Abstract

The study of the properties and composition of natural nanoparticles is an essential problem in analytical chemistry. Currently, there are no reference samples of natural nanoparticles, which complicates the study of the role of nanoparticles in specific processes, including geochemical ones, and makes it almost impossible to compare the results obtained by different researchers. In this work, nanoparticles of kaolinite, montmorillonite, and muscovite are studied as potential reference samples of natural nanoparticles. A complex of analytical methods has been proposed for the isolation and characterization of mineral nanoparticles, including the field flow fractionation of particles in a rotating coiled column, laser diffraction, scanning electron microscopy, and inductively coupled plasma atomic emission spectrometry. According to laser diffraction data, 93–98% of the isolated particles are from 40 to 300 nm in size; 2–7% of particles have sizes of up to 830 nm. The sizes of the isolated particles were confirmed by scanning electron microscopy. Based on the aluminum content, the concentrations of mineral nanoparticles in the isolated suspensions were estimated. The aggregation stability of nanoparticles in 5 mM phosphate buffer solutions of pH 6, 7, and 8 was studied. Muscovite nanoparticles are stable at pH 7 and 8 for at least 4 weeks, while montmorillonite nanoparticles have similar stability only at pH 8. For kaolinite nanoparticles, significant aggregation was observed at all studied pH values of buffer solutions. The obtained experimental results made it possible to clarify the problems and assess the prospects for developing reference samples of natural nanoparticles.

中文翻译：

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天然纳米颗粒参比样品开发中旋转盘管中的场流分馏

摘要

研究天然纳米粒子的性质和组成是分析化学中的一个基本问题。目前，没有天然纳米粒子的参考样本，这使得纳米粒子在包括地球化学在内的特定过程中的作用的研究变得复杂，并且几乎不可能比较不同研究人员获得的结果。在这项工作中，高岭石、蒙脱石和白云母的纳米颗粒被研究作为天然纳米颗粒的潜在参考样品。已经提出了一系列用于矿物纳米粒子的分离和表征的分析方法，包括旋转螺旋柱中粒子的场流分馏、激光衍射、扫描电子显微镜和电感耦合等离子体原子发射光谱法。根据激光衍射数据，93-98% 的分离颗粒尺寸在 40-300 nm 之间；2–7% 的颗粒尺寸高达 830 nm。通过扫描电子显微镜确认分离颗粒的尺寸。根据铝含量，估计分离的悬浮液中矿物纳米颗粒的浓度。研究了纳米颗粒在 pH 6、7 和 8 的 5 mM 磷酸盐缓冲溶液中的聚集稳定性。白云母纳米颗粒在 pH 7 和 8 下稳定至少 4 周，而蒙脱石纳米颗粒仅在 pH 8 下具有相似的稳定性。对于高岭石纳米颗粒，在所有研究的缓冲溶液 pH 值下观察到显着聚集。