National Institute for Research and Development of Optoelectronics Bucharest INOE 2000, Research Institute for Analytical Instrumentation, 67 Donath Street, 400293 Cluj-Napoca, Romania.
SC UTCHIM SRL, 12 Buda Street, 240127 Ramnicu Valcea, Romania.
Molecules. 2020 May 31;25(11):2570. doi: 10.3390/molecules25112570.
This study presents the effect of thermal treatment (450, 500, 600, 750, and 800 °C) on a Romanian clinoptilolite-rich natural zeolite, along with the interaction of raw and thermally treated zeolites with simulated gastric fluid (SGF, pH = 1.20) at different zeolite to SGF ratios and exposure times. The zeolites were characterized using gravimetric analysis, X-ray fluorescence, powder X-ray diffraction (pXRD), and Fourier transform infrared (FT-IR) spectroscopy. The chemical composition of the zeolite subjected to thermal treatment did not change significantly with the increase of temperature. Structural changes were not detectable by pXRD and FT-IR analyses in the zeolites thermally treated up to 500 °C, while above 600 °C a gradual structural breakdown of zeolite was noticed. At high temperatures, the broad, low-intensity peaks in pXRD patterns indicated the partial amorphization of the crystalline structure. The pXRD and FT-IR analyses showed that the crystalline structure of zeolites remains unaffected after their exposure to SGF. The results revealed that the amounts of Fe, Na, Mg, K, Ca, Al, and Si released depends mainly on the zeolite to SGF ratio, and to a lower extent on the thermal treatment temperature, while the exposure time of 1 to 7 days does not have a significant impact on the elements released in SGF.
本研究探讨了热处理（450、500、600、750 和 800°C）对罗马尼亚富含斜发沸石的天然沸石的影响，以及天然沸石和热处理沸石与模拟胃液（SGF，pH=1.20）在不同沸石与 SGF 比例和暴露时间下的相互作用。采用重量分析、X 射线荧光、粉末 X 射线衍射（pXRD）和傅里叶变换红外（FT-IR）光谱对沸石进行了表征。热处理沸石的化学组成随温度升高变化不大。在 500°C 以下的热处理沸石中，pXRD 和 FT-IR 分析未检测到结构变化，而在 600°C 以上，沸石的结构逐渐破坏。在高温下，pXRD 图谱中宽而弱的峰表明晶体结构的部分非晶化。pXRD 和 FT-IR 分析表明，沸石在暴露于 SGF 后其晶体结构保持不变。结果表明，释放的 Fe、Na、Mg、K、Ca、Al 和 Si 量主要取决于沸石与 SGF 的比例，而在较小程度上取决于热处理温度，而 1 至 7 天的暴露时间对 SGF 中释放的元素没有显著影响。
