1
|
Higashitani K, Mori Y. Extraordinary Destabilization of Silica Nanocolloids by Filtration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5554-5560. [PMID: 37027321 DOI: 10.1021/acs.langmuir.3c00346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
After silica nanoparticles in solutions were filtered by a syringe filter with a much larger pore size than the particle diameter Dp, 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 at Dp < 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 at Dp < 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.
Collapse
Affiliation(s)
- Ko Higashitani
- Department of Chemical Engineering, Kyoto University─Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yasushige Mori
- Department of Chemical Engineering and Materials Science, Doshisha University, Tatara Miyakodani 1-3, Kyotanabe 610-0321, Japan
| |
Collapse
|
2
|
Sun H, Jiao R, An G, Xu H, Wang D. Influence of particle size on the aggregation behavior of nanoparticles: Role of structural hydration layer. J Environ Sci (China) 2021; 103:33-42. [PMID: 33743914 DOI: 10.1016/j.jes.2020.10.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/10/2020] [Accepted: 10/11/2020] [Indexed: 06/12/2023]
Abstract
More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130-480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and pH all affected fast aggregation rate coefficients of 130 nm nanoparticles. Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.
Collapse
Affiliation(s)
- Hongyan Sun
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruyuan Jiao
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Guangyu An
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Hui Xu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Dongsheng Wang
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| |
Collapse
|
3
|
Higashitani K, Nakamura K, Fukasawa T, Tsuchiya K, Mori Y. Ionic Specificity in Rapid Coagulation of Silica Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2505-2510. [PMID: 29360379 DOI: 10.1021/acs.langmuir.7b04081] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The Smoluchowski theory has been widely accepted as the basic theory to estimate the rapid coagulation rate of colloidal particles in electrolyte solutions. However, because the size and specificity of molecules and ions are not taken into account, the theory is applicable only if the particle size is large enough to neglect the effects caused by the structured layers composed of water molecules, ions, and hydrated ions adsorbed on the colloidal surface. In the present study, the rapid coagulation rates of silica nanoparticles in concentrated chloride and potassium solutions were measured by using a low-angle light-scattering apparatus, and the dependence of the experimental value of rapid coagulation rate, KER, on the particle diameter, Dp, and also on the Gibbs free energy of hydration of ions, ΔGhyd, was investigated extensively. The following were found. (1) When the particle size was small enough, the value of KER reduced exponentially not only with the decreasing particle size but also with the increasing value of (-ΔGhyd) of cations (counterions) in the case of chloride solutions and with that of anions (coions) in the case of potassium solutions. (2) Silica nanoparticles of Dp ≲ 70 nm in 1 M KNO3 and KSCN solutions did not coagulate at all, although they coagulated at Dp ≳ 100 nm as in the other potassium solutions. These unexpected phenomena were explained by the proposed mechanisms.
Collapse
Affiliation(s)
- Ko Higashitani
- Department of Chemical Engineering, Kyoto University-Katsura , Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kouta Nakamura
- Department of Chemical Engineering and Materials Science, Doshisha University , Kyotanabe, Kyoto 610-0321, Japan
| | - Tomonori Fukasawa
- Department of Chemical Engineering, Hiroshima University , Higashi Hiroshima, Hiroshima 739-8527, Japan
| | - Katsumi Tsuchiya
- Department of Chemical Engineering and Materials Science, Doshisha University , Kyotanabe, Kyoto 610-0321, Japan
| | - Yasushige Mori
- Department of Chemical Engineering and Materials Science, Doshisha University , Kyotanabe, Kyoto 610-0321, Japan
| |
Collapse
|
4
|
Higashitani K, Nakamura K, Shimamura T, Fukasawa T, Tsuchiya K, Mori Y. Orders of Magnitude Reduction of Rapid Coagulation Rate with Decreasing Size of Silica Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5046-5051. [PMID: 28423897 DOI: 10.1021/acs.langmuir.7b00932] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The modification of the classical Smoluchowski theory for the rapid coagulation rate of colloidal particles, which takes account of the effect of the squeezing flow between colliding particles, has been widely accepted because it predicts experimental results adequately. However, it is not clear whether the modified theory, in which the coagulation rate is independent of the particle size, is applicable even to nanoparticles in solutions. In the present study, the rapid coagulation rates of silica particles in various 2 M chloride and 1 M potassium solutions were measured by using a low-angle light-scattering apparatus, and the dependence of rapid coagulation rate on the particle diameter, Dp, was investigated extensively. It was clearly shown that the rapid coagulation rate of spherical silica particles reduces by the orders of magnitude with decreasing particle size at Dp ≤ 300 nm, whereas it coincides with the value predicted by the modified theory at Dp ≥ 300 nm. A possible mechanism is proposed, and an analytical equation, which predicts the dramatic reduction in the rapid coagulation rate with decreasing particle size, is derived.
Collapse
Affiliation(s)
- Ko Higashitani
- Department of Chemical Engineering, Kyoto University-Katsura , Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kouta Nakamura
- Department of Chemical Engineering and Materials Science, Doshisha University , Kyotanabe, Kyoto 610-0321, Japan
| | - Takuya Shimamura
- Department of Chemical Engineering and Materials Science, Doshisha University , Kyotanabe, Kyoto 610-0321, Japan
| | - Tomonori Fukasawa
- Department of Chemical Engineering, Hiroshima University , Higashi Hiroshima, Hiroshima 739-8527, Japan
| | - Katsumi Tsuchiya
- Department of Chemical Engineering and Materials Science, Doshisha University , Kyotanabe, Kyoto 610-0321, Japan
| | - Yasushige Mori
- Department of Chemical Engineering and Materials Science, Doshisha University , Kyotanabe, Kyoto 610-0321, Japan
| |
Collapse
|