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...

Theoretical effects of parallel reversible chemical reactions on the rate of mass transfer are investigated in this paper. On the basis of the film theory, an analytical equation has been derived for gas absorption accompanied by first‐order parallel rversible reactions. Analytical approximate equations have been developed and finite difference techniques applied to study the enhancement of mass transfer by second‐order complex reactions. Results of this study indicate that when the diffusion is accompanied by second‐order parallel reactions, the mass transfer rate increases with the concentration of the liquid reactant in the bulk, and approaches that of diffusion and first‐order parallel reactions if the product of the diffusivity and bulk concentration of the liquid reactant is much larger than that of the gas reactant.