Laboratory of Environmental and Medical Geology, IMAA-CNR, Tito Scalo (PZ), Italy.
Waste Manag. 2010 May;30(5):839-47. doi: 10.1016/j.wasman.2009.11.015. Epub 2010 Jan 19.
In this study Italian coal fly ash was converted into several types of zeolite in laboratory experiments with temperatures of crystallization ranging from 35 up to 90 degrees C. Distilled and seawater were used during the hydrothermal synthesis process in separate experiments, after a pre-treatment fusion with NaOH. The results indicate that zeolites could be formed from different kind of Italian coal fly ash at low temperature of crystallization using both distilled and seawater. SEM data and the powder patterns of X-ray diffraction analysis show that faujasite, zeolite ZK-5 and sodalite were synthesized when using both distilled and seawater; zeolite A crystallized only using distilled water. In particular the experiments indicate that the synthesis of zeolite X and zeolite ZK-5 takes place at lower temperatures when using seawater (35 and 45 degrees C, respectively). The formation of sodalite is always competitive with zeolite X which shows a metastable behaviour at higher temperatures (70-90 degrees C). The chemical composition of the fly ash source could be responsible of the differences on the starting time of synthesized zeolite with distilled water, in any case our data show that the formation of specific zeolites takes place always at lower temperatures when using seawater.
在这项研究中，意大利煤灰在实验室实验中被转化为几种沸石，结晶温度范围从 35 摄氏度到 90 摄氏度。在分别使用蒸馏水和海水的水热合成过程中，在与 NaOH 进行预处理融合后使用。结果表明，使用蒸馏水和海水可以在低温下从不同类型的意大利煤灰中形成沸石。SEM 数据和 X 射线衍射分析的粉末图谱表明，当使用蒸馏水和海水时，合成了方沸石、沸石 ZK-5 和钠沸石；沸石 A 仅使用蒸馏水结晶。特别是，实验表明，当使用海水时，沸石 X 和沸石 ZK-5 的合成温度较低（分别为 35 和 45 摄氏度）。钠沸石的形成总是与沸石 X 竞争，沸石 X 在较高温度（70-90 摄氏度）下表现出亚稳行为。煤灰来源的化学成分可能是导致使用蒸馏水时合成沸石开始时间不同的原因，但无论如何，我们的数据表明，使用海水时，形成特定沸石的温度总是较低。
