Extraordinary Destabilization of Silica Nanocolloids by Filtration
Extraordinary Destabilization of Silica Nanocolloids by Filtration
复制标题
通过过滤对二氧化硅纳米胶体进行非凡的去稳定化
DOI：
10.1021/acs.langmuir.3c00346
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发表时间：
2023
期刊：
影响因子：
3.9
通讯作者：
Y. Mori
中科院分区：
文献类型：
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作者：
K. Higashitani;Y. Mori
在溶液中的二氧化硅纳米颗粒通过具有比颗粒直径Dp大得多的孔径的注射器过滤器过滤之后，通过使用两种不同尺寸的颗粒来研究过滤对在1 M KCl溶液中的快速凝固速率、动态光散射直径和pH = 1.6的zeta电位的影响：二氧化硅和胶乳的S颗粒（Dp ≤ 50 nm）和二氧化硅的L颗粒（Dp ≤ 300 nm）。结果表明，过滤可使二氧化硅粒子的流体动力学直径变小，zeta电位的绝对值显著降低，但对胶乳粒子则不然。对于快速凝固速率，通过过滤，二氧化硅S颗粒的值增加了2个数量级以上，但在二氧化硅L和胶乳S颗粒的情况下没有发现显著差异。根据这些数据，推测通过过滤从二氧化硅S颗粒的表面除去凝胶状层，并且凝胶状层的存在导致快速凝固速率降低约2个数量级。通过修正的Smoluchowski理论，我们成功地估计了Dp < 150 nm时二氧化硅颗粒快速凝聚的显著减少，我们称之为Higashitani-Mori（HM）模型。当Dp < ca时，滤后颗粒的快速凝聚速率随粒径的减小而缓慢下降。250 nm，这也是正确的HM模型估计，忽略了凝结颗粒的再分散的贡献。本研究的另一个发现是，即使通过过滤去除凝胶样层，凝胶样层也会随着时间的推移而恢复，尽管目前尚不清楚这种恢复的详细机制，并将其作为未来的问题。
After silica nanoparticles in solutions were filtered by a syringe filter with a much larger pore size than the particle diameterDp, the filtrated effects on the rapid coagulation rate in 1 M KCl solution, the dynamic light scattering diameter, and the zeta potential at pH ∼ 6 were investigated by employing the particles of two different sizes: S particles (Dp∼ 50 nm) of silica and latex and L particles (Dp∼ 300 nm) of silica. It was found that the hydrodynamic diameters of silica particles became a little smaller and the absolute values of their zeta potentials decreased significantly by filtration, but that is not the case for latex particles. As for the rapid coagulation rate, the value of silica S particles increased more than 2 orders of magnitude by filtration, but no significant difference was found in the case of silica L and latex S particles. From these data, it was postulated that the gel-like layer was removed from the surface of silica S particles by filtration and the existence of the gel-like layer resulted into about 2 orders of magnitude reduction of the rapid coagulation rate. The extraordinary reduction of rapid coagulation of silica particles atDp< 150 nm was successfully estimated by the revised Smoluchowski theory, which we call the Higashitani–Mori (HM) model. It was also found that the rapid coagulation rate of filtrated particles decreased slowly with a decreasing particle size atDp< ca. 250 nm, which was also estimated properly by the HM model, neglecting the contribution of the redispersion of coagulated particles. Another finding in this study was that the gel-like layers were recovered with time even if they were removed by filtration, although the detailed mechanism of this recovering is not known at present and left as a future problem.