scholarly journals Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

2014 ◽  
Vol 11 (5) ◽  
pp. 6815-6844
Author(s):  
S. C. Löhr ◽  
M. J. Kennedy
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
X Ray ◽  
Oceanic Anoxic Event ◽  
Carbon Burial ◽  
Anoxic Events ◽  
Mineral Surface Area

Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE2 at Demerara Rise was controlled by co-occurrence of anoxic bottom-water, sufficient productivity to saturate available mineral surfaces and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2=0.92) occurs across a range of TOC values from 9–33%. X-ray diffraction data indicates intercalation of OC in smectite interlayers while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE2 at Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.

scholarly journals Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

2014 ◽  
Vol 11 (18) ◽  
pp. 4971-4983 ◽  
Author(s):  
S. C. Löhr ◽  
M. J. Kennedy
Keyword(s):  
Organic Carbon ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Mineral Surface ◽  
X Ray ◽  
Oceanic Anoxic Event ◽  
Carbon Burial ◽  
Anoxic Events ◽  
Mineral Surface Area

Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE 2 at the Demerara Rise was controlled by the co-occurrence of anoxic bottom water, sufficient productivity to saturate available mineral surfaces, and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2 = 0.92) occurs across a range of total organic carbon (TOC) values from 9 to 33%. X-ray diffraction data indicate the intercalation of OC in smectite interlayers, while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE 2 at the Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE 2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.

Synthesis and Analysis of High Surface Area Vanadium Carbide Nanoparticles

2012 ◽  
Vol 585 ◽  
pp. 95-99 ◽  
Author(s):  
M. Mahajan ◽  
K. Singh ◽  
O.P. Pandey
Keyword(s):  
Surface Area ◽  
Vanadium Carbide ◽  
High Surface ◽  
High Surface Area ◽  
X Ray Diffraction ◽  
High Melting Point ◽  
X Ray ◽  
Transmission Electron ◽  
Product Powder ◽  
Scanning Electron

Vanadium carbide is known for its applications due to extreme hardness and high melting point. In this present work, vanadium carbide nanoparticles have been synthesized in a specially designed stainless steel autoclave by solvothermal route using vanadium pentoxide (V2O5) as precursor along with a hydrocarbon acetone (C3H6O) in the presence of reducing agent magnesium (Mg). The optimization of reaction time was studied at constant temperature of 800oC. The product powder was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscope (TEM) and Brunauer – Emmett – Teller (BET) techniques. The results indicate that the product was vanadium carbide having particle size of about 30 nm with high surface area.

scholarly journals Surface Modification Effect and Electrochemical Performance of LiOH-High Surface Activated Carbon as a Cathode Material in EDLC

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2187
Author(s):  
Zambaga Otgonbayar ◽  
Sunhye Yang ◽  
Ick-Jun Kim ◽  
Won-Chun Oh
Keyword(s):  
Activated Carbon ◽  
Cathode Material ◽  
Electrochemical Properties ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Oxidizing Agent ◽  
Peak Current ◽  
X Ray ◽  
Current Value

This study aimed to improve the performance of the activated carbon-based cathode by increasing the Li content and to analyze the effect of the combination of carbon and oxidizing agent. The crystal structure and chemical structure phase of Li-high surface area activated carbon material (Li-HSAC) was analyzed by X-ray diffraction (XRD) and Raman spectroscopy, the surface state and quantitative element by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and the surface properties with pore-size distribution by Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH) and t-plot methods. The specific surface area of the Li-YP80F is 1063.2 m2/g, micropore volume value is 0.511 cm3/g and mesopore volume is 0.143 cm3/g, and these all values are higher than other LiOH-treated carbon. The surface functional group was analyzed by a Boehm titration, and the higher number of acidic groups compared to the target facilitated the improved electrolyte permeability, reduced the interface resistance and increased the electrochemical properties of the cathode. The oxidizing agent of LiOH treated high surface area of activated carbon was used for the cathode material for EDLC (electric double layer capacitor) to determine its electrochemical properties and the as-prepared electrode retained excellent performance after 10 cycles and 100 cycles. The anodic and cathodic peak current value and peak segregation of Li-YP80F were better than those of the other two samples, due to the micropore-size and physical properties of the sample. The oxidation peak current value appeared at 0.0055 mA/cm2 current density and the reduction peak value at –0.0014 mA/cm2, when the Li-YP80F sample used to the Cu-foil surface. The redox peaks appeared at 0.0025 mA/cm2 and –0.0009 mA/cm2, in the case of using a Nickel foil, after 10 cycling test. The electrochemical stability of cathode materials was tested by 100 recycling tests. After 100 recycling tests, peak current drop decreased the peak profile became stable. The LiOH-treated high surface area of activated carbon had synergistically upgraded electrochemical activity and superior cycling stability that were demonstrated in EDLC.

scholarly journals Preparation of Ammonia Dealuminated Metakaolinite and Its Adsorption against Bixin

2020 ◽  
Vol 20 (4) ◽  
pp. 791
Author(s):  
Winda Rahmalia ◽  
Jean-Francois Fabre ◽  
Thamrin Usman ◽  
Zéphirin Mouloungui
Keyword(s):  
Surface Area ◽  
Room Temperature ◽  
High Surface ◽  
High Surface Area ◽  
Total Pore Volume ◽  
Adsorption Properties ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pseudo Second Order

This study aims to prepare dealuminated metakaolinite which has a high surface area by using NH4OH as an activator. The natural kaolinite sample was treated at 600 °C for 6 h in order to obtain metakaolinite. A dealuminated metakaolinite was then prepared by the repeated activation method using concentrated ammonia (5 M NH4OH) at room temperature. Depending on the nature of each type of material, natural kaolinite, NH4OH treated kaolinite, metakaolinite and NH4OH treated metakaolinite were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller (BET-N2) measurements. XRD and FTIR results confirmed that structural transformation from kaolinite to metakaolinite had occurred. According to SEM-EDS data, the activation of metakaolinite by NH4OH allowed the dealumination of metakaolinite. The increase in the Si/Al ratio was almost twice as high as in kaolinite. BET-N2 analysis showed that the specific surface area and the total pore volume increased significantly after activation. Its adsorption properties were tested against bixin. Bixin adsorption on dealuminated metakaolinite followed pseudo-second order kinetic where k2 = 0.20 g/mg min. The adsorption isotherm followed the Langmuir model where qm = 0.72 mg/g.

Flower Buds Like MgO Nanoparticles: From Characterisation to Indigo Carmine Elimination

2018 ◽  
Vol 73 (11) ◽  
pp. 975-983 ◽  
Author(s):  
A. Modwi ◽  
L. Khezami ◽  
Kamal K. Taha ◽  
Hajo Idriss
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Indigo Carmine ◽  
High Surface Area ◽  
Dye Adsorption ◽  
Nitrogen Adsorption ◽  
Magnesium Carbonate ◽  
Flower Buds ◽  
X Ray ◽  
Pseudo Second Order

AbstractHere, we demonstrate a pyrolysis route for the synthesis of flower buds like magnesium oxide nanoparticles using a magnesium carbonate precursor without additional chemicals. The effect of heating at different time intervals upon the structure and morphology of the acquired nanostructures were investigated via X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and Fourier transformation infrared spectroscopy. Nitrogen adsorption was employed to study its porosity. The obtained data confirmed the formation of target nanoparticles that exhibited increasing sizes as pyrolysis time was lengthened. As a consequence a high surface area up to 27 m2 g−1 was recorded for the sample heated for 1 h duration. Furthermore, Indigo Carmine dye adsorption was carried out using the largest surface area species which showed an adsorption capacity of 158 mg g−1. The adsorption was found to comply with the Langmuir isotherm and it follows the pseudo-second-order kinetics. The diffusion process showed intra-particle along with film diffusion mode.

scholarly journals Growth of Hierarchically Structured High-Surface Area Alumina on FeCrAl Alloy Wires

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Chandni Rallan ◽  
Aaron Akah ◽  
Patrick Hill ◽  
Arthur Garforth
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
X Ray Diffraction ◽  
Entire Study ◽  
X Ray ◽  
Thermogravimetric Analyzer ◽  
Fecral Alloy ◽  
Time Periods ◽  
Metastable Alumina

The formation of metastable alumina phases due to the oxidation of commercial FeCrAl alloy wires (0.5 mm thickness) at various temperatures and time periods has been examined. Samples were isothermally oxidised in air using a thermogravimetric analyzer (TGA). The morphology of the oxidised samples was analyzed using an Electronic Scanning Electron Microscope (ESEM) and X-ray on the surface analysis was done using an Energy Dispersive X-Ray (EDX) analyzer. The technique of X-Ray Diffraction (XRD) was used to characterize the phase of the oxide growth. The entire study showed that it was possible to grow high-surface area gamma alumina on the FeCrAl alloy wire surfaces when isothermally oxidised above 800°C over several hours.

Preparation of High Surface Area Ni-SDC Cermets Using a Surfactant-Assisted Co-Precipitation Method

2006 ◽  
Vol 942 ◽  
Author(s):  
Sang Joon Park ◽  
Tae Wook Eom ◽  
Jae Eun Oh ◽  
Hae Kwang Yang ◽  
Kyung Hwan Kim
Keyword(s):  
Surface Area ◽  
Cetyltrimethylammonium Bromide ◽  
High Surface ◽  
High Surface Area ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Phases ◽  
Co Precipitation ◽  
Surfactant Assisted

ABSTRACTA surfactant-assisted co-precipitation method was employed for obtaining high surface area Ni-SDC with improved structural properties for SOFC applications. In the work, a cationic surfactant, cetyltrimethylammonium bromide(CTAB) was employed with NiCl2, SmCl3 and CeCl3 as precursors and NH4OH as mineralizer. The elimination of surfactants upon calcination gives rise to the formation of high surface area NiO-SDC. When calcined at 600°C, the powders with surface area of 249 m2/g, were obtained and the pore size was 14.45 nm. The powders consist of two phases, the cubic NiO and SDC confirmed with X-ray diffraction identification.

scholarly journals Syntheses of Nanostructured Magnesium Carbonate Powders with Mesoporous Structures from Carbon Dioxide

2021 ◽  
Vol 11 (3) ◽  
pp. 1141
Author(s):  
Fernando J. Rodríguez-Macías ◽  
José E. Ortiz-Castillo ◽  
Erika López-Lara ◽  
Alejandro J. García-Cuéllar ◽  
José L. López-Salinas ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Magnesium Carbonate ◽  
Synthesis Methods ◽  
X Ray Diffraction ◽  
Aqueous Synthesis ◽  
Synthesis Time ◽  
X Ray

In this work, we present the results of two synthesis approaches for mesoporous magnesium carbonates, that result in mineralization of carbon dioxide, producing carbonate materials without the use of cosolvents, which makes them more environmentally friendly. In one of our synthesis methods, we found that we could obtain nonequilibrium crystal structures, with acicular crystals branching bidirectionally from a denser core. Both Raman spectroscopy and X-ray diffraction showed these crystals to be a mixture of sulfate and hydrated carbonates. We attribute the nonequilibrium morphology to coprecipitation of two salts and short synthesis time (25 min). Other aqueous synthesis conditions produced mixtures of carbonates with different morphologies, which changed depending on drying temperature (40 or 100 °C). In addition to aqueous solution, we used supercritical carbon dioxide for synthesis, producing a hydrated magnesium carbonate, with a nesquehonite structure, according to X-ray diffraction. This second material has smaller pores (1.01 nm) and high surface area. Due to their high surface area, these materials could be used for adsorbents and capillary transport, in addition to their potential use for carbon capture and sequestration.

scholarly journals Operando X-ray characterization of high surface area iridium oxides to decouple their activity losses for the oxygen evolution reaction

2019 ◽  
Vol 12 (10) ◽  
pp. 3038-3052 ◽  
Author(s):  
Mauro Povia ◽  
Daniel F. Abbott ◽  
Juan Herranz ◽  
Adrian Heinritz ◽  
Dmitry Lebedev ◽  
...  
Keyword(s):  
Surface Area ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Oxide Catalysts ◽  
X Ray ◽  
Iridium Oxides ◽  
Evolution Of Oxygen

Operando X-ray techniques allow an unprecedented, quantitative discrimination of the instability mechanisms affecting Ir-oxide catalysts for the evolution of oxygen.

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