. J. L. WEEKS, JR. Department of Chemical EngineeringMississippi State University Mississippi 39762Ozonization has been considered as a promising method for tertiary treatment of liquid industrial wastes. Although ozone injection technique has been applied in several industrial plants for treatment of phenolic waste, scientific information concerning the process is inadequate, In the fore, the stopped-flow technique was applied in this research to study kinetics of ozonization of phenol in homogeneous solutions. Influences of pH value and temperature on the reaction rate also were investigated. Products of the reaction were identified utilizing the technique of gas chromatography and mass spectrometry. On the basis of the experimental results, a mechanism of the reaction between phenol and &solved Ozone in aqueous solutions has been suggested. past studies, experiments were conducted using contacting reactors, and the kinetic data were obscured by influences of mass transfer on rate measurements. There- CONCLUSIONS AND SIGNIFICANCERapid reaction between dissolved ozone and phenol in aqueous solutions was studied successfully utilizing the stopped-flow technique. Absorbances measured during the early life of the reaction (as short as a few milliseconds) were important in de...

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This research investigates the kinetics of traditional ozonation and peroxone oxidation of ammonia in alkaline solutions. The ozonation reaction is governed by the direct oxidation of ammonia with ozone molecules, and the overall kinetics is second order, with first order each in ozone and ammonia. The reaction rate increases slightly with temperature, and at 25 °C, the overall rate constant varies from 12.3 to 27.0 1/Ms as the pH increases from 8 to 10. In the presence of hydrogen peroxide, the peroxone oxidation is controlled mainly by the formation of hydroxyl radical and its subsequent radical reactions. The depletion rate of ozone is first order with respect to both concentrations of ozone and hydrogen peroxide but is nearly independent of the ammonia concentration. The overall rate constant increases from 5860 to 133 000 1/Ms in the pH range of 8−10 at 25 °C, indicating that the rate increases with the hydroxyl ion concentration of the exponent of 0.71. The destruction rate of ammonia depends on concentrations of various species, and for wastewaters containing high concentrations of ammonia, the peroxone oxidation process can be effective and economical to achieve a high efficiency for ozone utilization.