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This study investigates the ozonation of 2-mercaptothiazoline (2-MT). The 2-MT is one of the important organic additives for the electroplating solution of the printed wiring board industry and has been widely used as a corrosion inhibitor in many industrial processes. It is of concern for the aquatic pollution control especially in the wastewaters. Semibatch ozonation experiments in the completely stirred tank reactor are performed under various concentrations of input ozone. The concentrations of 2-MT, sulfate, and ammonium are analyzed at specified time intervals to elucidate the decomposition of 2-MT during the ozonation. In addition, the time variation of the dissolved ozone concentration (CALb) is continuously monitored in the course of experiments. Total organic carbon (TOC) is chosen and measured as a mineralization index of the ozonation of 2-MT. The results indicate that the decomposition of 2-MT is efficient, while the mineralization of TOC is limited via the ozonation only. Simultaneously, the yield of sulfate with the maximum value of about 47% is characterized by the increases of TOC removal and ozone consumption. These results can provide some useful information for assessing the feasibility of the treatment of 2-MT in the aqueous solution by the ozonation. [Copyright &y& Elsevier]

The dynamic behavior of ozonation with pollutants in a countercurrent bubble column is studied for the model establishment. Bubble columns have been widely used for an ozonation system in the plants and laboratories. In addition, a countercurrent bubble column has been commonly recommended than a cocurrent one because it has a higher ozone transfer efficiency. Therefore, the investigation of this paper focuses on the countercurrent bubble column. As an ozonation process starts, the gas mixture of ozone and oxygen is introduced into the bottom of a column, and then transferred into the liquid. The pollutants in the wastewater are eliminated subsequently via oxidation by the dissolved ozone. There certainly exists a temporary and unsteady period before the ozonation system reaches steady state. However, available ozonation models employed to describe ozone and pollutant profiles have commonly been developed for steady state. The treating qualities of wastewater in the early stage of ozonation are usually not predicted, and the time required for the steady-state establishment remains to be determined. Moreover, oxygen mass transfer is usually neglected in previous ozonation models so that the increase of dissolved oxygen is uncertain. These information is desirable for the proper design and operation of ozonation system in a bubble column. Thus, the aim of this study is to model and investigate the dynamic processes of ozonation with pollutants including oxygen mass transfer. The dynamic axial dispersion model proposed is employed to predict the variation of the ozone, pollutant, and oxygen concentrations profiles. The validity of the model was demonstrated by comparing the predicted results with the experimental data. The o-cresol was chosen as the model pollutant. The temporal concentration variations of the residual o-cresol and dissolved oxygen in the effluent liquid, and the off-gas ozone in the free volume were measured accordingly. Furthermore, the variation of the enhancement factor of ozone and the amount of off-gas were predicted. Note that it usually needs 2–5 hydraulic retention times to approach steady state under the conditions of this study. Further, the effects of dimensionless system parameters on the performance of the ozonation processes are examined. As a result, the proposed dynamic model of ozonation with pollutants is useful for proper prediction of the variables of an ozonation system in a countercurrent bubble column. [Copyright &y& Elsevier]

Studies the decomposition of 2-naphthalenesulfonate in aqueous solution by ozonation with ultraviolet radiation. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on water research.