利用淨水污泥灰與廢玻璃水熱合成鋁矽質中孔徑MCM-41之特性研究

Hydrothermal synthesis of aluminosilicate mesoporous MCM-41 from water purification sludge ash and waste glass

盧柏雅(Po-ya Lu)

指導教授 ： 王鯤生

國立中央大學/工學院/環境工程研究所/碩士(2012年)

摘要

本研究利用淨水污泥灰與廢玻璃當中之矽、鋁源作為合成中孔徑Al-MCM-41之材料，首先將淨水污泥灰及廢玻璃混合後，以鹼熔法萃取矽、鋁元素，並使用三種不同液固比(L/S=3、7、15)之前趨液合成材料，並探討不同矽鋁比對於Al-MCM-41結構的物化特性影響，且與偏矽酸鈉合成之MCM-41作比較，最後萃取SiO2後之剩餘灰渣合成微孔沸石吸附劑，以達到全資源化之效果。而研究結果方面，首先將淨水污泥灰與廢玻璃以1：1之比例混合，此時所得到之矽鋁比範圍為10至30間，其值對於後續實驗將不會有過低造成合成不易及過高影響應用性的問題發生。之後再將混合後原物料利用鹼熔進行最大SiO2萃取試驗，以得到最大再利用率，而鹼熔最佳條件為氫氧化鈉比混合灰為1.5 、鹼熔溫度為550 ℃之配比下，可將石英相(Quartz,SiO2)完全轉換成矽酸鹽類及矽鋁酸鹽類，且SiO2最大萃取量為427 mg/g，之後將鹼熔後產物加入三種不同液固比之去離子水，以得到前趨液進行合成，而前趨液中元素主要為Si、Al、Fe及Na，其中又以鋁元素對合成後MCM-41結構所造成的影響最大，而當液固比為3時，矽鋁比為13.5最低，而在液固比為15時，矽鋁比為32.6最高。將三種不同矽鋁比之前趨液以不同的水熱溫度進行合成的試驗中，以105 ℃所合成MCM-41材料XRD繞射峰皆為最強，結構也最為完整。而該合成溫度下的材料結構特性方面，以液固比為15，前趨液矽鋁比為32.6時，其比表面積為860 m2/g、孔體積為1.04 cm3/g、孔壁厚度1.15 nm為最高，而隨液固比及前趨液矽鋁比降低，比表面積、孔體積及孔壁厚度則下降，顯示高矽鋁比可得到性質較優良之分子篩材料。由27Al NMR圖譜可發現在54 ppm時皆有波峰產生，表示鋁原子為鋁氧四面體，證實鋁原子有進入到MCM-41骨架中。在水熱穩定度試驗中，以較高矽鋁比材料，表現出良好的水熱穩定性。亞甲基藍去除率試驗中，在初始濃度為0.28 mmole/L及接觸達平衡時，以矽鋁比最低之Al-MCM-41其吸附量為0.270 mmole/g；去除效率為96.5 %最大。最後剩餘灰渣，在水熱反應溫度為200 ℃時，可合成出鈣霞石(Cancrinite)微孔沸石，證實具有二次回收之潛力。

關鍵字

鈣霞石 ； 水熱穩定性 ； MCM-41 ； 淨水污泥灰 ； 廢玻璃

並列摘要

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.

並列關鍵字

Cancrinite ； Hydrothermal stability ； Water Purification Sludge ash ； MCM-41 ； Waste glass

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