Adsorption and desorption processes on polymers in aquatic systems [thesis]

Tobias Horst Uber, DuEPublico: Duisburg-Essen Publications Online, University Of Duisburg-Essen, Torsten Claus Schmidt
The sorption behaviour of high-density polyethylene (HDPE) and some other plastic materials in the aquatic environment with non-ionic organic compounds has already been studied to some degree although there is not yet a systematic approach to determine the sorption properties for a larger compound set. With the steady increase of interest on plastic materials in the environment, especially due to micro plastic particles (MP) or the great garbage patches, an increased demand for estimating
more » ... on behaviours of those materials is mandatory. This is not only the case for HDPE but also for other plastic materials such as polystyrene (PS), low density polyethylene (LDPE) or polyacrylate (PA). To this end, this thesis aims at a systematic investigation of sorption behaviour of selected plastic materials by use of probe sorbates in an aquatic environment. Sorption batch experiments with HDPE material used for water pipes and selected probe sorbates were carried out in a three-phase system (air/HDPE/water) covering an aqueous concentration range of at least three orders of magnitude. Sorption in the concentration range below 10-2 of the aqueous solubility was found to be nonlinear and the Freundlich model was used to account for this non-linearity. Multiple regression analysis (MRA) using the determined distribution coefficients and literature-tabulated sorbate descriptors rendered robust ppLFER models for all three concentration levels. Sorption was found to be dependent on polymer density and crystallinity by the ppLFER model and the derived ppLFER model described sorption more accurately than commonly used single-parameter predictions (spLFER). A comparison of predicted data to experimental data from literature and this work demonstrated the strength of the ppLFER, based on the training set over several orders of magnitude. Batch experiments with PS were done with the same experimental approach but isotherms were evaluated with additional sorption models. The Freundlich fit rendered again the most robust data and it [...]
doi:10.17185/duepublico/70287 fatcat:qtn5kvktq5fbfgyxy3o4n6xxfe