Modeling and Experimental Study on the Thermal Decomposition of Perfluorooctanesulfonic Acid (Pfos) in an Α-Alumina Reactor

Weber, Nathan H.; Delva, Cameron; Grimison, Charles; Stockenhuber, Sebastian P.; Lucas, John; Mackie, John C.; Stockenhuber, Michael; Kennedy, Eric M.

doi:10.2139/ssrn.3985148

Cited by 2 publications

(14 citation statements)

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“…The quantitative and qualitative analyses of the products have not changed from our previous PFOS studies. 21,22 Computational Methodology. The quantum chemical analysis of the reactions between H 2 O (g) and the products from the thermal decomposition of PFOS were studied using Gaussian 09.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Reaction between CF 2 and OH. In our pyrolysis model, 22 we included the reaction between these two radicals to form COF 2 + H. This reaction has been studied by Srinivasan et al 29 who considered the reaction to pass through an intermediate, CF 2 OH, leading to products COF 2 + H. While this reaction is exothermic by 232 kJ mol −1 , there is another route which is even more exothermic at −294 kJ mol −1 . This is reaction 3 which is postulated to take place via…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Based on the kinetic model we developed for PFAS pyrolysis, 22 we expanded the model to include the reaction of water vapor with key fluorochemical radical species, CF 2 + H 2 O, CF 2 + OH, CF 3 + H 2 O, and H 2 O + F, as described in the theoretical section and discussed previously. Some of the rate constants included in the model and involving H 2 O, OH, and CO are extracted from the GRI-Mech 3.0, such as CO + OH and H + OH.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Furthermore, C 8 F 16 O was also found to fission into FCO and C 7 F 15, which will also rapidly decompose into CF 2 radicals. 22 This indicates that the pyrolysis of PFOS will form large amounts of CF 2 radicals at elevated temperatures. An additional finding from both our previous studies was that the α-alumina reactor surface increased the initial rates of the thermal decomposition of PFOS.…”

Section: ■ Introductionmentioning

confidence: 99%

“…An additional finding from both our previous studies was that the α-alumina reactor surface increased the initial rates of the thermal decomposition of PFOS. 21,22 Complete destruction of PFOS involves the formation of HF. In the development of such a process, one of the key factors to consider is that PFOS has only one hydrogen atom present in its structure.…”

Section: ■ Introductionmentioning

confidence: 99%

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Thermal Decomposition of Perfluorooctanesulfonic Acid (PFOS) in the Presence of Water Vapor

Weber

Delva

Stockenhuber

et al. 2022

Ind. Eng. Chem. Res.

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The thermal decomposition of perfluorooctanesulfonic acid (PFOS) was studied in an α-alumina reactor between 500 and 1000 °C using helium as a carrier gas. In addition to He carrier gas and between 150 and 300 ppm of PFOS, the effect of water vapor (H2O(g)) at two different concentrations (1700 and 10,000 ppm) on the reaction was examined. The main products, at both 1700 and 10,000 ppm of H2O(g), were HF, C2F4, CO, and SO2. Moreover, as the reaction temperature increased, an increase in the concentration of HF and CO was observed, concomitant with a decrease in the fluorocarbon concentration. Additionally, the α-alumina reactor was observed to have reduced surface activity in the presence of water vapor. Quantum chemical calculations, performed at the G4MP2 level of theory combined with a chemical kinetic model, were used to understand the influence that water vapor and OH radicals have on the CF2 and CF3 radicals that are present. It was found that at temperatures above 850 °C in 10,000 ppm of water vapor, there is a substantial decrease in the fluorocarbon concentration.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Thermal Decomposition of Perfluorooctanesulfonic Acid (PFOS) in the Presence of Water Vapor

Weber

Delva

Stockenhuber

et al. 2022

Ind. Eng. Chem. Res.

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Thermal Mineralization of Perfluorooctanesulfonic Acid (PFOS) to HF, CO₂, and SO₂

Weber

Delva

Stockenhuber

et al. 2023

Ind. Eng. Chem. Res.

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Utilizing air (O2) as the bath gas at reaction temperatures between 500 and 1000 °C, the thermal decomposition of perfluorooctanesulfonic acid (PFOS) in an α-alumina reactor was studied. It was found that in an air bath gas (and in the absence of water vapor), COF2 and trace amounts of C2F4 were detected. Quantum chemical calculations at the G4MP2 level of theory confirmed that CF2 radicals can react with O2 to form COF2 and an O (3P) atom. The inclusion of 2000 or 20 000 ppmv of water vapor (H2O(g)) to the air bath gas proved to be the key step to mineralizing all PFOS into hydrogen fluoride (HF), CO2, and SO2. At temperatures above 850 °C (0.95–0.84 s residence time), a feed of 20 000 ppmv of H2O(g) in air was observed to produce a product stream in which no gaseous fluorocarbon products were detected, with only HF, SO2, and CO2 being produced. A sulfur balance confirmed that 100 ± 5% of all the S in PFOS had converted into SO2 with a chemical kinetic model predicting in excess of 99.99999% destruction removal efficiency of PFOS at temperatures above 700 °C. Furthermore, from an elementary balance of F and C atoms, it was determined that at 1000 °C, approximately 99 ± 5% of F atoms present in PFOS have been converted into HF, and approximately 100 ± 5% of C atoms had been converted into CO2. A chemical kinetic model was developed to understand the importance of both O2 and water vapor in the overall thermal decomposition of PFOS, leading to complete mineralization. In the presence of both O2 and H2O(g), it was found that relatively high concentrations of OH radicals were produced, with significant contribution to OH formation attributed to the well-known chain branching reaction O(3P) + H2O → OH + OH.

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Modeling and Experimental Study on the Thermal Decomposition of Perfluorooctanesulfonic Acid (Pfos) in an Α-Alumina Reactor

Cited by 2 publications

References 1 publication

Thermal Decomposition of Perfluorooctanesulfonic Acid (PFOS) in the Presence of Water Vapor

Thermal Decomposition of Perfluorooctanesulfonic Acid (PFOS) in the Presence of Water Vapor

Thermal Mineralization of Perfluorooctanesulfonic Acid (PFOS) to HF, CO₂, and SO₂

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Modeling and Experimental Study on the Thermal Decomposition of Perfluorooctanesulfonic Acid (Pfos) in an Α-Alumina Reactor

Cited by 2 publications

References 1 publication

Thermal Decomposition of Perfluorooctanesulfonic Acid (PFOS) in the Presence of Water Vapor

Thermal Decomposition of Perfluorooctanesulfonic Acid (PFOS) in the Presence of Water Vapor

Thermal Mineralization of Perfluorooctanesulfonic Acid (PFOS) to HF, CO2, and SO2

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Thermal Mineralization of Perfluorooctanesulfonic Acid (PFOS) to HF, CO₂, and SO₂