A combined computational and experimental approach to characterising the adsorption of hydrophilic pollutants onto Oasis® HLB
Creators: name: Close, Christine
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 340109
subject: Separation science
classificationCode: 370104
subject: Atmospheric composition, chemistry and processes
classificationCode: 4104
subject: Environmental management
classificationCode: 410404
subject: Environmental management

description: Hydrophilic contaminants are regularly released into the aquatic environment from anthropogenic sources such as wastewater treatment plants. Whilst they are unlikely to bio-accumulate within the environment like their hydrophobic counterparts, due to their continual release, a number of these compounds have shown to have a detrimental impact on environmental health and potentially human health, even at trace levels. Traditional environmental monitoring programmes involve the collection of multiple grab samples which can be both an expensive and a laborious process. Additionally, compounds under investigation are not always released into the environment at regular intervals. This therefore can lead to a hit and miss approach when it comes to monitoring their impact on the environment.<br><br>Passive sampling has the ability to overcome these issues by monitoring a body of water for a predetermined period of time at the end of which, a time-weighted average concentration for these compounds of interest can be generated. A number of different passive samplers have been developed over the last 20 years with the passive sampler – the polar organic chemical integrative sampler (POCIS) being developed specifically to sample for hydrophilic contaminants. Whilst the mechanisms of interaction between the sampler’s receiving phase and the contaminants have been fully elucidated for common hydrophobic samplers, the same cannot be said for the hydrophilic samplers such as POCIS.<br><br>The aim of the research presented in this dissertation was to elucidate potential mechanisms of interactions between three distinct classes of hydrophilic contaminants and a widely used POCIS matrix – Oasis HLB. In order to achieve this objective, both experimental and theoretical investigations were undertaken.<br><br>The experimental component of this work involved performing batch adsorption studies to determine the adsorption characteristics of the selected hydrophilic compounds and Oasis HLB. A sampling rate study was also conducted to determine the uptake rate value for one of the selected classes of compounds.<br><br>The theoretical investigations that were undertaken for this dissertation involved the use of hybrid-density functional theory (DFT) calculations in order to determine the type and strength of the interactions that can take place between the compounds of interest and the selected sorbent (Oasis HLB).<br><br>Using computational chemistry methods for the purposes stipulated above, is a novel approach and one that is expected to help further establish the validity of sorbent based passive samplers such as POCIS by providing useful information about how analytes and sorbents interact.<br>