As nanotechnologies become more widely used, titania nanoparticles are being released to the subsurface environment via wastewater sludge applications. Titania nanoparticles are not only toxic to organisms in the environment, but recent studies revealed that they may also serve as carriers of hydrophobic organic contaminants and affect their fate and distribution in the subsurface environment. The mobility of titania nanoparticles varies depending on nanoparticle morphology characteristics, pH and the ionic strength of solutions, flow velocity, nanoparticle concentration, and the presence of surfactant or natural organic matter. Analogous to findings for natural and engineered carbonaceous nanoparticles, titania nanoparticles may enhance the transport of hydrophobic organic contaminants in porous media. However, to prove this hypothesis, further research is necessary. Thus experiments examining the impacts of titania nanoparticle on the hydrophobic organic matter transport in porous media were designed, which consist of three different sets of column experiments. These experimental sets will investigate the effects of the presence of titania nanoparticles, the size of nanoparticles and the organic carbon content in soil, respectively. Due to the estimation of the potential for the titania nanoparticles to facilitate organic contaminant transport, the experiment results are expected as: (a) the presence of titania nanoparticles will enhance the organic contaminant transport in porous media; (b) smaller nanoparticles will adsorb more organic contaminants and enhance their transport as the result of the increasing specific surface area; (c) soil containing higher organic matter content will compete for the adsorption of organic contaminants and retard their facilitated transport by titania nanoparticles.
Laboratory observations and mathematical modeling of colloid-facilitated contaminant transport in chemically heterogeneous systems
