scholarly journals Adsorptive-Oxidative Removal of Sulfides from Water by MnO2-Loaded Carboxylic Cation Exchangers

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5124
Author(s):  
Łukasz J. Wilk ◽  
Agnieszka Ciechanowska ◽  
Elżbieta Kociołek-Balawejder
Keyword(s):  
Electrostatic Interactions ◽  
Energy Dispersive Spectrometry ◽  
Mercury Porosimetry ◽  
Nitrogen Adsorption ◽  
Ionic Form ◽  
X Ray ◽  
Cation Exchangers ◽  
Nitrogen Adsorption Isotherms ◽  
The Impact ◽  
Supporting Materials

Hybrid ion exchangers (HIX) containing manganese(IV) oxide (MnO2) based on macroporous and gel-type carboxylic cation exchangers as supporting materials were obtained. The hybrid materials were characterized using scanning electron microscopy with energy dispersive spectrometry (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and nitrogen adsorption isotherms at 77 K and mercury porosimetry. HIX with introduced MnO2 (20.0–32.8 wt% Mn) were tested for removal of dissolved sulfides from anoxic aqueous solutions with 100–500 mg S2−/dm3 concentrations. The process proceeded effortlessly at pH 10–13 despite unfavorable electrostatic interactions of the reactants. The highest exhibited sorption capacity was 144.3 ± 7.1 mg S2−/g. Approximately 65% of dissolved sulfides were oxidized to S2O32− ions and repelled from HIX structure. On average, 13% of sulfide removal products were adsorbed by the MnO2 surface. The impact of MnO2 load and the ionic form of HIX functional groups on removal of sulfides and resulting products was examined. The mechanism of the process is suggested.

Structure of Zirconia Nanoparticles used for Pillaring of Clay

2001 ◽  
Vol 703 ◽  
Author(s):  
V. A. Sadykov ◽  
T. G. Kuznetsova ◽  
V. P. Doronin ◽  
T. P. Sorokina ◽  
D. I. Kochubei ◽  
...  
Keyword(s):  
Alkaline Earth ◽  
Nitrogen Adsorption ◽  
Structural Features ◽  
Concentration Addition ◽  
X Ray ◽  
Oxygen Anions ◽  
Nitrogen Adsorption Isotherms ◽  
Alkaline Earth Chlorides ◽  
Zirconium Concentration ◽  
Zirconia Nanoparticles

ABSTRACTSAXS and EXAFS were applied to study genesis of polynuclear zirconium hydroxyspecies in pillaring solutions as dependent upon the zirconium concentration, addition of alkaline-earth chlorides and aging. After the montmorillonite clay pillaring, the structure of zirconium nanopillars was characterized by applying X-ray structural analysis, UV-Vis, FTIRS of adsorbed CO and nitrogen adsorption isotherms. Main pillaring species appear to be nanorods comprised of several Zr4 tetramers. Basic structural features of the tetramers are preserved in zirconia nanoparticles fixed between alumosilicate layers in pillared clays. In calcined samples, those nanoparticles contain only bridging hydroxyls and/or oxygen anions responsible for bonding within pillars and between pillars and clay sheets.

scholarly journals Synergistic Action of Montmorillonite with an Intumescent Formulation: The Impact of the Nature and the Strength of Acidic Sites on the Flame-Retardant Properties of Polypropylene Composites

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2781
Author(s):  
Raíssa Carvalho Martins ◽  
Michelle Jakeline Cunha Rezende ◽  
Marco Antonio Chaer Nascimento ◽  
Regina Sandra Veiga Nascimento ◽  
Simone Pereira da Silva Ribeiro
Keyword(s):  
Flame Retardant ◽  
Nitrogen Adsorption ◽  
Synergistic Action ◽  
Limit Oxygen Index ◽  
Esterification Reaction ◽  
X Ray ◽  
Polypropylene Composites ◽  
Acidic Sites ◽  
Flame Retardant Properties ◽  
The Impact

A raw montmorillonite (Mt) was submitted to different acidic activation times in order to investigate the influence of the strength and the nature (Brønsted and Lewis) of acidic sites on the synergistic action with an intumescent formulation (IF) composed of ammonium polyphosphate (APP) and pentaerythritol (PER) when incorporated into a polypropylene (PP) matrix. The acidity of the Mt samples was quantified by ammonia temperature-programmed desorption (TPD-NH3) and Fourier transform infrared spectroscopy (FTIR) with pyridine adsorption. The mineral clays were also characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), nitrogen adsorption analysis and particle size distribution. Thermogravimetric analysis (TGA), limit oxygen index (LOI) and UL-94 were performed to evaluate the flame-retardant properties and the thermal stability. The TGA results show that the final residue increased 2 to 3 fold in comparison to the values predicted theoretically. The flammability properties achieved a maximum for the system containing an excess of moderate-strength Brønsted sites relative to the Lewis ones, reaching 38% in the LOI test. This result suggests that the presence of these Brønsted acidic sites is important, as they take part in the esterification reaction between APP and PER which gives rise to the char formation. The FTIR-Pyr adsorption and flammability results indicate that both the nature and strength of the acidic sites influence the flame-retardant properties.

Surface fractal dimensions of synthetic clay-hydrous iron oxide associations from nitrogen adsorption isotherms and mercury porosimetry

Clay Minerals ◽  
1996 ◽  
Vol 31 (3) ◽  
pp. 355-363 ◽  
Author(s):  
R. Cells ◽  
J. Cornejo ◽  
M. C. Hermosin
Keyword(s):  
Fractal Dimension ◽  
Iron Oxide ◽  
Adsorption Isotherms ◽  
Mercury Porosimetry ◽  
Oxide Coating ◽  
Nitrogen Adsorption ◽  
Medium Size ◽  
Surface Fractal ◽  
Hydrous Iron Oxide ◽  
Nitrogen Adsorption Isotherms

AbstractModel associations of layer silicates (kaolinite and montmorillonite) and iron oxyhydroxides were obtained by precipitating hydrous iron oxide in clay suspensions at different loading. The porosity of these clay-hydrous iron oxide associations was studied in the macro- and mesopore range by mercury intrusion porosimetry (MIP) and in the micropore region by nitrogen adsorption isotherms, being the fractal geometry applied to the approaches used in porosity studies. Results of nitrogen adsorption isotherms showed that surface area and microporosity of kaolinite and montmorillonite increased upon Fe precipitation, especially for montmorillonite. This process is accompanied by an increase in the surface fractal dimension Ds(N2) by the presence of hydrous iron oxide coating the clay particles. Results of MIP also showed a decrease in the pore volume by Fe precipitation on montmorillonite due to a decrease in the number of large pores and a development of new medium-size pores. An increase of the fractal dimension Ds(Hg) was also observed.

scholarly journals Impedimetric Detection of Ammonia and Low Molecular Weight Amines in the Gas Phase with Covalent Organic Frameworks

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1385 ◽  
Author(s):  
Andrés Rodríguez ◽  
Elio Rico ◽  
Cesar Sierra ◽  
Oscar Rodríguez
Keyword(s):  
Molecular Weight ◽  
Room Temperature ◽  
Nitrogen Adsorption ◽  
Low Molecular Weight ◽  
Covalent Organic Frameworks ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Nitrogen Adsorption Isotherms ◽  
Significant Interference

Two Covalent Organic Frameworks (COF), named TFP-BZ and TFP-DMBZ, were synthesized using the imine condensation between 1,3,5-triformylphloroglucinol (TFP) with benzidine (BZ) or 3,3-dimethylbenzidine (DMBZ). These materials were deposited, such as films over interdigitated electrodes (IDE), by chemical bath deposition, giving rise to TFP-BZ-IDE and TFP-DMBZ-IDE systems. The synthesized COFs powders were characterized by Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared spectroscopy (FT-IR), solid-state Nuclear Magnetic Resonance (ssNMR), nitrogen adsorption isotherms, Scanning Electron Microscopy (SEM), and Raman spectroscopy, while the films were characterized by SEM and Raman. Ammonia and low molecular weight amine sensing were developed with the COF film systems using the impedance electrochemical spectroscopy (EIS). Results showed that the systems TFP-BZ-IDE and TFP-DMBZ-IDE detect low molecular weight amines selectively by impedimetric analysis. Remarkably, with no significant interference by other atmospheric gas compounds such as nitrogen, carbon dioxide, and methane. Additionally, both COF films presented a range of sensitivity at low amine concentrations below two ppm at room temperature.

Analysis of Pore Structure on Carbon Powder of Hemp Straw

2010 ◽  
Vol 177 ◽  
pp. 640-642 ◽  
Author(s):  
Ling Xuan Meng ◽  
Jian Min Gao ◽  
Tian Ma ◽  
Zi Li Yan
Keyword(s):  
Electron Microscopy ◽  
Pore Structure ◽  
Mercury Porosimetry ◽  
Nitrogen Adsorption ◽  
Size Analysis ◽  
Carbon Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sic Ceramics ◽  
Transmission Electron

Reaction-formed silicon carbide (RF-SiC) ceramics can be prepared by melt Si-infiltration of the carbon preform which fabricated by casting of carbon powder of hemp straw. In order to make clear the pore structure of the carbon powder of hemp straw which affect the mechanical property of RF-SiC ceramics, the morphology and inherent pore structure of carbon powder of hemp straw were characterized with powder X-ray diffraction, laser diffraction size analysis, scanning electron microscopy, transmission electron microscopy, mercury porosimetry and nitrogen adsorption. The results indicated that some parts of interconnected macroporous and mesoporous structures of hemp straw still remained after carbonization and the RF-SiC ceramics with outstanding performance can be fabricated with this carbon powder by melt Si-infiltration of the porous preform

scholarly journals Influence of Selected Alkoxysilanes on Dispersive Properties and Surface Chemistry of Titanium Dioxide and TiO2–SiO2Composite Material

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Katarzyna Siwińska-Stefańska ◽  
Filip Ciesielczyk ◽  
Magdalena Nowacka ◽  
Teofil Jesionowski
Keyword(s):  
Composite Material ◽  
Titanium Dioxide ◽  
Sodium Silicate Solution ◽  
Nitrogen Adsorption ◽  
Silicate Solution ◽  
Scattering Method ◽  
X Ray ◽  
Titanium Sulfate ◽  
X Ray Scattering ◽  
Nitrogen Adsorption Isotherms

The paper reports on characterisation of titanium dioxide and coprecipitated TiO2–SiO2composite material functionalised with selected alkoxysilanes. Synthetic composite material was obtained by an emulsion method with cyclohexane as the organic phase, titanium sulfate as titanium precursor, and sodium silicate solution as precipitating agent were applied. Structures of titania and composite material samples were studied by the wide angle X-ray scattering method. The chemical composition of TiO2–SiO2composite material precipitated was evaluated based on the energy dispersive X-ray spectroscopy technique. The functionalised TiO2and TiO2–SiO2composite material were thoroughly characterised to determine the yield of functionalisation with silanes. The characterisation included determination of dispersion and morphology of the systems (particle size distribution, scanning electron microscope images), adsorption properties (nitrogen adsorption isotherms), and electrokinetic properties (zeta potential).

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

Synthesis of dispersed mesoporous powders solid solution Zr0.88Ce0.12O2 for catalyst carrier of the conversion of methane to synthesis –gas

2020 ◽  
pp. 73-83
Author(s):  
L. V. Morozova ◽  
◽  
I. A. Drozdova ◽  
Keyword(s):  
Solid Solution ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Primary Crystal ◽  
X Ray ◽  
Catalyst Carrier ◽  
Conversion Of Methane ◽  
Deposition Processes ◽  
Zirconia Oxide ◽  
Coprecipitation Of Hydroxides

The xerogels in the system 0.88 mol.% ZrO2 − 0.12 mol.% CeO2 were obtained by the method of coprecipitation in a neutral (pH = 7) and slightly alkaline (pH = 9) medium under the influence of ultrasound with the size of the agglomerates 70 – 230 nm. It is shown that the coprecipitation of hydroxides of zirconium and cerium at pH = 9 with the use of ultrasonic treatment facilitates the formation of a primary crystal is symbolic of the particles in the xerogel, whose size is ~ 5 nm, whereas the xerogel synthesized in a neutral environment consists only of the x-ray amorphous phase. The effect of pH-precipitation on deposition processes of dehydration of the xerogels and crystallization solid solution based on zirconia oxide in the metastable pseudocubic modification (с′-ZrO2) was discovered. It was found that in the temperature range 500 – 800 °C there is a phase transition с′-ZrO2 → t-ZrO2, the size of the crystallites of the formed tetragonal solid solutions is 8 and 11 nm. The method of low-temperature nitrogen adsorption were investigated dispersion properties and characteristics of the pore structure of the powders of the solid solution Zr0.88Ce0.12O2. It is determined that the specific surface area of t-ZrO2 samples obtained after firing at 800 °C is 117 and 178 m2/g, the total pore volume reaches 0.300 − 0.325 cm3/g, the pore size distribution is monomodal and is in the range of 2 − 8 nm. The effect of thermal “aging” at a temperature of 800 °C (40 h) on the structure and dispersion of the solid solution t-ZrO2 powders was studied.

Analyzing the Impact of X-Ray Tomography on the Reliability of Integrated Circuits

2015 ◽  
Author(s):  
Halit Dogan ◽  
Md Mahbub Alam ◽  
Navid Asadizanjani ◽  
Sina Shahbazmohamadi ◽  
Domenic Forte ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
3D Imaging ◽  
Three Dimensional ◽  
Serial Sectioning ◽  
Promising Technique ◽  
Flash Memories ◽  
X Ray ◽  
3D Information ◽  
The Impact

Abstract X-ray tomography is a promising technique that can provide micron level, internal structure, and three dimensional (3D) information of an integrated circuit (IC) component without the need for serial sectioning or decapsulation. This is especially useful for counterfeit IC detection as demonstrated by recent work. Although the components remain physically intact during tomography, the effect of radiation on the electrical functionality is not yet fully investigated. In this paper we analyze the impact of X-ray tomography on the reliability of ICs with different fabrication technologies. We perform a 3D imaging using an advanced X-ray machine on Intel flash memories, Macronix flash memories, Xilinx Spartan 3 and Spartan 6 FPGAs. Electrical functionalities are then tested in a systematic procedure after each round of tomography to estimate the impact of X-ray on Flash erase time, read margin, and program operation, and the frequencies of ring oscillators in the FPGAs. A major finding is that erase times for flash memories of older technology are significantly degraded when exposed to tomography, eventually resulting in failure. However, the flash and Xilinx FPGAs of newer technologies seem less sensitive to tomography, as only minor degradations are observed. Further, we did not identify permanent failures for any chips in the time needed to perform tomography for counterfeit detection (approximately 2 hours).

scholarly journals The role of point-of-care ultrasound in the diagnosis of pericardial effusion: a single academic center retrospective study

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Matthew G. Hanson ◽  
Barry Chan
Keyword(s):  
Pericardial Effusion ◽  
Point Of Care ◽  
Physical Exam ◽  
Right Atrial ◽  
Point Of Care Ultrasound ◽  
X Ray ◽  
Average Systolic Blood Pressure ◽  
Time To Diagnosis ◽  
Clinically Significant ◽  
The Impact

Abstract Background Symptomatic pericardial effusion (PCE) presents with non-specific features and are often missed on the initial physical exam, chest X-ray (CXR), and electrocardiogram (ECG). In extreme cases, misdiagnosis can evolve into decompensated cardiac tamponade, a life-threatening obstructive shock. The purpose of this study is to evaluate the impact of point-of-care ultrasound (POCUS) on the diagnosis and therapeutic intervention of clinically significant PCE. Methods In a retrospective chart review, we looked at all patients between 2002 and 2018 at a major Canadian academic hospital who had a pericardiocentesis for clinically significant PCE. We extracted the rate of presenting complaints, physical exam findings, X-ray findings, ECG findings, time-to-diagnosis, and time-to-pericardiocentesis and how these were impacted by POCUS. Results The most common presenting symptom was dyspnea (64%) and the average systolic blood pressure (SBP) was 120 mmHg. 86% of people presenting had an effusion > 1 cm, and 89% were circumferential on departmental echocardiogram (ECHO) with 64% having evidence of right atrial systolic collapse and 58% with early diastolic right ventricular collapse. The average time-to-diagnosis with POCUS was 5.9 h compared to > 12 h with other imaging including departmental ECHO. Those who had the PCE identified by POCUS had an average time-to-pericardiocentesis of 28.1 h compared to > 48 h with other diagnostic modalities. Conclusion POCUS expedites the diagnosis of symptomatic PCE given its non-specific clinical findings which, in turn, may accelerate the time-to-intervention.

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