Poster Presentation 24th Australian Conference on Microscopy and Microanalysis 2016

Field flow fractionation: A powerful technology for nanoparticle characterisation in aqueous media (#275)

Maitreyee Roy 1 , Laura Chekli 2 , Leonard Tijing 2 , Erica Donner 3 , Enzo Lombi 3 , Hokyong Shon 2
  1. School of Optometry and Vision Science , The University of New South Wales, Sydney, NSW 2052, Australia
  2. School of Civil and Environmental Engineering , University of Technology, Sydney, NSW, 2007, Australia
  3. Centre for Environmental Risk Assessment and Remediation, University of South Australia, Adelaide, SA 5095, Australia

In the last decade, the use of engineered nanoparticles is rapidly expanding across the field of nanotechnology and has led to large-scale production and widespread commercialisation of nano-products. Titanium dioxide nanoparticles (TiO2 NPs) are currently one of the most prolifically used nanomaterials, finding applications in paints, cosmetics, catalysts and food colorants. The prevalent use of TiO2 NPs means that there is a high potential for them to enter the environment raises concerns about contamination, both by the nanoparticles themselves and by their potential to co-transport sorbed contaminants into surface and ground waters. Accurate and reliable characterisation of nanoparticles is crucial to underpin studies of their toxicological and environmental impacts.

The most relevant properties for such studies include the number/mass concentration, chemical composition, particle size distribution, agglomeration/aggregation state, surface charge and surface chemistry. Characterisation of these parameters in nanoscale systems presents numerous challenges, including determining the appropriate quantity to be measured for a given application, measurement of particle systems with complex size distributions, accounting for matrix effects, and distinguishing chemical compositions. Field Flow Fractionation (FFF) is emerging as a powerful tool for characterising nanoparticles in complex matrices. FFF is a high resolution elution technique that separates suspension constituents based on hydrodynamic size.

In this study, we used a multi-method approach combining light scattering and FFF techniques to assess both the aggregation behaviour and aggregate structure of TiO2 NPs in different river waters. Results showed that both the aggregate size and surface-adsorbed dissolved organic matter (DOM) were strongly related to the initial DOM concentration of the tested waters suggesting that aggregation of TiO2 NPs is controlled by the presence and concentration of DOM. The conformation of the formed aggregates was also found to be strongly related to the surface-adsorbed DOM with increasing surface-adsorbed DOM leading to more compact structures.