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Surface Characterization of Mechanochemically Modified Exfoliated Halloysite Nanoscrolls
Langmuir ( IF 3.7 ) Pub Date : 2017-03-28 00:00:00 , DOI: 10.1021/acs.langmuir.6b04606 Balázs Zsirka , Attila Táborosi , Péter Szabó , Róbert K. Szilágyi 1 , Erzsébet Horváth , Tatjána Juzsakova , Dávid Fertig , János Kristóf
Langmuir ( IF 3.7 ) Pub Date : 2017-03-28 00:00:00 , DOI: 10.1021/acs.langmuir.6b04606 Balázs Zsirka , Attila Táborosi , Péter Szabó , Róbert K. Szilágyi 1 , Erzsébet Horváth , Tatjána Juzsakova , Dávid Fertig , János Kristóf
Affiliation
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Surface modifications fundamentally influence the morphology of kaolinite nanostructures as a function of crystallinity and the presence of contaminants. Besides morphology, the catalytic properties of 1:1-type exfoliated aluminosilicates are also influenced by the presence of defect sites that can be generated in a controlled manner by mechanochemical activation. In this work, we investigated exfoliated halloysite nanoparticles with a quasi-homogeneous, scroll-type secondary structure toward developing structural/functional relationships for composition, atomic structure, and morphology. The surface properties of thin-walled nanoscrolls were studied as a function of mechanochemical activation expressed by the duration of dry-grinding. The surface characterizations were carried out using N2, NH3, and CO2 adsorption measurements. The effects of grinding on the nanohalloysite structure were followed using thermoanalytical thermogravimetric/derivative thermogravimetric (TG/DTG) and infrared spectroscopic [Fourier transform infrared/attenuated total reflection (FTIR/ATR)] techniques. Grinding results in partial dehydroxylation with similar changes as those observed for heat treatment above 300 °C. Mechanochemical activation shows a decrease in the dehydroxylation mass loss and the DTG peak temperature, a decrease in the specific surface area and the number of mesopores, an increase in the surface acidity, blue shift of surface hydroxide bands, and a decrease in the intensity of FTIR/ATR bands as a function of the grinding time. The experimental observations were used to guide atomic-scale structural and energetic simulations using realistic molecular cluster models for a nanohalloysite particle. A full potential energy surface description was developed for the mechanochemical activation and/or heating toward nanometahalloysite formation that aids the interpretation of experimental results. The calculated differences upon dehydroxylation show a remarkable agreement with the mass loss values from DTG measurements.
中文翻译：
机械化学改性的脱落的埃洛石纳米滚动体的表面表征
表面改性从根本上影响高岭石纳米结构的形态，取决于结晶度和污染物的存在。除形态外，1：1型片状铝硅酸盐的催化性能还受到缺陷位点的影响，这些位点可以通过机械化学活化以受控方式生成。在这项工作中，我们研究了具有准均质滚动型二级结构的脱落的埃洛石纳米颗粒，从而形成了组成，原子结构和形态的结构/功能关系。研究了薄壁纳米滚动体的表面特性，该函数是机械化学活化作用的函数，用干磨时间表示。使用N 2，NH 3进行表面表征和CO 2吸附测量。使用热分析热重/衍生热重（TG / DTG）和红外光谱[傅里叶变换红外/衰减全反射（FTIR / ATR）]技术跟踪研磨对纳米卤化物结构的影响。研磨导致部分脱羟基，其变化与在300°C以上的热处理中观察到的变化相似。机械化学活化显示出脱羟基质量损失和DTG峰值温度的降低，比表面积和中孔数量的减少，表面酸度的增加，表面氢氧化物带的蓝移以及强度的降低。 FTIR / ATR谱带是磨削时间的函数。实验观察被用于指导纳米尺度的颗粒的现实分子簇模型的原子级结构和高能模拟。开发了完整的势能表面描述，用于机械化学活化和/或加热至纳米偏磁石的形成，这有助于解释实验结果。脱羟基时计算出的差异与DTG测量的质量损失值显示出显着的一致性。
更新日期：2017-03-28
中文翻译：
机械化学改性的脱落的埃洛石纳米滚动体的表面表征
表面改性从根本上影响高岭石纳米结构的形态，取决于结晶度和污染物的存在。除形态外，1：1型片状铝硅酸盐的催化性能还受到缺陷位点的影响，这些位点可以通过机械化学活化以受控方式生成。在这项工作中，我们研究了具有准均质滚动型二级结构的脱落的埃洛石纳米颗粒，从而形成了组成，原子结构和形态的结构/功能关系。研究了薄壁纳米滚动体的表面特性，该函数是机械化学活化作用的函数，用干磨时间表示。使用N 2，NH 3进行表面表征和CO 2吸附测量。使用热分析热重/衍生热重（TG / DTG）和红外光谱[傅里叶变换红外/衰减全反射（FTIR / ATR）]技术跟踪研磨对纳米卤化物结构的影响。研磨导致部分脱羟基，其变化与在300°C以上的热处理中观察到的变化相似。机械化学活化显示出脱羟基质量损失和DTG峰值温度的降低，比表面积和中孔数量的减少，表面酸度的增加，表面氢氧化物带的蓝移以及强度的降低。 FTIR / ATR谱带是磨削时间的函数。实验观察被用于指导纳米尺度的颗粒的现实分子簇模型的原子级结构和高能模拟。开发了完整的势能表面描述，用于机械化学活化和/或加热至纳米偏磁石的形成，这有助于解释实验结果。脱羟基时计算出的差异与DTG测量的质量损失值显示出显着的一致性。
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