Influence of Different Birnessite Interlayer Alkali Cations on Catalytic Oxidation of Soot and Light Hydrocarbons

A series of layered birnessite (AMn4O8) catalysts containing different alkali cations (A = H+, Li+, Na+, K+, Rb+, or Cs+) was synthesized. The materials were thoroughly characterized using X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, Raman spectroscopy, specific surface area analysis, work function, thermogravimetry/differential scanning calorimetry, and transmission electron microscopy. The catalytic activity in soot combustion in different reaction modes was investigated (tight contact, loose contact, loose contact with NO addition). The activity in the oxidation of light hydrocarbons was evaluated by tests with methane and propane. The obtained results revealed that alkali-promoted manganese oxides are highly catalytically active in oxidative reactions. In soot combustion, the reaction temperature window was shifted by 195 °C, 205 °C, and 90 °C in tight, loose + NO, and loose contact conditions against uncatalyzed oxidation, respectively. The catalysts were similarly active in hydrocarbon combustion, achieving a 40% methane conversion at 600 °C and a total propane conversion at ~450 °C. It was illustrated that the difference in activity between tight and loose contacts can be successfully bridged in the presence of NO due to its facile transformation into NO2 over birnessite. The particular activity of birnessite with H+ cations paves the road for the further development of the active phase, aiming at alternative catalytic systems for efficient soot, light hydrocarbons, and volatile organic compounds removal in the conditions present in combustion engine exhaust gases.

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pH-controlled synthesis of sustainable lauric acid/SiO2 phase change material for scalable thermal energy storage

Scientific Reports ◽

10.1038/s41598-021-94571-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shafiq Ishak ◽

Soumen Mandal ◽

Han-Seung Lee ◽

Jitendra Kumar Singh

Keyword(s):

Electron Microscopy ◽

Phase Change ◽

Lauric Acid ◽

Photoelectron Spectroscopy ◽

Phase Change Materials ◽

Precursor Solution ◽

Thermal Reliability ◽

Scanning Calorimetry ◽

X Ray ◽

Heating And Cooling

AbstractLauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process.

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Preparation and Characterization of Ni2+-Montmorillonite/Polyvinyl Alcohol Water-Soluble Nanocomposite Film

Polymers and Polymer Composites ◽

10.1177/096739110501300811 ◽

2005 ◽

Vol 13 (8) ◽

pp. 839-846 ◽

Cited By ~ 4

Author(s):

Li-Ping Wang ◽

Yun-Pu Wang ◽

Fa-Ai Zhang

Keyword(s):

Polyvinyl Alcohol ◽

Photoelectron Spectroscopy ◽

Thermal Characteristics ◽

Water Soluble ◽

Scanning Calorimetry ◽

Xps Spectra ◽

X Ray ◽

Alcohol Water ◽

Ft Ir ◽

Silicate Layers

A new type of nano-composite film was prepared from polyvinyl alcohol, Ni2+-montmorillonite (Ni2+-MMT), defoamer, a levelling agent and a plasticizer. Its thermal characteristics were studied by Differential Scanning Calorimetry (DSC). The intermolecular interactions were measured by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the tensile strength (TS) and elongation at break (%E) were measured. The microstructures were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). FT-IR and XPS spectra indicated that cross-linking has taken place between PVA and Ni2+-MMT. XRD and AFM indicate that the PVA molecules had inserted themselves into the silicate layers of MMT, exfoliating them and dispersing them randomly into the PVA matrix. Compared to pure PVA film, the TS of the films was increased and %E decreased when the Ni2+-Montmorillonite was added and the dissolution temperature of the film was also reduced.

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Copper microsphere hybrid mesoporous carbon as matrix for preparation of shape-stabilized phase change materials with improved thermal properties

Scientific Reports ◽

10.1038/s41598-020-73114-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yi Liu ◽

Yan Chen ◽

Junwei Zhang ◽

Junkai Gao ◽

Zhi Han

Keyword(s):

Thermal Properties ◽

Phase Change ◽

Photoelectron Spectroscopy ◽

Mesoporous Carbon ◽

Phase Change Materials ◽

Copper Ions ◽

Thermal Constant ◽

Step Method ◽

Scanning Calorimetry ◽

X Ray

Abstract Copper microsphere hybrid mesoporous carbon (MPC-Cu) was synthesized by the pyrolysis of polydopamine microspheres doped with copper ions that were prepared using a novel, facile and simple one-step method of dopamine biomimetic polymerization and copper ion adsorption. The resulting MPC-Cu was then used as a supporter for polyethylene glycol (PEG) to synthesize shape-stabilized phase change materials (PEG/MPC-Cu) with enhanced thermal properties. PEG/MPC-Cu was studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry and thermal constant analysis. The results demonstrated that the thermal conductivity of PEG/MPC-Cu was 0.502 W/(m K), which increased by 100% compared to pure PEG [0.251 W/(m K)]. The melting enthalpy of PEG/MPC-Cu was 95.98 J/g, indicating that PEG/MPC-Cu is a promising candidate for future thermal energy storage applications. In addition, the characterization results suggested that PEG-MPC-Cu possessed high thermal stability. Therefore, the method developed in this paper for preparing shape-stabilized phase change materials with improved thermal properties has substantial engineering application prospects.

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Effect of the Degree of Substitution on the Hydrophobicity, Crystallinity, and Thermal Properties of Lauroylated Amaranth Starch

Polymers ◽

10.3390/polym12112548 ◽

2020 ◽

Vol 12 (11) ◽

pp. 2548

Author(s):

Vicente Espinosa-Solis ◽

Yunia Verónica García-Tejeda ◽

Everth Jimena Leal-Castañeda ◽

Víctor Barrera-Figueroa

Keyword(s):

Photoelectron Spectroscopy ◽

Thermal Characterization ◽

Fatty Acyl ◽

Degree Of Substitution ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Amaranthus Hypochondriacus ◽

Two Samples ◽

Acyl Chains

In this paper, we consider amaranth starch extracted from the seeds of Amaranthus hypochondriacus L. An amphiphilic character is conferred to the starch by a chemical modification, which involves an esterification by lauroyl chloride at three modification levels. The degree of substitution (DS) after the modification ranged from 0.06 to 1.16. X-ray photoelectron spectroscopy analysis confirmed the presence of fatty acyl chains on the surface of the esterified starches. The hydrophobicity of starches was confirmed by their adsorption isotherms, which showed a decrease in the moisture adsorption of lauroylated as DS increased. X-ray diffraction analysis revealed a higher crystallinity, which was observed in the two samples subjected to the highest levels of modification. A higher crystallinity is related to a higher gelatinization enthalpy. These results are in agreement with the thermal characterization obtained by differential scanning calorimetry (DSC). An inhibition of the retrogradation properties of lauroylated amaranth starches was also observed.

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STUDIES ON SURFACE STRUCTURE, MORPHOLOGY AND COMPOSITION OF Co–W COATINGS ELECTRODEPOSITED WITH DIRECT AND PULSE CURRENT USING GLUCONATE BATH

Surface Review and Letters ◽

10.1142/s0218625x13500066 ◽

2013 ◽

Vol 20 (01) ◽

pp. 1350006 ◽

Cited By ~ 6

Author(s):

PARTHASARATHI BERA ◽

H. SEENIVASAN ◽

K. S. RAJAM

Keyword(s):

Photoelectron Spectroscopy ◽

Pulse Current ◽

Diffraction Field ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Force Microscopy ◽

Dsc Studies ◽

Atomic Force ◽

Electrodeposited Coating

Co–W alloy coatings were deposited with direct current (DC) and pulse current (PC) electrodeposition methods using gluconate bath at pH5 and characterized by X-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). DSC studies hint at the possibility of formation of metallic glasses. Detailed XPS studies of these alloy coatings have been carried out to compare elemental states and composition of Co and W in DC and PC electrodeposited alloys. DC-plated alloy has significant amount of Co and W metal along with their respective oxidized species. In contrast, mainly oxidized metals are present in the following layers of as-deposited coatings prepared with PC plating. Concentration of Co metal is observed to increase during sputtering, whereas there is no change in W6+ concentration. Microhardness measurement of all the Co–W coatings shows higher hardness compared to Co metal and 1:1 and 1:4 PC electrodeposited coatings show little higher hardness compared to 1:2 PC electrodeposited coating.

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Fabrication of silane-grafted graphene oxide and its effect on the structural, thermal, mechanical, and hysteretic behavior of polyurethane

Scientific Reports ◽

10.1038/s41598-020-76153-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Joo Hyung Lee ◽

Seong Hun Kim

Keyword(s):

Mechanical Properties ◽

Graphene Oxide ◽

Photoelectron Spectroscopy ◽

Testing Machine ◽

Hysteretic Behavior ◽

Hexamethylene Diisocyanate ◽

Scanning Calorimetry ◽

Functionalized Graphene Oxide ◽

X Ray ◽

Ft Ir

Abstract Incorporation of nanofillers into polyurethane (PU) is a promising technique for enhancing its thermal and mechanical properties. Silane grafting has been used as a surface treatment for the functionalization of graphene oxide (GO) with numerous reactive sites dispersed on its basal plane and edge. In this study, amine-grafted GO was prepared using silanization of GO with (3-aminopropyl)triethoxysilane. The functionalized graphene oxide (fGO) was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy. Next, it was introduced in PU fabricated using polycaprolactone diol, castor oil, and hexamethylene diisocyanate. The fGO–PU nanocomposites were in turn characterized by FT-IR, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and a universal testing machine. The results obtained from these analyses showed changes in structural thermal properties, as well as improved thermal stability and mechanical properties because of the strong interfacial adhesion between the fGO and the PU matrix.

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Mechanism and Improved Dissolution of Glycyrrhetinic Acid Solid Dispersion by Alkalizers

Pharmaceutics ◽

10.3390/pharmaceutics12010082 ◽

2020 ◽

Vol 12 (1) ◽

pp. 82 ◽

Cited By ~ 2

Author(s):

Luning Dong ◽

Yaping Mai ◽

Qiang Liu ◽

Wannian Zhang ◽

Jianhong Yang

Keyword(s):

Solid Dispersion ◽

Photoelectron Spectroscopy ◽

Molecular Model ◽

In Vitro Release ◽

Glycyrrhetinic Acid ◽

Dissolution Mechanism ◽

Scanning Calorimetry ◽

Ionization Degree ◽

X Ray

The purpose of this study was to increase the dissolution of glycyrrhetinic acid (GA) by preparing ternary solid dispersion (TSD) systems containing alkalizers, and to explore the modulating mechanism of alkalizers in solid dispersion systems. GA TSDs were prepared by hot melt extrusion (HME) with Kollidon® VA64 as the carrier and L-arginine/meglumine as the alkalizers. The in vitro release of the TSD was investigated with a dissolution test, and the dissociation constant (pKa) was used to describe the ionization degree of the drug in different pH buffers. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), and a molecular model were used for solid-state characterizations and to study the dissolution mechanism of the TSDs. It was evident that the dissolution of GA significantly increased as a result of the TSD compared to the pure drug and binary solid dispersion. SEM, DSC, and XPRD data showed that GA transformed into an amorphous form in TSD. As illustrated by FTIR, Raman, XPS, and molecular docking, high binding energy ion-pair complexes formed between GA and the alkalizers during the process of HME. These can destroy the H-bond between GA molecules. Further, intermolecular H-bonds formed between the alkalizers and Kollidon® VA64, which can increase the wettability of the drug. Our results will significantly improve the solubility and dissolution of GA. In addition, the lower pKa value of TSD indicates that higher ionization is beneficial to the dissolution of the drug. This study should facilitate further developments of TSDs containing alkalizers to improve the dissolution of weakly acidic drugs and gain a richer understanding of the mechanism of dissolution.

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Porphyrin–Nanodiamond Hybrid Materials—Active, Stable and Reusable Cyclohexene Oxidation Catalysts

Catalysts ◽

10.3390/catal10121402 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1402

Author(s):

Lucas D. Dias ◽

Fábio M. S. Rodrigues ◽

Mário J. F. Calvete ◽

Sónia A. C. Carabineiro ◽

Marisa D. Scherer ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Allylic Oxidation ◽

Reusable Catalyst ◽

Turnover Number ◽

Scanning Calorimetry ◽

X Ray ◽

Amine Functionalized ◽

Major Loss ◽

Covalently Linked ◽

Catalytic Cycles

The quest for active, yet “green” non-toxic catalysts is a continuous challenge. In this work, covalently linked hybrid porphyrin–nanodiamonds were prepared via ipso nitro substitution reaction and characterized by X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, infrared spectroscopy (IR) and thermogravimetry-differential scanning calorimetry (TG-DSC). The amine-functionalized nanodiamonds (ND@NH2) and 2-nitro-5,10,15,20-tetra(4-trifluoromethylphenyl)porphyrin covalently linked to nanodiamonds (ND@βNH-TPPpCF3) were tested using Allium cepa as a plant model, and showed neither phytotoxicity nor cytotoxicity. The hybrid nanodiamond–copper(II)–porphyrin material ND@βNH-TPPpCF3-Cu(II) was also evaluated as a reusable catalyst in cyclohexene allylic oxidation, and displayed a remarkable turnover number (TON) value of ≈265,000, using O2 as green oxidant, in the total absence of sacrificial additives, which is the highest activity ever reported for said allylic oxidation. Additionally, ND@βNH-TPPpCF3-Cu(II) could be easily separated from the reaction mixture by centrifugation, and reused in three consecutive catalytic cycles without major loss of activity.

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Nanostructured manganese oxides and their composites with carbon nanotubes as electrode materials for energy storage devices

Pure and Applied Chemistry ◽

10.1351/pac200880112327 ◽

2008 ◽

Vol 80 (11) ◽

pp. 2327-2343 ◽

Cited By ~ 26

Author(s):

V. Subramanian ◽

Hongwei Zhu ◽

Bingqing Wei

Keyword(s):

Electron Microscopy ◽

Carbon Nanotubes ◽

Photoelectron Spectroscopy ◽

Manganese Oxides ◽

Electrode Materials ◽

Electrochemical Impedance ◽

Analytical Techniques ◽

Energy Storage Devices ◽

X Ray ◽

Storage Devices

Manganese oxides have been synthesized by a variety of techniques in different nanostructures and studied for their properties as electrode materials in two different storage applications, supercapacitors (SCs) and Li-ion batteries. The composites involving carbon nanotubes (CNTs) and manganese oxides were also prepared by a simple room-temperature method and evaluated as electrode materials in the above applications. The synthesis of nanostructured manganese oxides was carried out by simple soft chemical methods without any structure directing agents or surfactants. The prepared materials were well characterized using different analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), surface area studies, etc. The electrochemical properties of the nanostructured manganese oxides and their composites were studied using cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopic (EIS) studies. The influence of structural/surface properties on the electrochemical performance of the synthesized manganese oxides is reviewed.

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Sputter-deposition and characterization of paramelaconite

Journal of Materials Research ◽

10.1557/jmr.2003.0212 ◽

2003 ◽

Vol 18 (7) ◽

pp. 1535-1542 ◽

Cited By ~ 37

Author(s):

K. J. Blobaum ◽

D. Van Heerden ◽

A. J. Wagner ◽

D. H. Fairbrother ◽

T. P. Weihs

Keyword(s):

Photoelectron Spectroscopy ◽

Metastable Phase ◽

Heat Of Formation ◽

Sputter Deposition ◽

Scanning Calorimetry ◽

X Ray ◽

Multilayer Foils ◽

Out Of Plane ◽

Processing Techniques

While processing techniques for deposition of CuOx/Al multilayer foils were being developed, a method for synthesizing paramelaconite (Cu4O3) was serendipitously discovered. These paramelaconite films were successfully synthesized by sputter-deposition from a CuO target. Milligram quantities of uncontaminated material were produced enabling new studies of the morphology, stoichiometry, and thermodynamics of this unique copper oxide. At moderate temperatures, equiaxed paramelaconite grains deposited with a strong out-of-plane texture; at lower temperatures the paramelaconite grains showed no texture but were columnar in geometry. X-ray photoelectron spectroscopy showed that the as-deposited Cu4O3 had a nonstoichiometric Cu:O ratio of 1.7:1; the ratio of Cu+ to Cu2+ was 1.8:1. On heating, this phase decomposed into CuO and Cu2O at temperatures ranging from 400 to 530 °C. Using differential scanning calorimetry, the heat of formation and Gibbs free energy for Cu4O3 were estimated to be −453 and −279 kJ/mol, respectively. On the basis of these calculations and our observations, we confirmed that Cu4O3 is a metastable phase.

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