Dr Thi Song Thao Le

Postdoctoral Researcher

The University of New South Wales

Dr. Thao Le is currently a postdoctoral research at the University of New South Wales (UNSW), Sydney. She has expertise in water treatment, catalyst synthesis, and environmental fate of contaminants. She has intensive experience to work in the laboratory for investigating the air-water interfacial adsorption of per- and polyfluoroalkyl substances (PFAS) and developing the models to predict the environmental fate of PFAS. She also has experiences in a range of water treatment technologies (e.g., conventional and heterogeneous (nZVI) Fenton’s oxidation, photocatalysis, and porous materials/activated carbon adsorption) for organic contaminants removal (e.g., 1,2-dichloroethane and textile dyes). After her PhD award in mid2021, she has continued to work closely with Prof. Denis O’Carroll at UNSW as a postdoc and she has conducted experiments to investigate the removal of PFAS using different technlogies including (electro-) chemical reduction and ion exchange.

Prediction of the air-water interfacial adsorption of per- and polyfluoroalkyl substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) are a class of emerging contaminants that are widespread in the environment with broad human health impacts. As such, understanding the mechanisms that control the fate and transport of PFAS compounds is of particular interest. Air-water interfacial adsorption is an important environmental process that contributes to PFAS fate and transport. It is well known that interfacial behaviour of PFAS is strongly impacted by the molecular chemical structures (i.e., carbon chains and functional groups) and environmental conditions (e.g., salinity). However, the diversity of PFAS chemical structure challenges the experimentation to understand PFAS interfacial behaviour. Therefore, the aim of this thesis is to develop quantitatively predictive models to predict the interfacial behaviour for a wide range of environmentally relevant PFAS with differing composition and concentration of inorganic salts. In the first part of this thesis, a group contribution model was developed to predict the interfacial affinity for a wide range of PFAS compounds based on the chemical structure. In the next part of this thesis, a new mass-action law UNSW-OU model was developed to predict the air-water interfacial affinity of PFAS at different salt concentrations from 0 to 0.5 M. The model also applied in the presence of multiple monovalent and divalent salt components. As salts are ubiquitous, and vary from site to site, a small change in salt concentration or composition would have a substantial impact on PFAS interfacial behaviour. Therefore, the ability to calculate interfacial affinity in different salt conditions is important to achieve accurate predictions for PFAS transport in the vadose zone.