TY - JOUR
T1 - Sonochemical degradation of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in groundwater
T2 - Kinetic effects of matrix inorganics
AU - Cheng, Jie
AU - Vecitis, Chad D.
AU - Park, Hyunwoong
AU - Mader, Brian T.
AU - Hoffmann, Michael R.
PY - 2010/1/1
Y1 - 2010/1/1
N2 - Ultrasonic irradiation has been shown to effectively degrade perfluorinated chemicals (PFCs)such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in aqueous solution. Reduced PFC sonochemical degradation rates in organic-rich groundwater taken from beneath a landfill, however, testify to the negative kinetic effects of the organic groundwater constituents. In this study, the PFOX (X = S or A) sonochemical degradation rates in a groundwater sample with organic concentrations about 10 times lower than those in the groundwater taken from beneath a landfill are found to be 29.7% and 20.5% lower, respectively, than the rates in Milli-Q water, suggesting that inorganic groundwater constituents also negatively affect PFC sonochemical kinetics. To determine the source of the groundwater matrix effects, we evaluate the effects of various inorganic species on PFOX sonochemical kinetics. Anions over the range of 1-10 mM show Hofmeister effects on the sonochemical degradation rates of PFOX, kClO4--PFOX > kNO3--PFOX ∼ kCl--PFOX ≥ kMQ-PFOX > kHCO3--PFOX ∼ kSO42--PFOX. In contrast, common cations at 5 mM have negligible effects. Initial solution pH enhances the degradation rates of PFOX at 3, but has negligible effects over the range of 4 to 11. The observed inorganic effects on sonochemical kinetics are hypothesized to be due to ions' partitioning to and interaction with the bubble - water interface. Finally, it is shown that the rate reduction in the groundwater in this study is primarily due to the presence of bicarbonate and thus can be fully rectified by pH adjustment prior to sonolysis.
AB - Ultrasonic irradiation has been shown to effectively degrade perfluorinated chemicals (PFCs)such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in aqueous solution. Reduced PFC sonochemical degradation rates in organic-rich groundwater taken from beneath a landfill, however, testify to the negative kinetic effects of the organic groundwater constituents. In this study, the PFOX (X = S or A) sonochemical degradation rates in a groundwater sample with organic concentrations about 10 times lower than those in the groundwater taken from beneath a landfill are found to be 29.7% and 20.5% lower, respectively, than the rates in Milli-Q water, suggesting that inorganic groundwater constituents also negatively affect PFC sonochemical kinetics. To determine the source of the groundwater matrix effects, we evaluate the effects of various inorganic species on PFOX sonochemical kinetics. Anions over the range of 1-10 mM show Hofmeister effects on the sonochemical degradation rates of PFOX, kClO4--PFOX > kNO3--PFOX ∼ kCl--PFOX ≥ kMQ-PFOX > kHCO3--PFOX ∼ kSO42--PFOX. In contrast, common cations at 5 mM have negligible effects. Initial solution pH enhances the degradation rates of PFOX at 3, but has negligible effects over the range of 4 to 11. The observed inorganic effects on sonochemical kinetics are hypothesized to be due to ions' partitioning to and interaction with the bubble - water interface. Finally, it is shown that the rate reduction in the groundwater in this study is primarily due to the presence of bicarbonate and thus can be fully rectified by pH adjustment prior to sonolysis.
UR - http://www.scopus.com/inward/record.url?scp=75349094717&partnerID=8YFLogxK
U2 - 10.1021/es902651g
DO - 10.1021/es902651g
M3 - Article
C2 - 19950930
AN - SCOPUS:75349094717
SN - 0013-936X
VL - 44
SP - 445
EP - 450
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 1
ER -