1. Coagulant-Enhanced Sorption of Perfluoroalkyl Substances
Yousof Aly1, Daniel P. McInnis1, Chen Liu2, Bonnie A. Lyon2, Kurt D. Pennell2, William A. Arnold3, Matt F. Simcik1
1University of Minnesota – School of Public Health; 2Tufts University – Department of Civil and Environmental Engineering; 3University of Minnesota – Department of Civil, Environmental, and Geo- Engineering
1. BACKGROUND 4. RESULTS
• Simple coagulants alum [Al2(SO4)3] and ferric chloride
[FeCl3∙6H2O] could remove PFOA, PFOS from solution
• Removal efficiencies ranged from 0-35% depending on
solution pH and coagulant dose
3. MATERIALS AND METHODS
polydiallyldimethyl
ammonium chloride
(polyDADMAC)
epichlorohydrin-
dimethylamine
(polyamine) 5. CONCLUSIONS
• Greater sorption of PFASs in the presence of cationic coagulant
• polyDADMAC significantly better than polyamine and poly aluminum chloride
• % increase in Kd for Poly-DADMAC = 66-378%
• % PFAS removal with addition of sorption enhancer = 0-25%
Perfluoroalkyl substances (PFASs)
PFBS perfluorobutane sulfonate
PFHxS perfluorohexane sulfonate
PFOS perfluorooctane sulfonate
PFHpA perfluoroheptanoic acid
PFOA perfluorooctanoic acid
PFNA perfluorononanoic acid
+
6. FUTURE DIRECTIONS
•Sorption of PFAS on contaminated soil (Tinker Air Force Base, Oklahoma, USA)
•Controlled release of coagulant
•Effectiveness of coagulants in the presence of co-contaminants (diesel fuel)
•One-dimensional column studies and two-dimensional aquifer cells
AlnCl(3n-m)(OH)m
Johnson, R.L., Anschutz, A.J., Smolen, J.M., Simcik, M.F., Penn, R.L., 2007. The
adsorption of perfluorooctanesulfonate onto sand, clay, and iron oxide surfaces. J.
Chem. Eng. Data 52, 1165-1170.
Xiao, F., Simcik, M.F., Gulliver, J.S., 2013. Mechanisms for removal of perfluorooctane
sulfonate (PFOS) and perfluorooctanoate (PFOA) from drinking water by conventional
and enhanced coagulation. Water Res. 47, 49-56.
This material is based upon work supported by the U.S. Army Corps of Engineers,
Humphreys Engineer Center Support Activity under Contract No. W912HQ-14-C-0042.
polyaluminum
chloride
2. HYPOTHESIS AND PREDICTIONS
• Since PFAS exhibit negative charges in water, we hypothesize that cationic coagulants will enhance their sorption to
Ottawa sand
• Furthermore, Ottawa sand is less sorptive than natural soils, so we predict further enhanced sorption of PFAS on
aquifer materials
% increase in Kd
over control
polyDADMAC polyamine polyaluminum
chloride
PFBS 95% 12% -13%
PFHxS 73% 31% 52%
PFOS 105% 43% 7%
PFHpA 66% -29% -11%
PFOA 378% 100% 18%
PFNA 124% 65% 24%
7. REFERENCES AND ACKNOWLEDGEMENTS
• 25 g Ottawa Sand (40-60 mesh), 10 mL water, sorption enhancer (100 mg/L), and PFASs added simultaneously
• Batches placed on wrist shaker for 24 hours to reach equilibrium
• Sorption enhancer dose selected based on monolayer coverage determined from sorption enhancer isotherms (shown
above)
Xiao et al. (2013)Johnson et al. (2007)
• Sorption of PFOS to Ottawa sand higher than would be
predicted from organic carbon content alone
• 74 – 99% of PFOS could be adsorbed onto solid surfaces
in a groundwater system
Sorption Enhancers
→
Analysis:
• PFASs analyzed by LC/MS following method described by Xiao et al. 2013.
• Labeled isotopes used as internal standards for quantification.
PFASAdsorbed(ng/gsand)
Equilibrium PFAS Concentration (ng/mL)
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 20 40 60 80 100
PFBS
control
polyaluminum chloride
polyamine
polyDADMAC
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0 20 40 60 80 100
PFHxS
-0.5
1.5
3.5
5.5
7.5
9.5
11.5
0 20 40 60 80 100
PFOS
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0 20 40 60 80 100
PFHpA
-0.5
0.5
1.5
2.5
3.5
4.5
5.5
6.5
7.5
0 20 40 60 80 100
PFOA
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 20 40 60 80 100
PFNA
0
0.2
0.4
0.6
0.8
1
1.2
0.0 50.0 100.0 150.0
*polyaluminum chloride
equilibrium enhancer concentration mg/L
* concentration in mg Al/L
mgenhancersorbed/gsand
0.00
0.01
0.02
0.04
0 100 200 300
polyamine
0.00
0.01
0.02
0.03
0.00 100.00 200.00 300.00
polyDADMAC