CHF₃ (HFC-23) and CF₃CHO Quantum Yields in the Pulsed Laser Photolysis of CF₃CHO at 248, 266, 281, and 308 nm

ACS Earth and Space Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Фев. 27, 2025

Ultraviolet (UV) photolysis of trifluoroacetaldehyde (CF3CHO), an atmospheric degradation product anthropogenically emitted compounds, is a potential source fluoroform (CHF3, HFC-23), which potent greenhouse gas. In this study, CF3CHO quantum yields, ϕCF3CHO(λ, P), and CHF3 yields were measured following the pulsed laser at 248, 266, 281, 308 nm total pressures between 100 678 Torr (N2/NO bath gas mixtures). Loss was using Fourier transform infrared spectroscopy (FTIR), formation by FTIR (248, 281 nm) off-line chromatography–mass spectrometry (GC/MS) nm). ϕCF3CHO(248 nm, 650–678 Torr) ϕCF3CHO(266 650 to be 1.03 ± 0.06 0.94 0.06, respectively, i.e., near unity, CBrF2CBrF2 (Halon-2402) CF3I as actinometry references, respectively. The molar 248 266 0.348 0.02 0.438 0.015, for found pressure-dependent over (N2/NO) pressure range. A Stern–Volmer analysis yield results yielded kQ/kD values (3.25 0.20) × 10–20 cm3 molecule–1 (1.91 0.02) 10–19 ϕCF3CHO(281 = 0.54 (308 0.204 0.028. obtained showed weak decrease with increasing 0.105 0.002 (1.71 0.70) 10–3 Torr, All quoted measurement uncertainties are 2σ standard deviation. An evaluation photochemical hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), hydrofluoroolefins (HFOs), hydrochlorofluoroolefins (HCFOs) that observed in present-day atmosphere presented implications discussed.

Язык: Английский

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The Global Threat from the Irreversible Accumulation of Trifluoroacetic Acid (TFA)

Environmental Science & Technology, Год журнала: 2024, Номер 58(45), С. 19925 - 19935

Опубликована: Окт. 30, 2024

Trifluoroacetic acid (TFA) is a persistent and mobile substance that has been increasing in concentration within diverse environmental media, including rain, soils, human serum, plants, plant-based foods, drinking water. Currently, TFA concentrations are orders of magnitude higher than those other per- polyfluoroalkyl substances (PFAS). This accumulation due to many PFAS having as transformation product, several fluorinated gases (F-gases), pesticides, pharmaceuticals, industrial chemicals, addition direct release industrially produced TFA. Due TFA's extreme persistence ongoing emissions, irreversibly. What remains less clear the thresholds where irreversible effects on local or global scales occur. There indications from mammalian toxicity studies toxic reproduction it exhibits liver toxicity. Ecotoxicity data scarce, with most being for aquatic systems; fewer available terrestrial bioaccumulates readily. Collectively, these trends imply meets criteria planetary boundary threat novel entities because planetary-scale exposure, potential disruptive impacts vital earth system processes could The rational response this instigate binding actions reduce emissions its precursors.

Язык: Английский

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Reaction mechanism and product characteristics of two mixtures with HFO-1225zc

Chemical Engineering Science, Год журнала: 2025, Номер unknown, С. 121258 - 121258

Опубликована: Янв. 1, 2025

Язык: Английский

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Ai-Driven Cooling Technologies for High-Performance Data Centers: State-of-The-Art Review and Future Directions

Опубликована: Янв. 1, 2025

Язык: Английский

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Environmental consequences of interacting effects of changes in stratospheric ozone, ultraviolet radiation, and climate: UNEP Environmental Effects Assessment Panel, Update 2024

Photochemical & Photobiological Sciences, Год журнала: 2025, Номер unknown

Опубликована: Март 17, 2025

Abstract This Assessment Update by the Environmental Effects Panel (EEAP) of United Nations Environment Programme (UNEP) addresses interacting effects changes in stratospheric ozone, solar ultraviolet (UV) radiation, and climate on environment human health. These include new modelling studies that confirm benefits Montreal Protocol protecting ozone layer its role maintaining a stable climate, both at low high latitudes. We also provide an update projected levels UV-radiation during twenty-first century. Potential environmental consequences intervention scenarios are briefly discussed, illustrating large uncertainties of, for example, Stratospheric Aerosol Injection (SAI). Modelling predict that, although SAI would cool Earth’s surface, other factors be affected, including depletion precipitation patterns. The contribution to global warming replacements ozone-depleting substances (ODS) assessed. With respect breakdown products chemicals under purview Protocol, risks ecosystem health from formation trifluoroacetic acid (TFA) as degradation product ODS currently de minimis . change continue have complex interactive due largely activities. UV-radiation, weathering factors, microbial action contribute significantly plastic waste environment, affecting transport, fate, toxicity plastics terrestrial aquatic ecosystems, atmosphere. Sustainability demands drive industry innovations mitigate use disposal plastic-containing materials. Terrestrial ecosystems alpine polar environments increasingly being exposed enhanced earlier seasonal snow ice melt because extended periods depletion. Solar contributes decomposition dead plant material, which affects nutrient cycling, carbon storage, emission greenhouse gases, soil fertility. In loss cover is increasing area oceans with possible negative phytoplankton productivity. However, Arctic Ocean circulation suggests circulating progressively deeper ocean layers less UV irradiation. Human modified behaviour patterns, resulting exposure harmful or beneficial depending conditions skin type. For incidence melanoma has been associated increased air temperature, time spent outdoors thus UV-radiation. Overall, implementation Amendments mitigated deleterious

Язык: Английский

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Magnetocaloric effect and critical behavior of Nd1-3xBaxCaxSrxMnO₃ (0.066 ≤ x ≤ 0.11) manganites: optimization of doping for enhanced refrigerant performance

Applied Physics A, Год журнала: 2025, Номер 131(4)

Опубликована: Март 21, 2025

Язык: Английский

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Reply to the ‘Comment on “Assessing the atmospheric fate of trifluoroacetaldehyde (CF₃CHO) and its potential as a new source of fluoroform (HFC-23) using the AtChem2 box model”’ by O. J. Nielsen, M. P. Sulbaek Andersen and J. Franklin, Environ. Sci.: Atmos., 2025, 5, DOI: 10.1039/D4EA00123K

Environmental Science Atmospheres, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

In Pérez-Peña et al. (DOI: https://doi.org/10.1039/d3ea00120b), we used a suite of box model simulations to determine how trifluoroacetaldehyde (CF 3 CHO) produced from HFO-1234ze is lost in the atmosphere and much fluoroform (CHF or HFC-23) could potentially be as result. For first time any modelling study, our included both minor CF CHO photolytic loss channel leading CHF production physical removal via wet dry deposition. their comment, Sulbaek Andersen, Nielsen, Franklin query assumptions simulate these processes. Here, show that importance pathway remains matter community debate results are relatively insensitive underlying simulation We reiterate need for measurements properties reduce uncertainties processes pave way more sophisticated models.

Язык: Английский

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The global threat from the irreversible accumulation of trifluoroacetic acid (TFA)

Опубликована: Июнь 19, 2024

Trifluoroacetic acid (TFA) is a hydrophilic, non-degradable substance that has been increasing in concentrations within diverse environmental media, including rain, soils, human serum, plants, plant-based foods, and drinking water. Currently, TFA are orders of magnitude higher than those other per- polyfluoroalkyl substances (PFAS). This accumulation due to many PFAS have as transformation byproduct, several fluorinated gases (F-gases), high-volume pesticides, pharmaceuticals industrial chemicals, addition direct release. Due TFA’s extreme persistence mobility, these irreversibly. What remains less clear the thresholds where irreversible effects on local or global scales occur. There indications from mammalian toxicity studies toxic reproduction it exhibits liver toxicity. Ecotoxicity data scarce, with most for aquatic systems; fewer available terrestrial bioaccumulates readily. Collectively, trends imply meets criteria planetary boundary threat novel entities because planetary-scale exposure, potential, disruptive impacts vital earth system processes could The rational response this instigate binding actions reduce emissions its precursors.

Язык: Английский

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Electronic Spectroscopy of the Halogenated Criegee Intermediate, ClCHOO: Experiment and Theory

The Journal of Physical Chemistry A, Год журнала: 2024, Номер unknown

Опубликована: Дек. 12, 2024

A chlorine-substituted Criegee intermediate, ClCHOO, is photolytically generated using a diiodo precursor, detected by VUV photoionization at 118 nm, and spectroscopically characterized via ultraviolet-visible (UV-vis)-induced depletion of

Язык: Английский

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