Theoretical study of the ammonium perfluorooctanoate/water system

Duvoisin, Sérgio; Kuhnen, Carlos Alberto; Ouriques, Gerson Renzetti

doi:10.1016/s0166-1280(02)00423-2

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…54 At the air/water interface, each PFO headgroup occupies 41-42 Å 2 in a monolayer. [56][57][58][59] The corresponding number for decyl sulfate is 55 Å 2 . 60 With those numbers, our plateau region in Figure 2 corresponds, approximately and on average, to monolayers (∼0.8 monolayer for pure NaPFO and ∼0.9 monolayer for pure SDeS).…”

Section: Resultsmentioning

confidence: 99%

Mixed Adsorption of Fluorinated and Hydrogenated Surfactants

2006

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The adsorption isotherms of sodium perfluorooctanoate and sodium decyl sulfate and their 1:1 mixture on gamma-alumina are recorded by depletion-type experiments with (1)H and (19)F NMR spectroscopy as the detection tool. The isotherms of the different surfactant species, obtained with and without added salt, closely resemble each other. Salt addition changes the isotherms from stepwise to the familiar S-shaped. After having reached saturation, a further increase of surfactant concentration in the mixed system leads to decyl sulfate desorption and increased perfluorooctanoate adsorption. The (19)F chemical shift of adsorbed perfluorooctanoate suggests that, for saturated surfaces, the two sorts of adsorbed surfactants form molecularly mixed surface aggregates.

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Section: Resultsmentioning

confidence: 99%

Mixed Adsorption of Fluorinated and Hydrogenated Surfactants

2006

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“…An “ab initio” quantum computational study of PFOA/H 2 O system reported that on average eight water molecules can be accommodated near the polar headgroup of the PFO – ion . The reported hydration numbers for NH 4 + ion vary widely from 4 to 11. , On the basis of the reported hydration numbers for NH 4 + ion and PFO – ion, we fixed N H = 12.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea

et al. 2021

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The self-assembly of surfactants in aqueous solution can be modulated by the presence of additives including urea, which is a well-known protein denaturant and also present in physiological fluids and agricultural runoff. This study addresses the effects of urea on the structure of micelles formed in water by the fluorinated surfactant perfluoro-n-octanoic acid ammonium salt (PFOA). Analysis of small-angle neutron scattering (SANS) experiments and atomistic molecular dynamics (MD) simulations provide consensus strong evidence for the direct mechanism of urea action on micellization: urea helps solvate the hydrophobic micelle core by localizing at the surface of the core in the place of some water molecules. Consequently, urea decreases electrostatic interactions at the micelle shell, changes the micelle shape from prolate ellipsoid to sphere, and decreases the number of surfactant molecules associating in a micelle. These findings inform the interactions and behavior of surface active per-and polyfluoroalkyl substances (PFAS) released in the aqueous environment and biota.

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“…Considering the volume contributions from one CF 2 group, surfactant headgroups, counterions, fraction of PEO homopolymer in the shell, and associated water molecules, the micelle shell volume can be written as where V CF 2 , V COO – , V NH 4 + , V D 2 O , and V EO are the volumes of the CF 2 group, PFOA headgroup, counterion NH 4 + , D 2 O molecule, and ethylene oxide monomer, respectively, α = Z / N agg is the fractional charge on a micelle ( Z is the charge on a micelle), N H is the hydration number of a surfactant molecule, n EO is the number of EO segments in the micelle shell, and N H,EO are the water molecules (hydration number) per EO segment in the micelle shell. On the basis of the reported hydration numbers for the NH 4 + ion , and PFO – ion, we fixed N H = 12. In addition, we fixed N H,EO = 4.6 based on our SANS results of 3% PEO 10000 in D 2 O considering the correlation length model.…”

Section: Methodsmentioning

confidence: 99%

Binding of Perfluorooctanoate to Poly(ethylene oxide)

et al. 2022

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To inform the design of polymer-based adsorbent materials for sequestration of per- and polyfluoroalkyl substances (PFAS) from aqueous solution, we report here on the critical aggregation concentration (CAC), shape, size, composition, and interactions of assemblies formed in water between perfluorooctanoic acid ammonium salt (PFOA) and the nonionic polymer poly(ethylene oxide) (PEO), obtained from complementary experiments (conductivity, surface tension, pyrene fluorescence, viscosity, and small-angle neutron scattering (SANS)) and atomistic molecular dynamics (MD) simulations. PEO–PFAS binding commences at concentrations lower than the PFOA critical micelle concentration (CMC) and is driven by PEO localizing on the micelle surface and shielding the fluorocarbon parts of PFOA from contact with water. PFOA + PEO mixed micelles have a 10% higher association number and are 40% more elongated compared to polymer-free PFOA micelles. This is the first investigation on the structure of polymer + fluorocarbon surfactant mixed micelles and contributes fundamental insights into the association of water-soluble polymers with PFAS surfactants.

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Theoretical study of the ammonium perfluorooctanoate/water system

Cited by 5 publications

References 14 publications

Mixed Adsorption of Fluorinated and Hydrogenated Surfactants

Mixed Adsorption of Fluorinated and Hydrogenated Surfactants

Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea

Binding of Perfluorooctanoate to Poly(ethylene oxide)

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