Titanium dioxide nanomaterials, synthesis, stability and mobility in natural and synthetic porous media

摘要

Highly ordered, stable and reproducible TIO(_2) NMs were synthesized using different precursors and alcohol mixtures. Various shapes of TIO(_2) including spherical NPs with shape factor of 0.9 or more, nanocubes, nanorods and ellipsoids were successfully fabricated. Spherical round anatase and rutile ellipsoids were selected and stabilized with different surfactants including PEG, PVP, sodium citrate and SRFA. Sodium citrate and SRFA proved to be the best stabilizing agents as compared to other surfactants used. udThe stabilized NMs were tested for their aggression kinetics in the presence of mono and divalent electrolytes (NaNO(_3), NaCl, CaN(_2)O(_6), CaCl(_2)). The aggregation kinetic studies showed that rutile ellipsoids behaved well against different mono and divalent cations. The CCC's observed for sodium citrate stabilized NMs were significantly higher than SRFA stabilized NMs, showing that sodium citrate is a better stabilizing agent than SRFA. udThe SRFA and sodium citrate stabilized NMs were studied for porous media column transport. The mobility of the rutile ellipsoids was greater than spherical anatase. Bare anatase NPs gave no breakthrough and the NPs clogged both the sandstone and glass bead columns; while bare rutile ellipsoids gave nearly 100% breakthrough curves. Only 40% or less NPs were released from sandstone columns. More release of NPs with SRFA flush is also important as it reflects the ultimate fate and behaviour of TiO(_2) NPs in natural environment which is rich in humic substances.