| Summary: | 碩士 === 國立中興大學 === 環境工程學系所 === 105 === Ferrocene (Fc) is proposed as a readily available, non-expensive and Fe2+ containing catalyst for activating Sodium persulfate (PSF), Potassium peroxymonosulfate (PMS) and Sodium percarbonate (SPC). In this study, the activation of PSF/PMS/SPC by Fc is evaluated to the oxidation of toxic Acid Red 27 (AR27) as a model reaction. The combination of Fc and the oxidants completely decolorized AR27. Fc-activated PMS was found to be the most effective oxidant for degrading AR27, followed byFc-activated PSF, and Fc-activated SPC shows worst performance.
In different experimental conditions, increase the dosage of Fc and oxidants can accelerate degradation kinetics. However, if excess Fc was added into the solution, it would result in removal of hydroxyl radicals which cause inhibitory effects on Fc-activated SPC. Elevated temperature and decreased solution pH will improve the degradation efficiency and kinetics. When in alkaline conditions, OH- interfere free radical formation which leads to decrease degradation efficiency. The activation energy of Fc-activated PSF/PMS/SPC was found to be 62.9/12.9/70.4 kJ/mol respectively. When NaCl was added to AR27 solution, Cl- will both scavenge hydroxyl and sulfate radicals.When Cetyltrimethylammonium bromide (CTAB) was ionized to long alkyl chain and bromide ion in AR27 solution, the degradation kinetics became relatively fast compared with the degradation curve in the absence of CTAB for Fc-activated PSF/PMS. In contrast, bromide ion accelerates the decomposition of hydrogen peroxide into water and oxygen for Fc-activated SPC, which cause the decreasing of oxidation capacity. The presence of Sodium dodecyl sulfate (SDS) might interfere with the contact between anionic hydroxyl, sulfate radicals, AR27 and Fc, thereby decreasing the degradation efficiency. Through investigating effects of radical scavengers, the mechanism of AR27 degradation was primarily attributed to hydroxyl and sulfate radicals for Fc-activated PSF/PMS, and hydroxyl radicals for Fc-activated SPC. Fc was also reusable and remained highly effective for activating PSF/PMS/SPC to degrade AR27 even without regeneration treatments. Fc remained intact after the activation according to X-ray diffraction, FT-IR and X-ray photoelectron spectroscopy analyses. These features make Fc an effective and readily-available heterogeneous catalyst.
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