Photodegradation of Phenol in Aqueous Solution with UV/TiO2

• Main Authors: Hsing-Jane Liao, 廖倖娟
• Other Authors: Yi-Chang Lin
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/03739674091822513144

碩士 === 國立臺灣大學 === 環境衛生研究所 === 89 === Researchers have recently studied photodegradation of organic contamination using UV/TiO2, including heterogeneous photocatalysis using low energy UV light and semiconductor. This technology mineralizes the contamination into harmless compounds, such as H2O and CO2, with more efficient manner than conventional treatments do. We developed a model system for the photodegradation of phenol in aqueous solution using small diameter (d=0.0041m) U-shaped lamps coated with TiO2 (weight 0.14135 g) on surface of lamps. The reaction chamber for the present experiment included seven U-shaped lamps. The present study investigated variables that influenced the photodegradation in batch experiments, including the initial concentration of phenol, pH, partial pressure of O2 in the gas bubbled, and the temperature of reaction. The results of adsorption and evaporation experiments showed that the concentration of phenol decreased to a limited level as the reaction time increased. Based on an aeration model at the rates of 0, 110, 290, 390 cc/min, the results showed that the phenol conversion rate reached 98.7% at the rate of 290 cc/min, with a minimum remnant (77.34% removed) of hydroquinone, the intermediate product. There was no obvious additional gain in the conversion rate when the aeration was increased to 390 cc/min. The chemical conversion reached the highest level when the pH was 5, demonstrating the fastest reaction rate and a minimum remnant of hydroquinone. However, the photodegradation efficiency decreased as the pH level in the solution increased. For phenol solution with the pH level of 11, 11.2% of phenol remained after a 240-minute irradiation. Our results also showed that this system had the best reaction rate, and the highest surface coverage (θ=98.84%) when the initial concentration of phenol was 280 mg/L. With this amount of phenol, we inferred that the system was at the utmost limit of photodegradation. As regards the effect of temperature, we found that photodegradation was at the best efficiency at 40℃. The efficiency decreased as the temperature was lower or higher than this level. In conclusion, the optimum condition of this UV/TiO2 model for degrading phenol were when the aeration rate was 290 cc/min, pH level was 5, and the reaction temperature was 40℃. With initial phenol concentration of 280 mg/L, the catalyst reactant in this reactor had the adsorption capacity reached the utmost limit.