Combining quantum chemical programs with experiments: a discussion of the photocatalytic reaction of non-ionic surfactant NPnEO

• Main Authors: Lin-Qi You, 游林祺
• Other Authors: 陳孝行
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/79s5p3

碩士 === 國立臺北科技大學 === 環境工程與管理研究所 === 99 === NPnEO is the non-ionic surfactants which were most commonly used in industrial processes. When disseminated in the environment, other NP-products category will be formed by the mechanism of microorganisms. Such substances can not be easily decomposed in the water environment and have the characteristics of environmental hormones. General biological treatment is not very efficient, and it will produce NP too. Therefore, this study used photocatalyst to trigger a photocatalytic reaction on NPnEO, explored the intermediates during the photocatalytic reaction, and discussed the changes in the follow-up mechanism. Finally, by this method, this study expects to develop effective treatment technology of NPnEO in the environment. This study calculated Frontier electron density and point charge by semi-empirical method in quantum chemistry programs (ChemBioOffice2008), and together with the GC-MS analysis, discussed the oxidation and mineralization efficiency of NPnEO. With the combination of the above methods, the reaction mechanism can be explained, and a photocatalytic reaction pathway of NPnEO is proposed. Before the NPnEO photocatalytic reaction(by DP-25 and N/Fe-TiO2), this study used the statistical software(STATISTICA) to take the experiment design(Designed by Central Composite Design). According to CCD experiment design, it was found that the best efficiency parameters were pH3.5, photocatalyst concentration:0.5g/L, rotation speed:300RPM for DP-25 and pH4, photocatalyst concentration:1g/L, rotation speed:450RPM for N/Fe-TiO2. By the above experiment, NPnEO degradation efficiencys were higher than 78%(more than 43% organics were mineralization). After the NPnEO water samples(of different reaction time) were collected, this study constructed the three main reaction pathway of NPnEO in photocatalytic process that combined with GC-MS analysis and quantum chemical programs. It also confirmed that after the 240 minutes photocatalytic reaction, the initial intermediates (NPnEO, NPnEC, etc.) were broken down into low molecular weight substances(2 - (vinyloxy) ethanol, stearic acid and diethoxymethane, etc.), and ultimately achieve the purpose of mineralization.