Characterization of PFAS air emissions from thermal application of fluoropolymer dispersions on fabrics

Figures & data

Figure 1. String Reactor diagram with sketch of sampling apparatus and insert of pulling mechanism (not to scale). Insulation shown on the middle port only for illustration but is present on all exposed quartz.

Table 1. Fabric coating simulator settings for static experiments (constant settings) and dynamic experiments (varying furnace 3 fiber exit temperature).^a

	Temperatures °C
	Furnace 1	Furnace 2		Furnace 3		Fiber		Air	Dispersion use rate
	Air exit	Air exit	Setpoint	Air exit	Fiber exit	Speed cm/min	Residence time sec	Flow L/min	g/min
Static experiments^b
Water	80±3	142±11	721	362±35	370±9	119	85	9.8	1.1±0.1
Water + Tergitol	77±7	127±22	721	318±47	363±5	119	85	10.0	1.8±0.2
Water + Tergitol + 6:2 FTOH	63±10	120±13	721	324±22	347±12	119	85	9.6	1.9±0.3
PTFE DISP 30	95±3	160±4	721	397±12	381±6	119	85	10.1	3.3±0.1
PTFE DISP 30 - Low Temperature	81±11	142±4	404	230±18	252±3	69	146	12.0	1.6±0.3
FEPD 121 - Low Temperature	80±2	123±2	427	237±7	255±9	69	146	10.1	1.9±0.1
Dynamic experiments^c
Water + Tergitol + 6:2 FTOH	82±1	148±5	316-721	162-398	196±7-399±5	69	146	9.0	-
FEPD 121	76±14	160±21	316-721	189-391	192±2-469±11	69	146	9.1	-

^aFurnace 1 and Furnace 2 were set to 204 °C and 316 °C, respectively, calibrated to produce 100 °C and 190 °C fiber exit temperatures (based on optical pyrometry), respectively, using water. Air residence times were approximately 2-3 sec.

Furnace 3 was set to 721 °C, but reduced in later Low Temperature experiments as indicated (average temperatures ± standard deviations).

^bStatic experiments included canister, TD tube, and real-time CIMS and PTR sampling.

^cDynamic experiments included real-time CIMS and PTR sampling.

Table 2. Canister GC-MS data for static Water-Tergitol-6:2 FTOH experiments (ppbv).^a,b

		Water			Water + Tergitol			Water + Tergitol + 6:2 FTOH
PFAS	Formula	Furnace 1	Furnace 2	Furnace 3	Furnace 1	Furnace 2	Furnace 3	Furnace 1	Furnace 2	Furnace 3
Hexafluoroethane	C2F6	0.3, ND^c
Chlorodifluoromethane	CHClF2	0.3, 1.0	0.6, 0.6	0.6, 0.6	0.6, 0.6	0.6		0.6, 0.6	0.9
Trichlorofluoromethane	CCl3F	0.3, 1.3	1.0, 1.2	1.0, 1.0	1.3, 1.2	1.2	0.6, 0.9	0.9, 0.9	1.2, 0.6	0.3
Fluoromethane	CHF3							0.9, ND
1,1,1,2-Tetrafluoroethane	C2H2F4		0.6, ND					0.6, ND
Pentafluoroethane	C2HF5		0.3							17.3, 7.5
Trifluoromethane	CHF3									24.0, 9.8
Tetrafluoroethene (TFE)	C2F4									353.2, 165.6
Hexafluoropropene	C3F6									13.3, 6.0
1H-Heptafluoropropane	C3HF7									5.6, 3.0
1H-Nonafluorobutane	C4HF9									2.4, 1.2
1H-Perflluoropentane	C5HF11									4.3, 2.7
1H-Perfluorooctane	C8HF17									52.3, 20.8

^aValues are corrected for sample dilution to represent concentrations in the furnaces. Correction factors: Water = 8.0, Water+Tergitol = 7.7, Water+Tergitol+6:2 FTOH = 7.8.

^bDuplicate experiment values separated by commas.

^cND - not detected in replicate sample.

Table 3. Fluorinated compounds detected in thermal desporption (TD) tube samples (static experiments).^a

					Water + Tergitol + 6:2 FTOH
PFAS	Formula	CAS Number	Furnace	Instrument^b	Number of Detects^c
6:2 FTOH	C8H5F13O	647-42-7	1	A&B	3/3
			2	A&B	4/4
			3	A&B	3/3
Perfluoro-2-methylbutane	C5F12	594-91-2	2	B	2/3
1H,1H,2H-perfluoro-1-octene	C8H3F13	25291-17-2	3	A&B	3/3
Unidentified PFAS	C8H3F12O^d		1	B	3/3
			2	B	3/3
			3	B	3/3
Fluoroethene	C2H3F	75-02-5	3	A	2/3
					PTFE DISP 30	PTFE DISP 30 -	FEPD 121 -
						Low Temp	Low Temp
PFAS	Formula	CAS Number	Furnace	Instrument^b	# of Detects	# of Detects	# of Detects
Fluoroether E1^e	C5HF11O	3330-15-2	1	B	1/3	3/3	3/3
			2	B	3/3	2/3	3/3
			3	B	3/3	3/3	3/3

^aNo fluorinated compounds were observed in the Water or Water+Tergitol TD tube samples.

^bInstruments used - A: TD-GC-Quadrupole-MS, B: TD-GC-Orbitrap-MS

^cNumber of detects per number of samples collected.

^dC₈H₃F₁₂O was assigned a chemical formula by exact mass and does not have a spectral library match to assign a chemical structure.

^eE1 is the trade name for 1,1,1,2,2,3,3-heptafluoro-3-(1,2,2,2-tetrafluoroethoxy)propane.

Figure 2. Mass defect visualizations of CIMS data from each port during PFAS-free H₂O (left column), H₂O + Tergitol (center column), and H₂O + Tergitol+6:2 FTOH (right column).

Figure 3. CIMS measurements from the Water + Tergitol + 6:2 FTOH   experiment.

Table 4. Canister GC-MS data for static dispersion experiments (ppbv).^a,b,c

		PTFE DISP 30			PTFE DISP 30 - Low Temperature			FEPD 121 - Low Temperature
PFAS	Formula	Furnace 1	Furnace 2	Furnace 3	Furnace 1	Furnace 2	Furnace 3	Furnace 1	Furnace 2	Furnace 3
Trifluoromethane	CHF3									16.6
Tetrafluoroethene (TFE)	C2F4			9.4	1.3, 0.6	1.3, 1.3	2.0, 1.3			0.3
Hexafluoropropene	C3F6			1.1						7.2, 9.9
Octafluorocyclobutane	C4F8		25.1	45.0	25.0, 25.3	27.5, 26.1	26.0, 25.6	1.6, 2.2	16.2, 8.4	7.6, 19.3
Fluoroether E1	C5HF11O	361.2	1022.0	2062.4	1084.2, 1078.0	5969.3, 4416.3	462.6, 303.9	63.7, 84.4	1111.7, 580.2	389.9, 375.7

^aValues are corrected for sample dilution to represent concentrations in the furnaces. Correction factors: PTFE DISP 30 = 8.1, PTFE DISP 30 Low Temperature = 7.9, FEPD 121 Low Temperature = 8.0.

^bDuplicate experiment values separated by commas.

^cWater blanks included <2 ppbv detects for several C1-C4 PFAS. Water blanks and <2 ppbv PFAS removed to simplify presentation.

Table 5. Calculated emission factors (EF).^a

Dispersion Experiment	Furnace	EF (µg/g 6:2 FTOH)
		ƩC1-C8 By-products	Tetrafluoro-ethene (TFE)
Water + Tergitol + 6:2 FTOH	3	5670.8, 2598.4	3077.3, 1442.7
Dispersion Experiment	Furnace	EF (µg/g dispersion) Fluoroether E1
PTFE DISP 30	1	15.1
	2	42.7
	3	86.1
PTFE DISP 30 Low Temperature	1	86.4, 85.9
	2	475.8, 352.0
	3	36.9, 24.2
FEPD 121 Low Temperature	1	4.4, 5.8
	2	76.3, 39.8
	3	26.7, 25.8

^aEFs calculated from Tables 2 and 4. Duplicate experiment values separated by commas.

Figure 4. Recorded temperatures from temperature ramp experiments for (A) Water + Tergitol + 6:2 FTOH and (B) FEPD 121. Black text on graphs represents temperature setpoints of the temperature controller in degrees Celsius. Note: String broke during 721°C setpoints as indicated by gray box and “S.B.”.

Figure 5. CIMS measurements from the Water + Tergitol + 6:2 FTOH temperature ramp.

Figure 6. CIMS (top panel) and PTR-MS (bottom panel) measurements from FEPD 121 temperature ramp experiment.

Data availability statement

The data that support the findings of this study are openly available on ScienceHub at http://doi.org/10.23719/1527849 reference number D-g4fk.