Prospects of complete mineralization of per- and polyfluoroalkyl substances by thermal destruction methods

Per- and polyfluoroalkyl substances (PFAS) are a class of man-made chemicals found in various consumer goods due to their unique properties. Failing abatement techniques and improper waste management result in the release of these chemicals into the environment (diluted in soil, water, and air) causing detrimental effects to human health. Therefore, a variety of novel technologies is currently under development to destroy PFAS. Thermal destruction using active materials has the potential to achieve full mineralization of the fluorine atoms. Nevertheless, two major challenges need to be overcome to remove doubts about the destruction efficiency and enable further optimization: 1) which combination of process conditions/dedicated destruction techniques/active materials can lead to complete mineralization and 2) incomplete mass balance closure by currently employed analysis techniques.

Owing to the complexity of matrices and the myriad of intermediate and incomplete PFAS degradation compounds, a single ‘fit-for-all’ analytical standard/method likely does not exist. Therefore, a holistic combination of targeted, semi-targeted, and nontargeted analyses is required to obtain maximally comprehensive insight into the PFAS degradation compounds. The volatile degradation products can be analyzed via comprehensive two-dimensional gas chromatography coupled with high-resolution mass spectrometry (HRMS). Nonvolatiles can be trapped and analyzed via ultraperformance liquid chromatography coupled with high-resolution mass spectrometry and triple-quadrupole mass spectrometry, and a myriad of elemental analysis techniques. In addition, also the remaining solid residue needs to be extracted and analyzed via specific methods to quantify the PFAS content in the solid residues.