| Summary: | 碩士 === 明志科技大學 === 生化工程研究所 === 99 === This research is about methylene blue (MB) removal mechanism with manganese oxide at different oxygen concentrations (opened-container, nitrogen aeration, oxygen aeration) and pH values. Use inductively coupled plasma (ICP) to analysis dissolved manganese ion, and UV/Vis spectrometer all-wavelength analysis, high performance liquid chromatography-mass spectrometer (HPLC-MS) to analysis the reactive intermediates and final products qualitatively. Then, study the roles of adsorption mechanism and manganese oxide with data results.
As a result, the ICP data showed that pH4 had the highest dissolved manganese ion concentration, and the UV/Vis all-wavelength scan result indicated that after manganese oxide react with methylene blue, there was a blue-shift appears at the acidic environment, which was determined as thionin (Th). Furthermore, manganese oxide is the major oxidant at pH4 in all three different oxygen concentrations. However, compare the different oxygen concentrations with all-wavelength analysis in the nitrogen aeration of pH6 system, the adsorption peak increases with time, which was speculated that the initial state of manganese oxide was adsorbed and processed oxidation in the final state.
Under the alkaline condition, dissolved manganese ion concentration decreases after the reaction, and unable to find efficient color removal with the all-wavelength analysis. Particularly, the methylene blue specific absorbing peak is 665nm and had noticeable decrease trends at pH8 and pH10. In the meantime, the HPLC-MS analysis results showed that there is only one single reactive intermediate, thionin(228) in the environment of pH6 and pH 8 after manganese oxide react with methylene blue. However, there were many reactive intermediates, such as azure A, azure C and the final dye thionin in pH4 and pH6 environments that proved the electron transfer phenomenon between dye molecules and manganese oxide.
In summary, the main reaction mechanics of methylene blue are: (1) adsorption and the fall off stage of auxochrome, (2) further degradations of reactive intermediates.
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