Retention and Transport of Silica Nanoparticles in Saturated Porous Media: Effect of Concentration and Particle Size

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• 作者：Chao Wang ; Aparna Devi Bobba ; Ramesh Attinti ; Chongyang Shen ; Volha Lazouskaya ; Lian-Ping Wang ; Yan Jin
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：July 3, 2012
• 年：2012
• 卷：46
• 期：13
• 页码：7151-7158
• 全文大小：397K
• 年卷期：v.46,no.13(July 3, 2012)
• ISSN：1520-5851

文摘

Investigations on factors that affect the fate and transport of nanoparticles (NPs) remain incomplete to date. In the present study, we conducted column experiments using 8 and 52 nm silica NPs to examine the effects of NPs鈥?concentration and size on their retention and transport in saturated porous media. Results showed that higher particle number concentration led to lower relative retention and greater surface coverage. Smaller NPs resulted in higher relative retention and lower surface coverage. Meanwhile, evaluation of size effect based on mass concentration (mg/L) vs particle number concentration (particles/mL) led to different conclusions. A set of equations for surface coverage calculation was developed and applied to explain the different results related to the size effects when a given mass concentration (mg/L) and a given particle number concentration were used. In addition, we found that the retained 8 nm NPs were released upon lowered solution ionic strength, contrary to the prediction by the Derjaguin鈥揕andau鈥揤erwey鈥揙verbeek (DLVO) theory. The study herein highlights the importance of NPs鈥?concentration and size on their behavior in porous media. To the best of our knowledge, it is the first report of an improved equation for surface coverage calculation using column breakthrough data.