| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 92 === The objective of this study was to investigate the ozone dissolution in a bubble column and packed bed reactor, and probe into the effect of mass transfer for the surface of aluminosilicate coated with TiO2, dosage of the t-butanol, temperature and mangan(Ⅱ)-sulfate-monohydrate. Decomposition of o-cresol in aqueous solution by the TiO2/O3, TBA/O3 and MnO2/O3 processes has been studied under various operation factors such as pH value, temperature, concentration of ozone in the gas phase and the amounts of metallic oxide.
Packed bed reactor exhibited better removal efficiency of o-cresol than bubble reactor at pH 3.0, but both that were almost the same for the removal rate of o-cresol at pH 11.0. Reactivity of o-cresol is insignificant affected by temperature, and the amounts of ozone consumption increased with increasing the solubility of ozone, so the removal rate of o-cresol is very fast under the lower temperature.
Amounts of titanium dioxide coated on aluminosilicate insignificantly affected the degradation of o-cresol, and mineralization increased with increasing amounts of TiO2. Moreover, the removal efficiency of o-cresol is the best when the amount of suspended TiO2 is 7.6mg/L. The ozonation of o-cresol increased with increasing pH value, but in the alkalinitie solution, the surface of titanium dioxide contains more negative charge, so it is difficult for negatively charged by-products to adsorb on TiO2 surface, which resulted in lower mineralization.
At lower pH, the t-butanol provides increased gas-liquid contact area of mass transfer and results indicate the rate constant with addition of t-butanol was about 2.5 times than that without t-butanol.
The dissolution rate of manganese dioxide was strongly pH dependent and decreased with increasing pH value. The dissolution time of maximum manganese ion reduced with increasing concentration of ozone. It’s clear that in the presence of MnO2 there is lower residual ozone in comparison to the case of pure water, indicating that MnO2 has the ability to enhance the utilization of ozone. Few amounts of manganese dioxide insignificantly affected the decomposition of o-cresol, so an optimal amount of manganese dioxide will be enhanced the degradation and mineralization. Decomposition of o-cresol reduced with increasing the concentration of mangan(Ⅱ)-sulfate-monohydrate, but mineralization is poor in high concentration.
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