Subscriber access provided by - Access paid by the | UCSB Libraries
Novel Remediation and Control Technologies
Reductive Defluorination of Branched Per- and Polyfluoroalkyl Substances with Cobalt Complex Catalysts Jinyong Liu, Daniel J Van Hoomissen, Tianchi Liu, Andrew Maizel, Xiangchen Huo, Seth R. Fernández, Changxu Ren, Xin Xiao, Yida Fang, Charles Schaefer, Christopher P. Higgins, Shubham Vyas, and Timothy J. Strathmann Environ. Sci. Technol. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.estlett.8b00122 • Publication Date (Web): 28 Mar 2018 Downloaded from http://pubs.acs.org on March 28, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 17
Environmental Science & Technology Letters
1
Reductive Defluorination of Branched Per- and Polyfluoroalkyl Substances
2
with Cobalt Complex Catalysts
3 4 5
Jinyong Liu,*,†,‡ Daniel J. Van Hoomissen,§ Tianchi Liu,† Andrew Maizel,‡ Xiangchen Huo,‡ Seth R. Fernández,† Changxu Ren,† Xin Xiao,#,‡ Yida Fang,‡ Charles Schaefer,∆ Christopher P. Higgins,‡ Shubham Vyas,*,§ and Timothy J. Strathmann*,‡
6 7 8 9 10 11
†
12
Abstract
13
This
14
polyfluoroalkyl substances (PFASs) undergoing cobalt-catalyzed reductive defluorination
15
reactions. Experimental results and theoretical calculations reveal correlations between the extent
16
of PFAS defluorination, the local C−F bonding environment, and calculated bond dissociation
17
energies (BDEs). In general, BDEs for tertiary C−F bonds < secondary C−F bonds < primary
18
C−F bonds. A tertiary C−F bond adjacent to three fluorinated carbons (or two fluorinated
19
carbons and one carboxyl group) has a relatively low BDE that permits an initial defluorination
20
to occur. Both a biogenic cobalt-corrin complex (B12) and an artificial cobalt-porphyrin complex
21
(Co-PP) are found to catalytically defluorinate multiple C−F bonds in selected PFASs. In general,
22
Co-PP exhibits higher initial rate of defluorination than B12. Neither complex induced significant
23
defluorination in linear perfluorooctanoic acid (PFOA; no tertiary C−F bond) or a perfluoroalkyl
24
ether carboxylic acid (tertiary C−F BDEs too high). These results open new lines of research,
25
including (1) designing branched PFASs and cobalt complexes that promote complete
26
defluorination of PFASs in natural and engineered systems, and (2) evaluating potential impacts
27
of branched PFASs in biological systems where B12 is present.
Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States ‡ Department of Civil and Environmental Engineering and §Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States # Department of Environmental Science, Zhejiang University, Hangzhou 310058, China ∆ CDM Smith, 110 Fieldcrest Avenue, No. 8, Sixth Floor, Edison, New Jersey 08837, United States
study
investigates
structure-reactivity
relationships
1 ACS Paragon Plus Environment
within
branched
per-
and
Environmental Science & Technology Letters
28 29
Introduction
30
Since the original development in the 1940s, per- and polyfluoroalkyl substances (PFASs) have
31
been widely used in industrial and consumer products.1,
32
environment has been extensively documented.2-6 Substantial research efforts on the two C8
33
legacy compounds, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS),
34
have confirmed a variety of adverse health effects,7 leading to the phase-out of ≥C8 PFASs in
35
North America and Europe8 and the USEPA’s recent issuance of drinking water health advisory
36
levels for PFOA and PFOS.9,
37
sulfonic acids, perfluoroalkyl ether carboxylic acids, and other novel structures) have already
38
been detected in aquatic environments and are considered recalcitrant.11-15 Recent studies have
39
also indicated that the emerging PFASs exhibit variable toxicities and environmental
40
mobilities.11, 16-20 Still, knowledge on emerging PFASs remains limited.11, 21
41
Despite having received much less attention than linear PFASs, branched PFASs (Figure 1) have
42
also been extensively applied and detected in the environment. For example, perfluoro-3,7-
43
dimethyloctanoic acid (PFMe2OA) serves, along with linear PFASs, as an ingredient of well
44
treatment fluids.22 This compound is also on the “STANDARD 100 by OEKO-TEX” list,
10
2
Detection of PFASs in the global
New alternative PFASs (e.g., shorter chain carboxylic and
2 ACS Paragon Plus Environment
Page 2 of 17
Page 3 of 17
Environmental Science & Technology Letters
45
indicating its wide application in textile production,23 and it has been detected in European water
46
bodies.24 Perfluoroethylcyclohexane sulfonate (PFECHS)25 also contains two branched carbons
47
on the cyclic structure, and its detection in Canadian Arctic lakes has been attributed to its use in
48
aircraft anti-erosion fluid.26 Industrial PFOS products often contain variable fractions of
49
branched isomers, which have been detected in both environmental waters and human tissues.27,
50
28
51
backbone.29, 30 Recently reported perfluoroalkyl ether carboxylic acid pollutants such as GenX12
52
and its longer analog15 also contain branched structures.
53
The recalcitrance of PFASs to biological and chemical degradation is attributed to the high
54
stability of C−F bonds.31 However, Ochoa-Herrera et al.32 observed >70% fluoride ion (F−)
55
release from a mixture of branched PFOS isomers by reaction with B12 (a corrin-CoIII complex,
56
catalyst precursor) and TiIII citrate (reductant). More recently, Park et al.33 reported cleavage of
57
multiple sp3 C−F bonds from analytical standards of mono-branched PFOS with a –CF3 at the 3-,
58
4-, 5-, or 6-position (see the 6-brPFOS structure in Figure 1) using B12 and nanosized Zn0 as an
59
alternative reductant. Since B12 is an essential component for microorganisms and animals, these
60
findings suggest that reductive defluorination of branched PFASs could occur in natural
61
environments or biological systems. Furthermore, if the initial defluorination replaces one or
62
more F atoms with H atoms, additional defluorination mechanisms could be triggered. For
63
example, HF elimination from fluorotelomers (i.e., −CH2−CF2− into –CH=CF−) has been
64
observed both in vivo and abiotically in the environment,34, 35 and such a transformation could
65
significantly alter the toxicity of the PFASs.34 Hence, it is both scientifically intriguing and
66
practically imperative to further investigate critical structural factors determining Co-mediated
Typical branched PFOS isomers contain one or two −CF3 branching from the perfluorinated
3 ACS Paragon Plus Environment
Environmental Science & Technology Letters
Page 4 of 17
67
defluorination of branched PFASs. The findings of this work will help evaluate the fate of
68
emerging PFASs and aid in the design of less persistent and toxic PFASs.
69
Materials and Methods
70
Chemicals and solution preparation. PFASs (SynQuest Laboratories), B12 (Alfa Aesar) and
71
other cobalt species (Sigma-Aldrich), 12% TiCl3 solution (Acros Organics), and other chemicals
72
(Fisher Chemical) were used as received. Detailed chemical information (Table S1) and
73
preparation of stock solutions of PFASs, cobalt species, and TiIII citrate in carbonate buffer36 are
74
described in the Supporting Information (SI).
75
Defluorination reaction and sample analysis. The procedure was modified from Ochoa-
76
Herrera et al.32 In an anaerobic glove bag, a series of 9-mL serum bottles were loaded with 4 mL
77
of solution containing specific PFASs (0.1 mM), TiIII citrate (~36 mM) with carbonate buffer
78
(~40 mM), and cobalt catalyst (0.25 mM). More operational details are provided in the SI. Each
79
serum bottle was sealed and transferred to a 70°C oven. At designated reaction times, individual
80
reactors were sacrificed for analysis. Each reactor was used for a single measurement, such that a
81
typical reaction series of five time points (0, 1, 3, 7, and 15 days) began with five replicates of
82
each reaction mixture. Each reaction series was repeated at least twice. Due to the interference of
83
TiIII citrate matrix to the fluoride-selective electrode, F− release was analyzed by ion
84
chromatography.
85
chromatography−quadrupole time-of-flight mass spectrometer (LC−QToF-MS). Details of
86
instrumental analyses are provided in SI.
87
C‒F bond dissociation energy (BDE) calculation. BDEs of C‒F bonds in PFAS structures
88
(anion for carboxylic acids) were calculated using Grimme’s GD3-BJ empirical dispersion
Degradation
of
parent
PFASs
4 ACS Paragon Plus Environment
was
analyzed
by
liquid
Page 5 of 17
Environmental Science & Technology Letters
89
corrected37 hybrid density functional theory (DFT) at the B3LYP/6-311+G(2d,2p) level of
90
theory.38-41 Truhlar’s SMD solvent model was chosen to implicitly model the aqueous
91
environment.42 The BDE for each bond was calculated through Eq. (1):
92
∗ ∗ ∗ = [ ] + −
(1)
93
where H* represents the enthalpy of formation.
94
Results and Discussion
95
Initial experiments tested the defluorination of PFMe2OA (1), a well-defined branched structure,
96
at rate-optimized reaction conditions reported previously (pH 9.0 and 70°C).32 Defluorination
97
was evaluated by the concentration ratio of released F− ions to the F initially present in the PFAS
98
substrate. Significant defluorination occurred only in the presence of both TiIII and B12 (Figure
99
S1). Figure 2a shows that a maximum of 85% defluorination from 1 was achieved in 7 d.
100
Because LC−QToF-MS analysis indicated complete degradation of 1, this high defluorination
101
ratio corresponds to an average of sixteen of the nineteen F atoms within the PFMe2OA structure
102
being released as F−. According to the mechanisms proposed for Co-catalyzed dehalogenation
103
reactions (X = Cl and Br),43-45 TiIII reduces the CoIII in B12 to CoI, which then interacts with
104
either the carbon or halide (X) to cleave the C−X bonds. Assuming a similar mechanism for the
105
defluorination reactions, the turnover number (TON) for each Co center is estimated to be 6.5 for
106
the reaction with 1, demonstrating the catalytic nature of reaction. The TON could be further
107
increased for at least 10 times (i.e., TON=65) because elevating the concentration of 1 from 0.1
108
mM to 1.0 mM still achieved the same defluorination ratio. The reaction slowed at room
109
temperature (21 ± 2°C), but still resulted in at least 44% defluorination within 8 mo (Figure S2),
5 ACS Paragon Plus Environment
Environmental Science & Technology Letters
110
suggesting the potential for slow defluorination of branched PFASs in low redox potential
111
natural environments, where microorganisms employ B12 for dechlorination.46
112
To elucidate the relationship between PFAS structure and susceptibility to B12-catalyzed
113
defluorination, commercially available PFASs with different “branched structures” were reacted
114
with B12 and TiIII (Figure 2). It was soon realized that a simple classification as “branched” was
115
insufficient as a predictor for susceptibility to defluorination. For example, a branched
116
fluorotelomer acid 4 (Figure 2d) released negligible F− under the same reaction condition as 1.
117
In stark contrast, replacing the –CH2–CH2– moiety within the fluorotelomer structure with –
118
CF=CF– (2) led to the rapid and complete degradation of the parent compound within 1 day and
119
a maximum of 91% defluorination (an average of eight of the nine C−F bonds cleaved in each
120
molecule, Figure 2b). Cyclic 3 is a carboxylic acid analog of PFECHS. It contains one branched
121
carbon with two −CF2− and a –COOH neighbors. The parent compound was partially degraded
122
(70%), and the F− release from 3 corresponded to an average of three out of eleven F atoms in
123
each molecule (Figure 2c). In comparison, negligible F− release was observed from the cyclic
124
amine 6, in which the N atom can be considered as a “branched” point. Negligible F− release was
125
observed for the perfluoroalkyl ether compound 5 possessing two branched carbons. Hence, it
126
can be inferred that the local chemical environment surrounding the tertiary C−F is critical to
127
their reactivity with B12. No appreciable defluorination was observed in experiments with the
128
linear PFOA (7) and several shorter chain linear acids lacking branched carbon atoms (CF3SO3H,
129
CF3COOH, and CF3CF2COOH). LC–QToF-MS analysis showed no significant degradation of 7
130
for up to 30 days.
131
In comparison to the carboxylic acid 1, B12-catalyzed F− release was much slower for the
132
analogous telomer alcohol structure 8 (Figure 2f versus 2a), and the F− release from alcohol 9, 6 ACS Paragon Plus Environment
Page 6 of 17
Page 7 of 17
Environmental Science & Technology Letters
133
with only one branched carbon, was even slower (Figure 2g). The comparison between cyclic 3
134
and 10 also shows much slower defluorination from the telomer alcohol than from the carboxylic
135
acid (Figure 2h versus 2c). Degradation of alcohols in aqueous solution was not readily
136
observed by LC−QToF-MS. Reactions with these alcohols were also conducted with variable
137
headspace volumes (e.g., 9 mL liquid + 0 mL headspace versus 2 mL liquid + 7 mL headspace in
138
the sealed 9-mL bottles). All conditions yielded similar defluorination results, excluding the
139
possibility that the slower defluorination resulted from volatilization of alcohol substrates into
140
the headspace.
141
Calculated C−F bond dissociation energies (BDEs) provide further insights into mechanisms for
142
the initial step of defluorination. As shown in Figure 3, the general order of C−F BDEs is
143
tertiary < secondary < primary. The lowest secondary C−F bond BDE (451.9 kJ mol−1) in the 2-
144
position of 7 can be attributed to its proximity to –COOH. In 1, 8 and 9, secondary C−F bonds
145
adjacent to branched carbons have even lower BDEs (414.2 to 431.0 kJ mol−1). Importantly,
146
BDEs for tertiary C−F bonds within the structures for which defluorination was observed
147
(compound 1−3 and 8−10) range from 364.4 to 431.0 kJ mol−1, whereas higher BDEs ranging
148
from 431.4 to 443.9 kJ mol−1 were found in the two branched structures with no defluorination (4
149
and 5). The higher BDEs for those tertiary C−F bonds are due to the presence of relatively weak
150
electron-withdrawing hydrocarbon and oxo moieties nearby. We propose that the initial
151
defluorination steps occur at tertiary C−F bonds with low BDEs. Such weak bonds can dissociate
152
upon interaction with CoI. A Comparison of the three non-cyclic structures 1, 8, and 9 suggests a
153
rough correlation between the BDEs of the tertiary C−F bonds (1 < 8 < 9) and the reaction rates
154
of defluorination (1 > 8 > 9). Comparison of the cyclic 3 and 10 reveals a similar trend.
7 ACS Paragon Plus Environment
Environmental Science & Technology Letters
155
Compound 2 has two sp2 C−F bonds with high BDEs (478.2 and 477.8 kJ mol−1) and exhibited
156
rapid and extensive defluorination. In comparison to 1, the presence of sp2 C−F bonds seems to
157
promote defluorination. The bonding with the C=C double bond significantly weaken the tertiary
158
C−F bond (364.4 kJ mol−1, the lowest BDE among all structures). Similar results have been
159
reported by Im et al.,47 who reported B12-catalyzed defluorination of the only sp2 C−F in the
160
refrigerant HFO-1234yf (H2C=CF−CF3) yielding H2C=CH−CF3, and further defluorination of
161
one sp3 C−F in H2C=CH−CF3 yielding H2C=CH−CF2H. Additionally, sp2 C−F bonds can be
162
cleaved with H2 gas and a Rh/Al2O3 catalyst48, 49 while sp3 C−F bonds cannot. Defluorination
163
involving unsaturated bonds probably follows reaction mechanisms similar to the Co-catalyzed
164
dechlorination of chlorinated ethenes.43 Future studies are necessary for mechanistic elucidation.
165
In addition, the close BDE values for the two tertiary C−F bonds in 9 and 4 (431.0 versus 431.4
166
kJ mol−1) suggest that the neighboring atoms are also critical to initiate defluorination reactions.
167
The experimental results described above indicate that, B12-catalyzed defluorination requires a
168
tertiary C−F branch surrounded by either three fluorinated carbons or two fluorinated carbons
169
plus one carboxyl group. If one surrounding atom is changed to hydrocarbon or oxygen, the
170
defluorination reaction cannot be initiated. Since typical ether compounds synthesized from C3
171
building blocks (e.g., the two shown in Figure 1) do not contain the susceptible C4 branched
172
structure, they are expected to be recalcitrant toward B12-catalyzed defluorination.
173
It is important to emphasize that BDEs of the parent PFASs can only be used to interpret the
174
initiation of defluorination reactions. For example, the experimental data for 1 suggests that,
175
among the sixteen F− released per 1, at least six derived from primary C−F bonds with high
176
BDEs ranging from 481.2 to 492.5 kJ mol−1. In contrast, although the linear 7 contains twelve
177
secondary C−F bonds with BDEs ranging from 451.9 to 458.1 kJ mol−1, no defluorination was 8 ACS Paragon Plus Environment
Page 8 of 17
Page 9 of 17
Environmental Science & Technology Letters
178
observed. These results collectively indicate that B12-catalyzed defluorination reactions are
179
initiated at tertiary C−F bonds with suitable local chemical environments.
180
Defluorination intermediates or end products were not observed by LC−QToF-MS (like those
181
reported by Park et al. on branched PFOS isomers33). One probable reason for the lack of
182
observed products could be that, the fragmentation of PFASs during reaction led to the loss of
183
ionizable groups (e.g., −COO−) that enable MS detection. We emphasize that the actual reaction
184
mechanisms for the multiple step reactions are complicated because the interpretation goes
185
beyond prediction with C−F bond BDEs of the parent structures. For example, the cyclic 3 does
186
not contain any primary C−F bonds, but the defluorination ratio observed was much lower than
187
that for 1, which contains nine primary C−F bonds. Furthermore, if F is replaced by H during
188
defluorination, BDEs of the adjacent C−F bonds in the resulting structures are mostly elevated or
189
unchanged (Figure S3), and this would appear to inhibit subsequent defluorination by the same
190
mechanism. However, based on the unsaturated intermediate structures proposed by Park et al.,33
191
other mechanisms such as HF elimination might be involved in further defluorination. As
192
discussed earlier for compound 2 and HFO-1234yf,47 the presence of C=C bonds could promote
193
defluorination. Clear mechanistic elucidation requires further experiments with more model
194
compounds and theoretical calculations.
195
A protoporphyrin-coordinated complex, Co-PP (Figure 2e),50 exhibited higher initial rate of
196
defluorination than B12 for most PFASs. This trend is apparent for the three examined alcohols
197
(Figure 2f−h). For 1, although the maximum defluorination by Co-PP (an average of thirteen of
198
nineteen C−F bonds cleaved) was lower than by B12, defluorination by Co-PP in the 1st day was
199
higher than by B12 (Figure 2a). For 3, Co-PP was superior to B12 in both initial reaction rate and
200
the maximum defluorination ratio (Figure 2c). Thus, the two Co complexes demonstrate 9 ACS Paragon Plus Environment
Environmental Science & Technology Letters
Page 10 of 17
201
selectivity toward specific PFAS structures. As with B12, structures 4 to 7 (Figure 2d) were not
202
reactive with Co-PP.
203
The difference between Co-PP and B12 might be attributed to two factors. First, the lack of axial
204
benzimidazole lower ligand as in B12 may allow faster electron transfer from TiIII to the CoIII
205
precursor to form the reactive CoI.51 Second, the porphyrin ligand has one more bridging carbon
206
than corrin, and the π-electron resonance is circular. Thus, the N4 ligand cavity size, ring
207
flexibility, and electronic effects in Co-PP are all different from B12,52 thus influencing the
208
defluorination
209
bis(salicylidene)ethylenediamine ligand (Co-salen, Figure 2e), inorganic CoCl2, and Co3O4
210
nanopowder did not show any defluorination activity, suggesting again the critical role of the
211
Co-coordinating ligand in defluorination activity. Systematic investigations are required to probe
212
the effect of ligands. Nevertheless, the above results have clearly shown that even the highly
213
recalcitrant primary sp3 C−F bonds in PFASs could be cleaved by natural and artificial N4-
214
coordinated cobalt species.
215
Although branched structures containing tertiary C−F bonds with low BDEs are subject to Co-
216
catalyzed defluorination, it is worth mentioning that at ambient temperature the branched PFASs
217
would still be relatively recalcitrant in the environment. Results in this letter will be valuable in
218
two aspects of environmental research. First, rational molecular design may be applied to
219
develop more readily degradable PFASs and Co catalysts that are active for the rapid and
220
complete defluorination in both natural and engineered systems. On the other hand, caution
221
should also be taken as branched PFASs may be reactive in cells, tissues, and organs where B12
222
or other catalytic metal species are present.
223
ASSOCIATED CONTENT
activity.
An
N2O2-coordinated
10 ACS Paragon Plus Environment
Co
complex
with
a
Page 11 of 17
Environmental Science & Technology Letters
224
Supporting Information
225 226
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.estlett.xxxxxxx.
227
Additional experimental procedures, tables, and figures
228
Coordinates of optimized geometries of PFASs and their corresponding radicals
229
AUTHOR INFORMATION
230 231 232 233
Corresponding Authors *(J.L.) E-mail:
[email protected];
[email protected]. *(S.V.) E-mail:
[email protected]. *(T.J.S.) E-mail:
[email protected].
234 235
Notes The authors declare no competing financial interest.
236
ACKNOWLEDGEMENTS
237 238 239 240 241
Financial support was provided by the Strategic Environmental Research and Development Program (ER-2424) and the National Science Foundation (CHE-1709719, CHE-1710079). All of the computations were performed using allocated resources at high performance computing facility at Colorado School of Mines. T. Liu and X. Xiao received scholarship support from the China Scholarship Council.
11 ACS Paragon Plus Environment
Environmental Science & Technology Letters
F F
F3 C F F F F CF3 COOH
F3 C
PFMe2OA
F3 C F F CF3 F F SO3 H
COOH
F F F CF3
F F F CF3 F3 C O COOH O F F F F F CF3
HFPO dimer acid (GenX) 242 243 244
SO 3H
di-branched PFOS (3,5-dibrPFOS)
mono-branched PFOS (6-brPFOS) F F
F3 C
F F F F
F F F F F F
F3 C
F FF F
F F
PFECHS
F3 C F F F F F
O
SO3 H F
F F3 C
F F F F F F
F3 C
F F
Page 12 of 17
HFPO trimer acid
*HFPO=Hexafluoropropylene oxide
Figure 1. Examples of branched PFASs detected in the environment. Branched carbons are highlighted in grey.
12 ACS Paragon Plus Environment
Page 13 of 17
245 246 247 248 249
Environmental Science & Technology Letters
Figure 2. Degradation and defluorination for each PFAS with cobalt catalysts shown in (e). Branches that are effective and ineffective in promoting defluorination are highlighted in green and red, respectively. Reaction conditions: PFAS (0.1 mM), Co catalyst (0.25 mM), TiIII citrate (~36 mM), and carbonate buffer (~40 mM) in water; pH 9.0; 70°C.
13 ACS Paragon Plus Environment
Environmental Science & Technology Letters
250 251 252 253
Figure 3. Calculated bond dissociation energies (in kJ mol−1) at B3LYP/6-311+G(2d,2p)/SMD level of theory (BDEs) of C−F bonds in the PFASs shown in Figure 2. The displayed terminal group with two C=O bonds represent charge-delocalized −COO− anion.
14 ACS Paragon Plus Environment
Page 14 of 17
Page 15 of 17
Environmental Science & Technology Letters
254
REFERENCES
255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297
1. Vecitis, C. D.; Park, H.; Cheng, J.; Mader, B. T.; Hoffmann, M. R., Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). Front. Environ. Sci. Eng. 2009, 3, 129-151. 2. Giesy, J. P.; Kannan, K., Peer reviewed: perfluorochemical surfactants in the environment. Environ. Sci. Technol. 2002, 36, 147A-152A. 3. Houde, M.; De Silva, A. O.; Muir, D. C.; Letcher, R. J., Monitoring of perfluorinated compounds in aquatic biota: an updated review: PFCs in aquatic biota. Environ. Sci. Technol. 2011, 45, 7962-7973. 4. Yamashita, N.; Kannan, K.; Taniyasu, S.; Horii, Y.; Petrick, G.; Gamo, T., A global survey of perfluorinated acids in oceans. Mar. Pollut. Bull. 2005, 51, 658-668. 5. Hu, X. C.; Andrews, D. Q.; Lindstrom, A. B.; Bruton, T. A.; Schaider, L. A.; Grandjean, P.; Lohmann, R.; Carignan, C. C.; Blum, A.; Balan, S. A., Detection of poly-and perfluoroalkyl substances (PFASs) in US drinking water linked to industrial sites, military fire training areas, and wastewater treatment plants. Environ. Sci. Technol. Lett. 2016, 3, 344-350. 6. Murakami, M.; Kuroda, K.; Sato, N.; Fukushi, T.; Takizawa, S.; Takada, H., Groundwater pollution by perfluorinated surfactants in Tokyo. Environ. Sci. Technol. 2009, 43, 3480-3486. 7. Hekster, F. M.; Laane, R. W.; de Voogt, P., Environmental and toxicity effects of perfluoroalkylated substances. Rev. Environ. Contam. Toxicol. 2003, 99-121. 8. Lindstrom, A. B.; Strynar, M. J.; Libelo, E. L., Polyfluorinated compounds: past, present, and future. Environ. Sci. Technol. 2011, 45, 7954-7961. 9. Drinking Water Health Advisory for Perfluorooctanoic Acid (PFOA); Office of Water (4304T); Health and Ecological Criteria Division; Document Number 822-R-16-005; U.S. Environmental Protection Agency: Washington, DC, 2016; p 8. 10. Drinking Water Health Advisory for Perfluorooctane Sulfonate (PFOS); Office of Water (4304T); Health and Ecological Criteria Division; Document Number 822-R-16-004; U.S. Environmental Protection Agency: Washington, DC, 2016; p 10. 11. Wang, Z.; Cousins, I. T.; Scheringer, M.; Hungerbühler, K., Fluorinated alternatives to long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their potential precursors. Environ. Int. 2013, 60, 242-248. 12. Sun, M.; Arevalo, E.; Strynar, M.; Lindstrom, A.; Richardson, M.; Kearns, B.; Pickett, A.; Smith, C.; Knappe, D. R., Legacy and emerging perfluoroalkyl substances are important drinking water contaminants in the Cape Fear River Watershed of North Carolina. Environ. Sci. Technol. Lett. 2016, 3, 415-419. 13. Newton, S.; McMahen, R.; Stoeckel, J. A.; Chislock, M.; Lindstrom, A.; Strynar, M., Novel polyfluorinated compounds identified using high resolution mass spectrometry downstream of manufacturing facilities near Decatur, Alabama. Environ. Sci. Technol. 2017, 51, 1544-1552. 14. Rahman, M. F.; Peldszus, S.; Anderson, W. B., Behaviour and fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in drinking water treatment: a review. Water Res. 2014, 50, 318-340. 15. Pan, Y.; Zhang, H.; Cui, Q.; Sheng, N.; Yeung, L. W.; Guo, Y.; Sun, Y.; Dai, J., First report on the occurrence and bioaccumulation of hexafluoropropylene oxide trimer acid: An emerging concern. Environ. Sci. Technol. 2017, 51, 9553-9560. 16. Wang, Z.; Cousins, I. T.; Scheringer, M.; Hungerbuehler, K., Hazard assessment of fluorinated alternatives to long-chain perfluoroalkyl acids (PFAAs) and their precursors: status quo, ongoing challenges and possible solutions. Environ. Int. 2015, 75, 172-179.
15 ACS Paragon Plus Environment
Environmental Science & Technology Letters
298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343
17. Upham, B. L.; Deocampo, N. D.; Wurl, B.; Trosko, J. E., Inhibition of gap junctional intercellular communication by perfluorinated fatty acids is dependent on the chain length of the fluorinated tail. Int. J. Cancer 1998, 78, 491-495. 18. Wang, Y.; Niu, J.; Zhang, L.; Shi, J., Toxicity assessment of perfluorinated carboxylic acids (PFCAs) towards the rotifer Brachionus calyciflorus. Sci. Total Environ. 2014, 491, 266-270. 19. Eriksen, K. T.; Raaschou-Nielsen, O.; Sørensen, M.; Roursgaard, M.; Loft, S.; Møller, P., Genotoxic potential of the perfluorinated chemicals PFOA, PFOS, PFBS, PFNA and PFHxA in human HepG2 cells. Mutat. Res-Gen. Tox. En. 2010, 700, 39-43. 20. Gomis, M. I. From emission sources to human tissues: modelling the exposure to per-and polyfluoroalkyl substances. Ph.D. Thesis, Stockholm University, 2017. 21. Martin, J. W.; Kannan, K.; Berger, U.; Voogt, P. D.; Field, J.; Franklin, J.; Giesy, J. P.; Harner, T.; Muir, D. C.; Scott, B., Peer reviewed: analytical challenges hamper perfluoroalkyl research. Environ. Sci. Technol. 2004, 38, 248A-255A. 22. Reyes, E. A.; Beuterbaugh, A. M.; Smith, A. L., Treatment fluids containing a perfluorinated carboxylic acid for use in subterranean formation operations. US Patent Patent 9,051,510, June 9, 2015. 23. STANDARD 100 by OEKO-TEX - Limit Values and Individual Substances According to Appendices 4 & 5. Edition 02.2017. 24. Ahrens, L.; Plassmann, M.; Xie, Z.; Ebinghaus, R., Determination of polyfluoroalkyl compounds in water and suspended particulate matter in the river Elbe and North Sea, Germany. Front. Environ. Sci. Eng. 2009, 3, 152-170. 25. Howard, P. H.; Muir, D. C., Identifying new persistent and bioaccumulative organics among chemicals in commerce. Environ. Sci. Technol. 2010, 44, 2277-2285. 26. Lescord, G. L.; Kidd, K. A.; De Silva, A. O.; Williamson, M.; Spencer, C.; Wang, X.; Muir, D. C., Perfluorinated and polyfluorinated compounds in lake food webs from the Canadian high arctic. Environ. Sci. Technol. 2015, 49, 2694-2702. 27. Benskin, J. P.; Yeung, L. W.; Yamashita, N.; Taniyasu, S.; Lam, P. K.; Martin, J. W., Perfluorinated acid isomer profiling in water and quantitative assessment of manufacturing source. Environ. Sci. Technol. 2010, 44, 9049-9054. 28. Jin, H.; Zhang, Y.; Jiang, W.; Zhu, L.; Martin, J. W., Isomer–specific distribution of perfluoroalkyl substances in blood. Environ. Sci. Technol. 2016, 50, 7808-7815. 29. Arsenault, G.; Chittim, B.; McAlees, A.; McCrindle, R.; Riddell, N.; Yeo, B., Some issues relating to the use of perfluorooctanesulfonate (PFOS) samples as reference standards. Chemosphere 2008, 70, 616-625. 30. Chu, S.; Letcher, R. J., Linear and branched perfluorooctane sulfonate isomers in technical product and environmental samples by in-port derivatization-gas chromatography-mass spectrometry. Anal. Chem. 2009, 81, 4256-4262. 31. Merino, N.; Qu, Y.; Deeb, R. A.; Hawley, E. L.; Hoffmann, M. R.; Mahendra, S., Degradation and removal methods for perfluoroalkyl and polyfluoroalkyl substances in water. Environ. Eng. Sci. 2016, 33, 615-649. 32. Ochoa-Herrera, V.; Sierra-Alvarez, R.; Somogyi, A.; Jacobsen, N. E.; Wysocki, V. H.; Field, J. A., Reductive defluorination of perfluorooctane sulfonate. Environ. Sci. Technol. 2008, 42, 3260-3264. 33. Park, S.; De Perre, C.; Lee, L. S., Alternate Reductants with VB12 to Transform C8 and C6 Perfluoroalkyl Sulfonates: Limitations and Insights into Isomer-Specific Transformation Rates, Products and Pathways. Environmental Science & Technology 2017, 51, 13869-13877. 34. Phillips, M. M.; Dinglasan-Panlilio, M. J. A.; Mabury, S. A.; Solomon, K. R.; Sibley, P. K., Fluorotelomer acids are more toxic than perfluorinated acids. Environ. Sci. Technol. 2007, 41, 7159-7163.
16 ACS Paragon Plus Environment
Page 16 of 17
Page 17 of 17
344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387
Environmental Science & Technology Letters
35. Liu, J.; Avendaño, S. M., Microbial degradation of polyfluoroalkyl chemicals in the environment: a review. Environ. Int. 2013, 61, 98-114. 36. Zehnder, A.; Wuhrmann, K., Titanium (III) citrate as a nontoxic oxidation-reduction buffering system for the culture of obligate anaerobes. Science 1976, 194, 1165-1166. 37. Grimme, S.; Ehrlich, S.; Goerigk, L., Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 2011, 32, 1456-1465. 38. BecNe, A., Densityϋfunctional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 1993, 98, 5648-5652. 39. Lee, C.; Yang, W.; Parr, R. G., Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B 1988, 37, 785-789. 40. Stephens, P.; Devlin, F.; Chabalowski, C.; Frisch, M. J., Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields. J. Phys. Chem. 1994, 98, 11623-11627. 41. Vosko, S. H.; Wilk, L.; Nusair, M., Accurate spin-dependent electron liquid correlation energies for local spin density calculations: a critical analysis. Can. J. Phys. 1980, 58, 1200-1211. 42. Marenich, A. V.; Cramer, C. J.; Truhlar, D. G., Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions. J. Phys. Chem. B 2009, 113, 6378-6396. 43. Kliegman, S.; McNeill, K., Dechlorination of chloroethylenes by cob(I)alamin and cobalamin model complexes. Dalton Trans. 2008, 4191-4201. 44. Chiu, P.-C.; Reinhard, M., Metallocoenzyme-mediated reductive transformation of carbon tetrachloride in titanium (III) citrate aqueous solution. Environ. Sci. Technol. 1995, 29, 595-603. 45. Payne, K. A.; Quezada, C. P.; Fisher, K.; Dunstan, M. S.; Collins, F. A.; Sjuts, H.; Levy, C.; Hay, S.; Rigby, S. E.; Leys, D., Reductive dehalogenase structure suggests a mechanism for B12-dependent dehalogenation. Nature 2015, 517, 513. 46. Men, Y.; Lee, P. K.; Harding, K. C.; Alvarez-Cohen, L., Characterization of four TCEdechlorinating microbial enrichments grown with different cobalamin stress and methanogenic conditions. Appl. Microbiol. Biotechnol. 2013, 97, 6439-6450. 47. Im, J.; Walshe-Langford, G. E.; Moon, J.-W.; Löffler, F. E., Environmental fate of the next generation refrigerant 2, 3, 3, 3-tetrafluoropropene (HFO-1234yf). Environ. Sci. Technol. 2014, 48, 13181-13187. 48. Baumgartner, R.; McNeill, K., Hydrodefluorination and hydrogenation of fluorobenzene under mild aqueous conditions. Environ. Sci. Technol. 2012, 46, 10199-10205. 49. Yu, Y.-H.; Chiu, P. C., Kinetics and pathway of vinyl fluoride reduction over rhodium. Environ. Sci. Technol. Lett. 2014, 1, 448-452. 50. Yonetani, T.; Yamamoto, H.; Woodrow, G. V., Studies on cobalt myoglobins and hemoglobins I. Preparation and optical properties of myoglobins and hemoglobins containing cobalt proto-, meso-, and deuteroporphyrins and thermodynamic characterization of their reversible oxygenation. J. Biol. Chem. 1974, 249, 682-690. 51. Lexa, D.; Saveant, J. M., The electrochemistry of vitamin B12. Acc. Chem. Res. 1983, 16, 235243. 52. Rovira, C.; Kunc, K.; Hutter, J.; Parrinello, M., Structural and Electronic Properties of Co-corrole, Co-corrin, and Co-porphyrin. Inorg. Chem. 2001, 40, 11-17.
17 ACS Paragon Plus Environment