Optical Fiber and Photoelectrochemical Reactor for the Decomposition of Gaseous Isopropanol in Air Stream by UV/TiO2 Process

• Main Authors: Wei-Ming Hou, 侯韋銘
• Other Authors: Young Ku
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/52209459070634581159

博士 === 國立臺灣科技大學 === 化學工程系 === 101 === Photocatalytic decomposition of isopropanol presented in gas stream was investigated using a continuous, tubular photoreactor loaded with single TiO2-coated optical fiber under controlled UV periodic illumination. The effects of UV light intensity, initial concentration of target compound, retention time and humidity on the photocatalytic efficiency for the oxidation of isopropanol. The TiO2 particles were coated on optical fiber through dip-coating process. UV light emitting diodes (UV-LEDs) will be utilized as the light source to enhance the utilization of UV light by applying periodic illumination on the oxidation of isopropanol. The introduction of humidity retarded the decomposition of isopropanol because of the competition between water and isopropanol molecules for the active sites on TiO2 surface. Operated at retention time of less than one second, about 21% isopropanol was decomposed for experiments conducted with initial isopropanol concentration of 10 ppmv. The apparent quantum yield was increased from 0.78 to 1.28 for experiments conducted with UV-LED as the light source operated at duty cycle shifted from 1.0 to 0.1. At the operation of equivalent duty cycle, both removal efficiencies and quantum yield was also enhanced in the highly frequent periodic illumination by decreasing both light and dark periods. Electrochemical enhancement for photocatalytic decomposition of isopropanol in gas phase was carried out in a photoelectrocatalytic reactor. The effects of bias potential, relative humidity, initial isopropanol concentration and UV light intensities were investigated for the photoelectrocatalytic process. Photoelectrocatalytic decomposition of isopropanol was observed to be less sensitive to humidity for experiments applied with bias potential higher than 2.5V. Electrical current densities of photoanode were highly corresponded to the variation of bias potentials, relative humidity levels and UV light intensities, however independent of inlet isopropanol concentrations. Humidity presented a controversial effect for photocatalytic decomposition rate of isopropanol within the application of bias potential. Experimental results also exhibited that the energy consumption of photoelectrocatalytic process was much less than photocatalytic process to achieve similar isopropanol decomposition.