Photoproduction of hydrogen peroxide in aqueous solution from model compounds for chromophoric dissolved organic matter (CDOM)

Clark, Catherine D.; Bruyn, Warren de; Jones, Joshua G.

doi:10.1016/j.marpolbul.2014.01.001

Cited by 17 publications

(4 citation statements)

References 26 publications

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“…Simple α-dicarbonyls such as MG and glyoxal are known to fluoresce in this region due to their relatively low-energy S 1 ← S 0 ( n , π*) transition. , Therefore, the presence of an α-dicarbonyl functional group can act as a fluorophore in a given molecule. In addition, quinones such as naphthoquinone are also known to have EEM features in the near-UV and are important products in the oxidation of aromatics, as well as being the major constituents of humics in CDOM . At λ ex < 300 nm, nitrogen-containing heterocycles such as tryptophan (which has an indole side chain) and imidazole are major contributors to the fluorescence in the PLOM region. , However, oil-related products including polycyclic aromatic hydrocarbons (PAHs) also have EEM features in the PLOM region .…”

Section: Atmospheric Implicationsmentioning

confidence: 99%

“…71,72 Therefore, the presence of an α-dicarbonyl functional group can act as a fluorophore in a given molecule. In addition, quinones such as naphthoquinone are also known to have EEM features in the near-UV 73 and are important products in the oxidation of aromatics, 35 as well as being the major constituents of humics in CDOM. 74 At λ ex < 300 nm, nitrogen-containing heterocycles such as tryptophan (which has an indole side chain) and imidazole are major contributors to the fluorescence in the PLOM region.…”

Section: Acs Earth Andmentioning

confidence: 99%

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Spectroscopic and Photochemical Properties of Secondary Brown Carbon from Aqueous Reactions of Methylglyoxal

Harrison

Waterson

Bruyn

2020

ACS Earth Space Chem.

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Chromophoric organic compounds in the atmosphere termed brown carbon (BrC) play an important role in tropospheric photochemistry and radiative forcing due to their absorption in the near-UV region of the solar spectrum (300−400 nm). BrC chromophores can form in secondary reactions of carbonyls with ammonium and amine precursors commonly found in aqueous aerosols and cloud water, although there is still uncertainty regarding the contribution of these reactions to atmospheric BrC. Herein, experimental results are presented characterizing the spectroscopic properties of BrC generated from aqueous aerosol/cloud water mimics containing methylglyoxal and ammonium sulfate (MG + AS) or methylamine chloride (MG + MA). Spectroscopic results include mass absorption coefficients, fluorescence quantum yields, and excitation− emission matrix (EEM) spectra, including parallel factor (PARAFAC) analysis. This work also provides a detailed comparison to previous laboratory and field measurements on the classification of aerosols and environmental water with EEM spectroscopy. In addition to spectroscopic characterization, the chemical composition of these samples is investigated using electrospray ionization mass spectrometry and shows the formation of oligomers of methylglyoxal-and nitrogen-containing heterocycles as contributors to absorption in the near-UV consistent with the previous work. The BrC samples were also irradiated using a solar simulator to study the changes in the optical properties and estimate the atmospheric photolytic lifetimes, which have not been previously reported for MG + MA BrC. These results reveal that BrC derived from MG + MA is more stable under solar irradiation than MG + AS BrC with measured atmospheric photolytic half-lives of 39 ± 8 and 12 ± 3 min, respectively.

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Section: Atmospheric Implicationsmentioning

confidence: 99%

Section: Acs Earth Andmentioning

confidence: 99%

Spectroscopic and Photochemical Properties of Secondary Brown Carbon from Aqueous Reactions of Methylglyoxal

Harrison

Waterson

Bruyn

2020

ACS Earth Space Chem.

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“…The photo-chemical production of hydrogen peroxide produced by HA and FA has been reported previously [Aguer et al, 1997, Page et al, 2012, Sharpless et al, 2014. In some cases, the production rate was significantly higher from HA when compared to FA [Clark et al, 2014]. This may result in acceleration of the rate of PE photo-oxidation through photolysis of peroxide into hydroxyl radicals [Litter, 1999] and subsequent abstraction of a proton from the PE backbone followed by the auto-oxidation mechanism previously discussed [Ohtani et al, 1992].…”

Section: Resultsmentioning

confidence: 75%

“…It has been reported in the literature that FA and HA are reactive under photo-oxidative conditions [Aguer et al, 1997, Tchaikovskaya et al, 2005, Page et al, 2012, Sharpless et al, 2014, Clark et al, 2014.…”

Section: Resultsmentioning

confidence: 98%

Understanding and predicting environmental effects on degradation of oxo-degradable polyethylene blown films

Gauthier¹

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Polyethylene (PE) based films are commonly used in agriculture for different applications such as mulching, walk-in tunnel and mini greenhouse. In the case of mini greenhouse, the thin film creates a confined environment providing favourable conditions for crop growth, such as increased temperature and moisture retention, hence reducing the need for irrigation and agrochemical treatments. However, in this specific application, it is necessary to control the rate of degradation of the film above ground to enable healthy crop growth. Several studies have investigated the photo-and/or thermo-oxidation of PE in sunlight and when buried in soil or compost. However the degradation rate is not well controlled and the degradation mechanisms are not fully understood. The service lifetime of polymer films is controlled by the chemical reactions leading to chain scission and mediating environmental factors. For application in agricultural cropping films, a controlled accelerated degradation is required. The rate of PE film degradation can be influenced by its intrinsic properties (such as polymer grade, concentration and/or type of pro-degradants) but also by environmental factors, such as UV dose, temperature and humidity. However, in practice, these are not the only factors controlling the polymer lifetime, with poor translation from model (laboratory based) accelerated ageing studies to in-field application. This creates a challenge in accurately predicting the useful iii rate of photo-oxidation. Overall, additional environmental factors to solar dose and temperature were influencing the rate of PE photo-degradation. The key factors were found to be the presence of condensed water and soil type. For the latter factor, the specific soil properties of importance with respect to film degradation appeared to be associated with organic matter, although the impact of soil on PE photo-oxidation was found to be complex and likely dependent at least in part v on soil components that varied between different soil types, consequently influencing their photo-chemistry. This knowledge could assist in designing a modelling tool to recommend the appropriated time-controlled PE film suitable for a specific crop cycles at specific sites across Australia. These findings could also be transferred to other degradable PE film applications, such as mulch films, plastic bags and other packaging products. vi Declaration by author This thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis. I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, financial support and any other original research work used or reported in my thesis. The content of my thesis is the result of work I have...

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Effect of soil environment on the photo‐degradation of polyethylene films

Gauthier

Nikolić

Truss

et al. 2015

J of Applied Polymer Sci

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Outdoor weathering field trials performed with oxo-degradable polyethylene (PE) thin films were conducted across temperate, grassland, and subtropical sites around Australia. It was found that a site factor, that was apparently independent of total solar dose and temperature, significantly impacted the rate and extent of photo-oxidation. Controlled laboratory-based accelerated aging trials of both PE film with no prodegradant and oxo-degradable PE films (containing iron stearate) revealed that the rate and extent of PE photo-oxidation did not correlate with temperature under the film or UV exposure, but was soil dependent. Under accelerated photo-oxidative conditions, the time to reach embrittlement for a PE film aged over the soil from the temperate site (OM 8.4) was half (24.5 days) the time taken when aged over air (48 days). Further investigation revealed that humic acids and fulvic acids within soil organic matter may contribute to an increased rate of PE photo-oxidation, possibly through the formation of volatile reactive oxygen species that may form under photo-oxidative conditions. The presence of water also had a significant impact on the rate of photo-oxidation. Overall, the impact of soil on PE photo-oxidation was found to be complex and likely dependent at least in part on soil components that varied between different soil types, consequently influencing their photo-chemistry. V C 2015 Wiley Periodicals, Inc. J.Appl. Polym. Sci. 2015, 132, 42558.

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Photoproduction of hydrogen peroxide in aqueous solution from model compounds for chromophoric dissolved organic matter (CDOM)

Cited by 17 publications

References 26 publications

Spectroscopic and Photochemical Properties of Secondary Brown Carbon from Aqueous Reactions of Methylglyoxal

Spectroscopic and Photochemical Properties of Secondary Brown Carbon from Aqueous Reactions of Methylglyoxal

Understanding and predicting environmental effects on degradation of oxo-degradable polyethylene blown films

Effect of soil environment on the photo‐degradation of polyethylene films

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