Table 3. Summarizing Removal Mechanism, Advantages and Disadvantages of Treatment Techniques for Removal of PFAS Isomers^a.

technology	type of treatment	removal/breakdown mechanism	PFAS studies	difference in removal for br-PFAS relative to L-PFAS	removal summary	advantages	disadvantages
GAC filtration13−15,19,20	sequestration	adsorption-hydrophobicity dependent	5 PFSAs, 13 PFCAs, 2 FOSAs, 2 FOSAAs, 2 FOSEs, 1 FTSA	8–29% ↓	br-PFAS showed earlier breakthrough/poor removal vs L-PFAS	cost-effective and good removal of hydrophobic L-PFAS	relatively poor removal/early breakthrough of br-PFAS, PFAS-concentrated waste stream
AIX18		adsorption-electrostatic interactions	6 PFCAs, 2 PFSAs		similar removal for br and L-PFAS	Isomerism did not impact removal efficiency.	fouling issues, high initial costs, PFAS-concentrated waste stream
AIX15			10 PFCAs, 3 PFSAs, 1 FOSA	0–5% ↓	L-PFOS showed better removal	preferential removal of L-PFAS
electrocoagulation87		Floc formation followed by sorption	5 PFCAs, 1 PFSA				relatively poor removal of br-PFAS, PFAS concentrated waste stream
eAOP74,88,89	destructive	oxidation by OH·	7 PFCAs, 3 PFSAs		similar removal for br and L-PFAS	Isomerism did not impact removal efficiency.	high initial costs (e.g., electrode materials)
E-beam/gamma irradiation17,90−92		reactions with oxidative/reductive species	1 PFSA, 1 PFCA, 1 FTS	∼78% ↑ (degradation)	br-PFAS preferentially degraded	can actually breakdown C–F bonds in br and L-PFAS	breaking down L-PFAS requires more energy.
				17–30% ↑ (rate constant)	L-PFAS showed more resistance to degradation		high energy requirements, capital costs
advanced reduction processes16,21,70,93		reactions with reductive species	7 PFSAs, 5 PFCAs, 3 FTS	20–87% ↑
photocatalyis94,95			PFOS	rate constants were 4–965× ↑
photodegradation69		direct reactions with UV irradiation	PFOS	7–170% ↑ (rate constants)

^aNote: Table created using previous studies that have compared the removal/degradation efficiencies of br and L-PFAS.