C 1s K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy for characterizing functional group chemistry of black carbon

Heymann, Karen; Lehmann, Johannes; Solomon, Daniel; Schmidt, Michael W. I.; Regier, T. Z.

doi:10.1016/j.orggeochem.2011.06.021

Cited by 108 publications

(80 citation statements)

References 59 publications

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“…We did not find N 2 O emitted under abiotic conditions in the two soils most susceptible to chemodenitrification used in this study (Elba and Guarapuava), which implies that the N 2 O emitted from the soils was entirely produced through biotically mediated mechanisms. It also shows that biochar did in our study not abiotically induce N 2 O formation in soil through previously proposed catalytic reactions with hydroquinones 30,31 , metal ions or radicals 19,32 , which are abundant in biochars 31,33 . Previous studies on N 2 O emissions and biochar are limited to one or two soil types 3,4,7,9,10,12,13,34,35 .…”

Section: Discussionsupporting

confidence: 68%

Use of biochar to enhance constructed wetland performance in wastewater reclamation

Gupta

Ann

Lee

2016

Environmental Engineering Research

125

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Agricultural soils represent the main source of anthropogenic N 2 O emissions. Recently, interactions of black carbon with the nitrogen cycle have been recognized and the use of biochar is being investigated as a means to reduce N 2 O emissions. However, the mechanisms of reduction remain unclear. Here we demonstrate the significant impact of biochar on denitrification, with a consistent decrease in N 2 O emissions by 10-90% in 14 different agricultural soils. Using the 15 N gas-flux method we observed a consistent reduction of the N 2 O/(N 2 1 N 2 O) ratio, which demonstrates that biochar facilitates the last step of denitrification. Biochar acid buffer capacity was identified as an important aspect for mitigation that was not primarily caused by a pH shift in soil. We propose the function of biochar as an ''electron shuttle'' that facilitates the transfer of electrons to soil denitrifying microorganisms, which together with its liming effect would promote the reduction of N 2 O to N 2 .

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Section: Discussionsupporting

confidence: 68%

Use of biochar to enhance constructed wetland performance in wastewater reclamation

Gupta

Ann

Lee

2016

Environmental Engineering Research

125

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“…Whereas the rim displays the dominant feature at ∼285.1 eV of aromatic C, this band is less pronounced in the core and instead shows two smaller peaks ∼1 eV apart at ∼285.1 and ∼286.5 eV (Table S2). The interior has a distinct extra shoulder at ∼283 eV, which can be explained by C=O bonding environments (40). The second feature at ∼286.5 eV can as well be attributed to functional groups involving oxygen bonding, i.e., aldehyde (286.3 eV) or ketone (286.6-286.8 eV) as well as nitrile C≡N triple bonding (Table S2) (9).…”

Section: The Twomentioning

confidence: 98%

Fluid-induced organic synthesis in the solar nebula recorded in extraterrestrial dust from meteorites

Vollmer

Kepaptsoglou

Leitner³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Isotopically anomalous carbonaceous grains in extraterrestrial samples represent the most pristine organics that were delivered to the early Earth. Here we report on gentle aberration-corrected scanning transmission electron microscopy investigations of eight 15 N-rich or D-rich organic grains within two carbonaceous Renazzo-type (CR) chondrites and two interplanetary dust particles (IDPs) originating from comets. Organic matter in the IDP samples is less aromatic than that in the CR chondrites, and its functional group chemistry is mainly characterized by C-O bonding and aliphatic C. Organic grains in CR chondrites are associated with carbonates and elemental Ca, which originate either from aqueous fluids or possibly an indigenous organic source. One distinct grain from the CR chondrite NWA 852 exhibits a rim structure only visible in chemical maps. The outer part is nanoglobular in shape, highly aromatic, and enriched in anomalous nitrogen. Functional group chemistry of the inner part is similar to spectra from IDP organic grains and less aromatic with nitrogen below the detection limit. The boundary between these two areas is very sharp. The direct association of both IDP-like organic matter with dominant C-O bonding environments and nanoglobular organics with dominant aromatic and C-N functionality within one unique grain provides for the first time to our knowledge strong evidence for organic synthesis in the early solar system activated by an anomalous nitrogen-containing parent body fluid. solar nebula | organic matter | meteorites | comets | transmission electron microscopy P rimitive extraterrestrial materials, including unmetamorphosed carbonaceous chondrites, chondritic porous interplanetary dust particles (CP-IDPs), carbonaceous Antarctic micrometeorites, and material from comet 81P/Wild 2, contain isotopically anomalous carbonaceous matter typically enriched in D and/or 15 N compared with the Earth and bulk meteorites (1-11). This carbonaceous matter occurs as diffuse material but also in the form of sub-μm-to μm-sized grains that are extremely enriched in D and/or 15 N and therefore stand out in isotopic maps as so-called "hot spots." These hot spots represent good candidates to study ancient organic compounds that may have served as precursors for the prebiotic history of the early Earth. In many, but not all, cases, the isotopic hot spots occur as so-called "nanoglobules," which are observed as hollow or compact carbonaceous sub-μm spheres in a wide range of primitive extraterrestrial samples (e.g., refs. 11-16). The most widely accepted theory for the origins of the anomalies invokes exothermic ion-molecule isotope exchange reactions at very low temperatures (<25 K) in cold interstellar clouds or the outer reaches of the nascent solar nebula (e.g., refs. 6, 7, 17, and 18). A second possible mechanism for the observed 15 N enrichments is N 2 self-shielding, in which optical depth effects lead to isotopeselective photodissociation (19)(20)(21)(22), but the applicability of the N 2 self-shielding m...

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“…Carbon and oxygen species often can be easier resolved in their K-edge XANES spectra [38]. Cu foil, and crystalline trisodium citrate as a reference.…”

Section: Xanesmentioning

confidence: 99%

“…Cu foil, and crystalline trisodium citrate as a reference. The C K-edge spectra are dominated by the resonance at 288.4 eV from electron transitions from C 1s to vacant antibonding  * states in COO -groups [38]; the peak is much higher and narrower, and its energy is somewhat less for trisodium citrate than for AgNPs. A shoulder at 287.5 eV should be assigned to aliphatic carbon, and broad maxima near 290 eV are attributable to alcohol groups, while signals from ketone groups expected at 286.1-286.5 eV are negligible.…”

Section: Xanesmentioning

confidence: 99%

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

Mikhlin

Vorobyev

Сайкова

et al. 2018

Applied Surface Science

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Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles 3 immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag + ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

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C 1s K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy for characterizing functional group chemistry of black carbon

Cited by 108 publications

References 59 publications

Use of biochar to enhance constructed wetland performance in wastewater reclamation

Use of biochar to enhance constructed wetland performance in wastewater reclamation

Fluid-induced organic synthesis in the solar nebula recorded in extraterrestrial dust from meteorites

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

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