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Metabentonite and metakaolin-based geopolymers/zeolites: relation between kind of clay, calcination temperature and concentration of alkaline activator
Journal of Thermal Analysis and Calorimetry ( IF 3.0 ) Pub Date : 2023-05-27 , DOI: 10.1007/s10973-023-12267-1
Michal Slaný , Eva Kuzielová , Matúš Žemlička , Marián Matejdes , Alena Struhárová , Martin T. Palou

In this paper, the composition and properties of two different activated calcinated clays were investigated under selected curing conditions. The tendency of metabentonite and metakaoline to form geopolymers and zeolites was investigated by FTIR spectroscopy, TGA and DSC techniques, PXRD, HT-PXRD, SEM, and BET-N2 adsorption analyses. The selection of the optimal sample compositions was done on a basis of preliminary results obtained from bentonite and kaolin clays activated at calcination temperatures (700, 750, 800 °C) with a holding time of 3 h in a combination with different NaOH concentrations (5, 10, 20 mass%). In a more detailed examination, the samples calcined at a temperature of 800 °C with different NaOH concentrations were studied. For metakaolin-based samples, dominant geopolymer formation was achieved using 5 mass% NaOH. The zeolite amount increased concomitantly with the concentration of the alkali activator, whereas zeolite A and zeolite P were determined as the predominant phases. For metabentonite-based samples, 10 mass% NaOH concentration was found to be optimal by the means of geopolymer formation. At higher alkaline activator concentrations, the presence of zeolitic phases faujasite and gobbinsite was confirmed. However, the determined degree of crystallinity was significantly lower than in the corresponding activated metakaolin samples. With a gradual increase in NaOH concentration, the specific surface area of the metabentonite-based samples increased reaching a value of 218.95 m2 g−1 promising for adsorption applications. The opposite effect was observed for the metakaolin-based samples, and this result is caused by the increased formation of zeolite phases and corresponding changes in their channel dimensions.



中文翻译:

偏膨润土和偏高岭土基地质聚合物/沸石:粘土种类、煅烧温度和碱性活化剂浓度之间的关系

在本文中,研究了两种不同活性煅烧粘土在选定固化条件下的组成和性能。通过 FTIR 光谱、TGA 和 DSC 技术、PXRD、HT-PXRD、SEM 和 BET-N 2研究了偏膨润土和偏高岭土形成地质聚合物和沸石的趋势吸附分析。最佳样品组成的选择是根据在煅烧温度(700、750、800°C)下活化的膨润土和高岭土获得的初步结果进行的,保持时间为 3 小时,结合不同的 NaOH 浓度(5 , 10, 20 质量%)。在更详细的检查中,研究了在 800 °C 的温度下用不同的 NaOH 浓度煅烧的样品。对于基于偏高岭土的样品,主要的地质聚合物形成是使用 5 质量%的 NaOH 实现的。沸石量随着碱性活化剂的浓度而增加,而沸石 A 和沸石 P 被确定为主要相。对于基于偏膨润土的样品,通过地质聚合物的形成,发现 10 质量%的 NaOH 浓度是最佳的。在较高的碱性活化剂浓度下,证实了沸石相八面沸石和戈宾石的存在。然而,测定的结晶度明显低于相应的活化偏高岭土样品。随着 NaOH 浓度的逐渐增加,变膨润土基样品的比表面积增加,达到 218.95 m2  g -1有望用于吸附应用。对于基于偏高岭土的样品观察到相反的效果,该结果是由沸石相的形成增加及其通道尺寸的相应变化引起的。

更新日期:2023-05-27
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