PFAS Flashcards
What is a PFAS what are the two different categories that find under this term?
PFAS = per- and polyfluoroalkyl substances; contain a perfluoralkyl moeity within the molecule
- perfluroalkyl substances: no H, unless theyre associated with a specific funcitonal group
- polyfluoroalkyl substances: at least one carbon with hydrogens bound to it
how can fluorination affect the properties of organic compounds?
- less environemntal reactivity
- more volatile (interacts less with itself)
- more acidic (Fs stabalize charge)
Name some PFAS applications
- teflon in nonstick pans
- detergents
- flame retardants
- personal care products
- water/oil repellent
- pesticides
what two analytical methods are used to measure PFAAs?
- electrospray ionization-mass spectrometry
- liquid chromatography
What are the two main types of perfluoroalkyl acids (PFAAs), what are the properties of PFAAs?
- types = carboxylic and sulfonic acids (PFCAs and PFSAs)
- lipophobicity –> do not bioaccumulate in fat but rather protein rich compartments (organs, blood)
- shorter chain PFAAs are more water soluble than longer chains
How do PFAS get into water sources?
- direct emissions: spills, firefighter training, pesticide additives, WWTPs, chemical industry
- transport: ocean currents, air masses, WWTP sludge reuse, ground water, moving through soil
Describe the persistence of PFCAs and PFSAs
- no relevant environemental transformation reactions
- build up in the environment
- “forever chemicals”
can we use logKow as a predictor for bioaccumulation for PFAS?
no - doesn’t follow classical prediction methods
Describe two propeties of PFAAs and bioaccumulation in fish
- longer chain –> greater BCF and BAF
- SAs bioaccumulate more than CAs
what are some sources of point source contamination?
- airports and army bases
- fluoropolymer manufacturing plants
- fabric manufacturing and upholstery
for PFSA and PFCA, state if its found more in the sediment or water compared to the other
sediment = more PFSAs
water = more PFCAs
how can PFAS go through LRT?
- movement on partciles
- oxidation of volatile PFAS to PFCAS and other acids that will deposit via dry or wet deposition
what are the main polyfluronated PFAS compounds that form PFCAs? How are they produce? How are they named? what happens when they go under atmospheric oxidation?
- flurotelomer compounds
- produced with even number of carbons (two non-fluroinated, reamined perfluorinated)
- names as X:2 fluorotelomer, where X = number of perfluorinated carbons
- oxidation –> formation of perfluorinated adelhyde
what do perfluorinated aldehydes produce under low NOx conditions?
1:1 ratio of odd:even carbon chain length PFCAs
how can you tell if PFCAs found in the environment derived from a fluortelomer source?
1:1 odd/even ratio of PFCAs
