| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 100 === This study investigated the feasibility of synthesizing mesoporous molecular sieve, MCM-41, by alkali fusion and hydrothermal processes, using water purification sludge ash (WPSA) and waste glass (WG) as starting Si and Al sources. Aluminum from the WPSA was incorporated into the resultant Al-MCM41, which contributed to the strength and the hydrothermal stability of the MCM-41 structure, and also enhanced the adsorption of organic dye (i.e., methyl blue), as compared to MCM-41 synthesized from pure sodium metasilicate. The proper conditions for the mix ratio of WPSA and WG, alkali fusion/extraction for the preparation of precursor solution, and the hydrothermal process were studied, the resultant Al-MCM-41s were characterized. The residues from the alkali fusion/extraction process were also converted into zeolite (Cancrinite) for a total retrieval.
The results indicated WPSA containing Quartz and Illite, was less extractable for Si as compared to the WG, containing amorphous silicates. Accordingly, the increase in WG portion of the starting mixture increased the extracted quantity of Si. It is noted that the proper mix ratio is about 1:1 that may be expected to generate a precursor solution with a suitable range of Si/Al for the synthesis of Al-MCM-41. All the starting materials were tested with TCLP and showed they are safe below the regulatory thresholds. The Al-MCM-41 hydrothermally synthesized with 1:1 mix ratio of the starting materials show that the surface area (860 m2/g), pore diameter (3.16 nm), pore volume (0.85 cm3/g), d100 (3.73 nm), a0(4.31 nm) and wall thickness(1.15 nm) are close to that of pure MCM-41. However, the hydrothermal stability and adsorption of organic dye (methyl blue) outperform that of the pure MCM-41. Furthermore, the impurity such as Na2O, K2O, and Fe2O3, derived from the starting wastes are less or close to 1%, and have no significant effects on the on the synthesis and performance of the Al-MCM-41. In addition, the residues resulted from the alkali fusion/extraction was successfully synthesized into zeolites (Cancrinite and the other unnamed) for a secondary retrieval/recycling purpose, suggesting a total retrieval/recycling of the water purification sludge and waste glass.
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