Characterization of TiO2 nanoparticle suspensions in aqueous solutions and TiO2 nanoparticle retention in water-saturated columns packed with glass beads

In this experimental work, various suspensions of titanium dioxide (TiO2) nanoparticles (NPs) were carefully characterized, and their transport in columns packed with glass beads were thoroughly investigated. All NP suspensions were prepared with rutile-anatase and anatase TiO2. Two different methods were used for the preparation of aquatic suspensions of TiO2 NPs at relatively low concentrations. The average particle size and zeta potential of each suspension were estimated in order to investigate the effect of pH and sonication time on TiO2 NP agglomeration. Finally, transport experiments of the various suspensions of anatase TiO2 NPs were conducted. The concentration and particle size of the NPs were measured periodically at the column outlet. Also, the accumulated mass of TiO2 NPs retained in the column was determined. The experimental data suggested that NP agglomeration decreases with increasing solution pH and decreasing NP concentration. Also, it was shown that a substantial percentage of the anatase TiO2 NPs injected into the experimental column were retained within the column packing due to agglomeration, and that mass recovery is increasing with decreasing NP size and increasing injected concentration. (C) 2014 Elsevier B.V. All rights reserved.