Belviso Claudia, Peddis Davide, Varvaro Gaspare, Abdolrahimi Maryam, Reverberi Andrea Pietro, Cavalcante Francesco
Istituto di Metodologie per l'Analisi Ambientale-CNR, 85050 Tito Scalo, Italy.
Departments of Chemistry and Industrial Chemistry (DCIC), Università of Genova, 16146 Genova, Italy.
Materials (Basel). 2020 Oct 16;13(20):4633. doi: 10.3390/ma13204633.
A sample of rhyolitic obsidian (OS) was used as raw material for zeolite synthesis by long (4 days) and fast (2 h)-aging hydrothermal processes. Zeolite synthesis was also performed by a fast (2 h) sonication method. The products were analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) both immediately after and 3 years after their formation in order to determine the stability of synthetic materials according to the method used. The results confirm zeolitization of obsidian both by long-aging conventional hydrothermal heating and fast hydrothermal process. However, the data highlight the efficiency of direct ultrasound energy in achieving more stable zeolite crystals over time. These results carried out using a natural source, follow those already obtained using wastes and pure sources as raw materials thus providing a definitive validation of the different mechanisms controlling zeolite formation according to the process used. Moreover, the results confirm the effectiveness of ultrasonic energy in the formation of zeolites that are more stable over time. Due to the chemical composition of the obsidian precursor, all synthetic zeolites show good magnetic properties (i.e., saturation magnetization), in view to potential magnetic separation.
采用流纹岩黑曜岩（OS）样品作为原料，通过长时间（4天）和快速（2小时）老化水热法合成沸石。还通过快速（2小时）超声法进行沸石合成。在产物形成后立即以及形成3年后，通过X射线衍射（XRD）和扫描电子显微镜（SEM）对产物进行分析，以便根据所用方法确定合成材料的稳定性。结果证实，通过长时间老化的传统水热加热和快速水热法都可使黑曜岩发生沸石化。然而，数据突出了直接超声能量随着时间推移形成更稳定沸石晶体的效率。使用天然原料得到的这些结果，与之前使用废料和纯原料作为原料所获得的结果一致，从而为根据所用工艺控制沸石形成的不同机制提供了明确验证。此外，结果证实了超声能量在形成随时间推移更稳定的沸石方面的有效性。鉴于潜在的磁分离，由于黑曜岩前驱体的化学成分，所有合成沸石都表现出良好的磁性（即饱和磁化强度）。
