Perfluorinated Compounds Are Very Resistant to Breakdown in the Environment Due to The

Abstract

Perfluorinated compounds are very resistant to breakdown in the environment due to the strength of the C – F bond. In this project the ability of solar radiation to degrade perfluorinated compounds was studied. This was done in the lab by emulating conditions from a field experiment led by S. Taniyasu of which the results were published in 2013[1]. The paper containing these results claimed that perfluorinated compounds can be degraded by sunlight. For the new lab experiment, samples of perfluorinated carboxylic acids (PFCAs) were made in 2% methanol in water, in borosilicate tubes. These tubes were irradiated for more than 50 days by an 8 watt UV lamp emitting radiation in the range 280-380 nm which contains the UV-B region (280-320 nm). Adsorption of PFCAs to the wall of the borosilicate container was tested by placing similar samples in the dark. Adsorption to polypropylene was also tested because this material is used for storing subsamples at different data points. The samples were separated by ultra-high performance liquid chromatography. Quadrupole time-of-flight mass spectrometry was used for detection and identification of the compounds. This is a high resolution method which means that masses can be measured with very high accuracy making identification of compounds easier. A list of suspects was used to screen the samples for expected transformation products. This resulted in the finding of transformation products for long chain PFCAs (PFDA and PFTDA) but not for short chain PFCAs (PFBA, PFHpA and PFOA). The samples were also screened for unknown, unexpected compounds but this had no result. Besides the new laboratory samples, some field samples from Taniyasu’s experiment were screened but no degradation products were found. In the adsorption experiments it was found that PFCA concentrations were reduced strongly in borosilicate tubes. This might be the reason that not all loss of starting material can be explained by the formation of transformation products, which was also observed by Taniyasu.