The effect of acid activation and calcination of halloysite on the efficiency and selectivity of Pb(II), Cd(II), Zn(II) and As(V) uptake

Clay Minerals ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 385-394 ◽  
Author(s):  
Paulina Maziarz ◽  
Jakub Matusik
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Structural Changes ◽  
Selective Adsorption ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Acid Activation ◽  
Subsequent Formation ◽  
X Ray ◽  
Mineral Structure

AbstractThe present study investigated the efficiency and mechanisms of aqueous Pb(II), Cd(II), Zn(II) and As(V) adsorption on natural (H), calcined (HC), and acid-activated halloysite (HA). The XRD and FTIR measurements indicated that the aluminosilicate framework was not affected by high-temperature treatment, in contrast to acid activation, which led to structural changes mainly in the tetrahedral sheet. The sorption of cations on H sample was low, though it was most effective for As(V). The X-ray photoelectron spectroscopy results suggested that removal of As(V) might be related to its reduction to As(III) involving oxidation of Fe(II) present in the mineral structure and/or iron minerals. The calcination enhanced halloysite sorption capacity for cations, while the As(V) sorption decreased. This was due to partial dehydroxylation and the subsequent formation of additional active sites. The acid treatment induced selective adsorption of Pb(II).

scholarly journals Pore Modification and Phosphorus Doping Effect on Phosphoric Acid-Activated Fe-N-C for Alkaline Oxygen Reduction Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1519
Author(s):  
Jong Gyeong Kim ◽  
Sunghoon Han ◽  
Chanho Pak
Keyword(s):  
Phosphoric Acid ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Electronic States ◽  
Nitrogen Adsorption ◽  
Reduction Reaction ◽  
Phosphorus Doping ◽  
X Ray ◽  
Precious Metal Catalysts ◽  
Adsorption Desorption

The price and scarcity of platinum has driven up the demand for non-precious metal catalysts such as Fe-N-C. In this study, the effects of phosphoric acid (PA) activation and phosphorus doping were investigated using Fe-N-C catalysts prepared using SBA-15 as a sacrificial template. The physical and structural changes caused by the addition of PA were analyzed by nitrogen adsorption/desorption and X-ray diffraction. Analysis of the electronic states of Fe, N, and P were conducted by X-ray photoelectron spectroscopy. The amount and size of micropores varied depending on the PA content, with changes in pore structure observed using 0.066 g of PA. The electronic states of Fe and N did not change significantly after treatment with PA, and P was mainly found in states bonded to oxygen or carbon. When 0.135 g of PA was introduced per 1 g of silica, a catalytic activity which was increased slightly by 10 mV at −3 mA/cm2 was observed. A change in Fe-N-C stability was also observed through the introduction of PA.

Comparative Study of Time-Dependent PAES and XPS on a Ni/Pd Surface

2017 ◽  
Vol 373 ◽  
pp. 313-316 ◽  
Author(s):  
Samantha Zimnik ◽  
Christian Piochacz ◽  
Sebastian Vohburger ◽  
Christoph Hugenschmidt
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Structural Changes ◽  
Time Dependent ◽  
Xps Analysis ◽  
Time Constants ◽  
X Ray ◽  
Residual Gas ◽  
Rule Out

We report on time-dependent Positron annihilation induced Auger Electron Spectroscopy (PAES) study on 0.5 monolayers (ML) Ni on polycrystalline Pd accompanied by complementary X-ray induced Photoelectron Spectroscopy (XPS). The normalized PAES spectra showed a significant decrease in the Ni intensity and an increase in the Pd intensity as a function of time. To rule out varying influence on the elements e.g. from surface contaminates due to the residual gas, a time-dependent XPS analysis was performed on pure Ni and Pd as well as to analyze the main contaminants C and O. The O fraction was found to be constant within the measurement time and the time constants for C significantly differ from those of Ni and Pd in the PAES data. Consequently, it was concluded that the PAES data show a superposition of C contamination and structural changes at the surface of Ni/Pd.

scholarly journals Copper Containing Glass-Based Bone Adhesives for Orthopaedic Applications: Glass Characterization and Advanced Mechanical Evaluation

2020 ◽  
Author(s):  
Sahar. Mokhtari ◽  
Anthony.W. Wren
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Viscoelastic Behavior ◽  
Polymer Chains ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compression Data

AbstractThis study addresses issues with currently used bone adhesives, by producing novel glass based skeletal adhesives through modification of the base glass composition to include copper (Cu) and by characterizing each glass with respect to structural changes. Bioactive glasses have found applications in fields such as orthopedics and dentistry, where they have been utilized for the restoration of bone and teeth. The present work outlines the formation of flexible organic-inorganic polyacrylic acid (PAA) – glass hybrids, commercial forms are known as glass ionomer cements (GICs). Initial stages of this research will involve characterization of the Cu-glasses, significant to evaluate the properties of the resulting adhesives. Scanning electron microscopy (SEM) of annealed Cu glasses indicates the presence of partial crystallization in the glass. The structural analysis of the glass using Raman suggests the formation of CuO nanocrystals on the surface. X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy (XPS) further confirmed the formation of crystalline CuO phases on the surface of the annealed Cu-glass. The setting reaction was studied using Fourier transform infrared spectroscopy (ATR-FTIR). The mechanical properties of the Cu containing adhesives exhibited gel viscoelastic behavior and enhanced mechanical properties when compared to the control composition. Compression data indicated the Cu glass adhesives were efficient at energy dissipation due to the reversible interactions between CuO nano particles and PAA polymer chains.

scholarly journals Capping Agent Effect on Pd-Supported Nanoparticles in the Hydrogenation of Furfural

Catalysts ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 11 ◽  
Author(s):  
Shahram Alijani ◽  
Sofia Capelli ◽  
Stefano Cattaneo ◽  
Marco Schiavoni ◽  
Claudio Evangelisti ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Catalytic Performance ◽  
Shielding Effect ◽  
Capping Agents ◽  
X Ray ◽  
Supported Nanoparticles ◽  
Liquid Phase Hydrogenation ◽  
Diallyldimethylammonium Chloride ◽  
Transmission Electron

The catalytic performance of a series of 1 wt % Pd/C catalysts prepared by the sol-immobilization method has been studied in the liquid-phase hydrogenation of furfural. The temperature range studied was 25–75 °C, keeping the H2 pressure constant at 5 bar. The effect of the catalyst preparation using different capping agents containing oxygen or nitrogen groups was assessed. Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and poly (diallyldimethylammonium chloride) (PDDA) were chosen. The catalysts were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The characterization data suggest that the different capping agents affected the initial activity of the catalysts by adjusting the available Pd surface sites, without producing a significant change in the Pd particle size. The different activity of the three catalysts followed the trend: PdPVA/C > PdPDDA/C > PdPVP/C. In terms of selectivity to furfuryl alcohol, the opposite trend has been observed: PdPVP/C > PdPDDA/C > PdPVA/C. The different reactivity has been ascribed to the different shielding effect of the three ligands used; they influence the adsorption of the reactant on Pd active sites.

scholarly journals Nitrogen-Doped Sponge Ni Fibers as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaili Zhang ◽  
Xinhui Xia ◽  
Shengjue Deng ◽  
Yu Zhong ◽  
Dong Xie ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
High Performance ◽  
Active Phase ◽  
X Ray ◽  
Highly Active ◽  
N Doping ◽  
Energy Conversion Devices

Abstract Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction (OER) is a particularly significant and challenging target. Herein, we report a 3D porous sponge-like Ni material, prepared by a facile hydrothermal method and consisting of cross-linked micro/nanofibers, as an integrated binder-free OER electrocatalyst. To further enhance the electrocatalytic performance, an N-doping strategy is applied to obtain N-doped sponge Ni (N-SN) for the first time, via NH3 annealing. Due to the combination of the unique conductive sponge structure and N doping, the as-obtained N-SN material shows improved conductivity and a higher number of active sites, resulting in enhanced OER performance and excellent stability. Remarkably, N-SN exhibits a low overpotential of 365 mV at 100 mA cm−2 and an extremely small Tafel slope of 33 mV dec−1, as well as superior long-term stability, outperforming unmodified sponge Ni. Importantly, the combination of X-ray photoelectron spectroscopy and near-edge X-ray adsorption fine structure analyses shows that γ-NiOOH is the surface-active phase for OER. Therefore, the combination of conductive sponge structure and N-doping modification opens a new avenue for fabricating new types of high-performance electrodes with application in electrochemical energy conversion devices.

Structural Changes on Photochromism of Organic-Inorganic Hybrid Materials

1999 ◽  
Vol 604 ◽  
Author(s):  
Keiichi Kuboyama ◽  
Kazumi Matsushige
Keyword(s):  
Fourier Transform ◽  
Tungsten Oxide ◽  
Transition Metal Oxides ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Spectroscopic Measurement ◽  
Inorganic Hybrid ◽  
X Ray ◽  
Oxide Hydrate ◽  
Ft Ir

AbstractSome transition metal oxides are known to exhibit the reversible coloration phenomena. Tungsten oxide is one of such materials and exhibits the photochromism and the electrochromism. It is known that the coloration phenomena in the tungsten oxide hydrate are caused by the redox reaction. We found that the photochromic efficiency became extremely higher by addition of some organic materials to the tungsten oxide hydrate and we have studied the mechanism of such a remarkable photochromic enhancement. In some spectroscopic measurement as FT-IR (Fourier transform infrared spectroscopy) and XPS (X-ray photoelectron spectroscopy), we obtained interesting features as follows. The addition of an organic material leads to reducing the tungsten oxide hydrate to smaller pieces, that is, the surface area of the pieces that can react with the additive increases. Moreover, it was found that specific sites in the additive are oxidized when the sample colors. The fact suggests that the additives having such specific sites can enhance the photochromism of the tungsten oxide hydrate

Pulsed Laser Deposition in a Zinc Alloy Corrosion Study

2003 ◽  
Vol 780 ◽  
Author(s):  
R. Guerrero-Penalva ◽  
M.H. Farías ◽  
L. Cota-Araiza
Keyword(s):  
Pulsed Laser Deposition ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Reactive Element ◽  
General Mechanism ◽  
Zinc Alloy ◽  
Reactive Element Effect ◽  
X Ray

AbstractA significant improvement in corrosion resistance of the protecting oxide of alloys has been observed when adding small amounts of reactive elements, such as yttrium, this effect has been called reactive element effect (REE). The general mechanism of the REE has not been determined yet. In this work, we study a growing of a yttrium oxide film and its interaction with the phases η and α that constitutes the alloy Zn-22Al-2Cu named ZinalcoTM The alloy's surface was coated by a pulsed laser deposition technique. The deposit is controlled and characterized by x-ray photoelectron spectroscopy. The mechanism by which the reactive element produce its effects in this alloy is explained by the preferential interaction among the active sites related to the zinc rich phase and enhancing aluminum movement toward the surface where it is oxidized and the protection film formed.

Synthesis, Structure and Dielectric Properties of Na2SnTeO6

1998 ◽  
Vol 547 ◽  
Author(s):  
J.-H. Park ◽  
P.M. Woodward ◽  
J.B. Parise ◽  
I. Lubomirsky ◽  
O. Stafsudd
Keyword(s):  
Dielectric Constant ◽  
High Pressure ◽  
High Temperature ◽  
Dielectric Properties ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Powder Diffraction Data ◽  
Ambient Conditions ◽  
X Ray ◽  
High Pressure High Temperature

AbstractA new perovskite was recovered from the high pressure-high temperature treatment of the α-TlSbO3 form of Na2SnTeO6 at 7 GPa and 950 °C for 30 minutes. Synchrotron x-ray powder diffraction data show the space group is P21/n with a=5.40361 (5), b=5.46152(5), c=7.69288(7) Å and ß=90.034(3)°. Using disk samples of both polymorphs, the dielectric properties were measured as a function of temperature. At ambient conditions, the perovskite form has a more than 1.5 fold enhancement in dielectric constant compared to the α-TlSbO3 form while the molar volume and the molecular polarizability decrease.

Effect of Phosphorus on the Friction and Wear Characteristics of Cu-Sn-P Alloys

1979 ◽  
Vol 101 (2) ◽  
pp. 201-206 ◽  
Author(s):  
Y. Taga ◽  
K. Nakajima
Keyword(s):  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
Structural Changes ◽  
Surface Concentration ◽  
Wear Characteristics ◽  
X Ray ◽  
The Matrix ◽  
Pin On Disc ◽  
The Coefficient Of Friction ◽  
Friction And Wear Characteristics

The effects of phosphorus on the friction and wear characteristics of Cu-5 at. percent Sn-P alloys containing 1–5 at. percent P were studied using a pin on disc apparatus. The results showed that the decrease in both the coefficient of friction and the rate of wear became conspicuous with the increase in quantity of Cu3P coexisting in the matrix; its amount increases with the content of phosphorus. The structural changes in the surface of the specimen due to heating in a vacuum were observed by using Auger electron spectroscopy and X-ray photoelectron spectroscopy. It was seen that the surface concentration of phosphorus strongly increased after heating at 573K, whereas the diffusion of tin atoms was markedly retarded. It was concluded from these results that the behavior of phosphorus atoms in the surface during sliding played an important role in the friction and wear characteristics of Cu-Sn-P alloys.

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