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Water Science & Technology Vol 67 No 1 pp 147–151 © IWA Publishing 2013 doi:10.2166/wst.2012.545

Dispersion and stability of titanium dioxide nanoparticles in aqueous suspension: effects of ultrasonication and concentration

J. Qi, Y. Y. Ye, J. J. Wu, H. T. Wang and F. T. Li

College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, UNEP-Tongji Institute of Environment for Sustainable Development, Tongji University, Shanghai 200092, China E-mail: hongtao@tongji.edu.cn


ABSTRACT

The increasing applications of titanium dioxide (TiO2) nanoparticles raise concerns about their potential environmental impacts. To investigate the fate and transport of TiO2 nanoparticles in aqueous suspension, ultrasonication is widely used for the dispersion of TiO2 nanoparticles in laboratory-scale studies. There is a pressing need for detailed information on the dispersion and stability of TiO2 nanoparticles. This study investigated the change of size, zeta potential, and pH of TiO2 nanoparticles aqueous suspension under different conditions of ultrasonication and concentrations. It was found that the hydrodynamic diameter of TiO2 nanoparticles decreased with increasing suspension concentration and remained stable for more than 1 hour after sonication, which is enough for experimental research. The pH decreased with increasing nanoparticles concentration. Ultrasonication remarkably improved zeta potential to be above 15 mV for all the samples. Therefore, 20 minutes of ultrasonication (180 W) is sufficient for the dispersion of this rutile TiO2 nanoparticles suspension, which can remain stable for more than 1 hour. However, the optimum sonication time for TiO2 nanoparticles dispersion is influenced by many factors, such as TiO2 nanoparticles concentration, solution chemistry, and sonicator parameters.

Keywords: concentration; dispersion; hydrodynamic diameter; TiO2 nanoparticles; ultrasonication


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