鎂鋁氧化物及類水滑石對氯離子吸附行為之研究

簡志峰(Chih-feng Chien)

指導教授 ： 李釗

國立中央大學/工學院/土木工程學系/碩士(2013年)

摘要

氯離子的存在會嚴重影響結構物的品質及耐久性，特別是鋼筋混凝土，如何降低或控制氯離子含量，降低氯離子對結構物的影響一直是許多人努力的目標。
水滑石(Hydrotalcite, 簡稱HT )為現有已知具有離子吸附能力的一種陰離子黏土，由帶正電的金屬層版及層間陰離子所組成，常見的水滑石組成為鎂鋁-碳酸根水滑石，不同的金屬層版或層間陰離子，但具有類似結構者稱類水滑石( Hydrotalcite-like compound, LDHs )，可藉由人工製造或天然提煉，亦是爐石(slag)水化過程中的水化產物之一。其吸附原理是藉由金屬層板所帶正電吸引陰離子結合成穩定的化合物，高溫處理為其中一種使水滑石恢復離子吸附能力的方式，而高溫後的產物稱為鎂鋁氧化物( MgAlO4 )。
本研究分別探討市售水滑石經鍛燒後形成之「鎂鋁氧化物」，以及藉鹼活化爐石粉產生類水滑石產物後，對氯離子的吸附行為。結果顯示鎂鋁氧化物對於氯離子、氫氧根離子皆具有一定的吸附能力。鎂鋁氧化物的使用於水泥漿體中，氯離子吸附量隨鎂鋁氧化物使用量增加而增加。鹼活化爐石漿體部分，氯離子吸附量隨試體養護齡期增加，而增加使用氫氧化鈉作為鹼活化劑，矽酸鎂為鎂添加劑，鎂/鋁莫耳比5.0時游離氯溶出量較小，而碳酸鎂為鎂添加劑，鎂/鋁莫耳比5.0時固定氯溶量較高，由XRD觀察可發現使用氫氧化鈉的配比，類水滑石生成情形較為明顯。

關鍵字

水滑石 ； 鎂鋁氧化物 ； 游離氯 ； 固定氯

並列摘要

Hydrotalcite ( HT) is known to have an existing ion adsorption capacity of an anionic clay, Hydrotalcite is composed of cation layer and the interlayer anions, commonly composed of Mg-Al hydrotalcite - carbonate hydrotalcite, can be extracted by artificial or natural, is also the hydration process of hydration products of slag. The adsorption principle is brought by cation attract positively charged anion binding a stable compound. One of the high-temperature treatment to restore the ion adsorption capacity hydrotalcite way, the product called magnesium aluminum oxide (MgAlO4) .
This study investigate the commercial calcined hydrotalcite formed by the Mg-Al oxides, and produced by alkali-activated slag product Hydrotalcite after the chloride ion adsorption behavior.
The results showed that the Mg-Al oxides have certain adsorption capacity to chloride and hydroxide. Mg-Al oxides used in the cement paste, the adsorption of chloride will increases by Mg-Al oxides usage increases. In Alkali activated slag paste, the chloride ion adsorption increased with increasing specimen curing period and use of sodium hydroxide as alkali activator, magnesium silicate additives of magnesium, magnesium / aluminum molar ratio of 5.0, the less of free chloride, and magnesium carbonate magnesium additive, magnesium / aluminum molar ratio of 5.0, amount of unmovable chloride dissolved higher .XRD observation can be found using the ratio of sodium hydroxide, hydrotalcite generate situations are obvious.

並列關鍵字

Hydrotalcite ； Mg-Al oxides, ； free chloride ； unmovable chloride

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