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Journal of Nanomaterials
Volume 2015, Article ID 851928, 10 pages
http://dx.doi.org/10.1155/2015/851928
Research Article

Dominating Role of Ionic Strength in the Sedimentation of Nano-TiO2 in Aquatic Environments

1School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China
2School of Civil and Environmental Engineering, Shenzhen Polytechnic, Shenzhen 518055, China
3Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China

Received 31 July 2015; Accepted 27 September 2015

Academic Editor: Lutz Mädler

Copyright © 2015 Guang’an He et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Various factors affect the sedimentation behavior of nanotitanium dioxide (n-TiO2) in water. Accordingly, this study aimed to select the dominating factor. An index of sedimentation efficiency related to n-TiO2 concentration was applied to precisely describe the n-TiO2 sedimentation behavior. Ionic strength (IS), natural organic matter (NOM) content, and pH were evaluated in sedimentation experiments. An orthogonal experimental design was used to sequence the affecting ability of these factors. Furthermore, simulative sedimentation experiments were performed. The n-TiO2 sedimentation behavior was only affected by pH and NOM content at low levels of IS. Moreover, divalent cations can efficiently influence the n-TiO2 sedimentation behavior compared with monovalent cations at fixed IS. Seven different environmental water samples were also used to investigate the n-TiO2 sedimentation behavior in aquatic environments. Results confirmed that IS, in which divalent cations may play an important role, was the dominating factor influencing the n-TiO2 sedimentation behavior in aquatic environments.