Role of Fe in the oxidation of methanol electrocatalyzed by Ni based layered double hydroxides: X-ray spectroscopic and electrochemical studies

RSC Advances ◽  
2016 ◽  
Vol 6 (112) ◽  
pp. 110976-110985 ◽  
Author(s):  
Ylea Vlamidis ◽  
Sonia Fiorilli ◽  
Marco Giorgetti ◽  
Isacco Gualandi ◽  
Erika Scavetta ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Layered Double Hydroxides ◽  
Electrochemical Studies ◽  
X Ray ◽  
Oxidation Of Methanol ◽  
Double Hydroxides

Ni-based LDHs for methanol direct fuel cells: the presence of Fe in the LDH structure enhances Ni activity.

Exploring the role of stearic acid in modified zinc aluminum layered double hydroxides and their acrylonitrile butadiene rubber nanocomposites

2014 ◽  
pp. n/a-n/a ◽  
Author(s):  
Subramani Bhagavatheswaran Eshwaran ◽  
Debdipta Basu ◽  
Sankar Raman Vaikuntam ◽  
Burak Kutlu ◽  
Sven Wiessner ◽  
...  
Keyword(s):  
Stearic Acid ◽  
Layered Double Hydroxides ◽  
Butadiene Rubber ◽  
Acrylonitrile Butadiene Rubber ◽  
Rubber Nanocomposites ◽  
Double Hydroxides

scholarly journals Photocatalytic Degradation of 2,4,6-Trichlorophenol by MgO–MgFe2O4 Derived from Layered Double Hydroxide Structures

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 454 ◽  
Author(s):  
Esthela Ramos-Ramírez ◽  
Francisco Tzompantzi-Morales ◽  
Norma Gutiérrez-Ortega ◽  
Héctor G. Mojica-Calvillo ◽  
Julio Castillo-Rodríguez
Keyword(s):  
Photocatalytic Degradation ◽  
Layered Double Hydroxides ◽  
X Ray Diffraction ◽  
Application Study ◽  
Toxic Compounds ◽  
X Ray ◽  
Thermally Activated ◽  
Double Hydroxide ◽  
Double Hydroxides ◽  
Scanning Electron

In recent years, the search for solutions for the treatment of water pollution by toxic compounds such as phenols and chlorophenols has been increasing. Phenols and their derivatives are widely used in the manufacture of pesticides, insecticides, paper, and wood preservers, among other things. Chlorophenols are partially biodegradable but not directly photodegradable by sunlight and are extremely toxic—especially 2,4,6-trichlorophenol, which is considered to be potentially carcinogenic. As a viable proposal to be applied in the treatment of water contaminated with 2,4,6-trichlorophenol, this paper presents an application study of the thermally activated Mg/Fe layered double hydroxides as photocatalysts for the mineralization of this contaminant. Activated Mg/Fe layered double hydroxides were characterized by X-ray diffraction, thermal analysis, N2 physisorption, and scanning electron microscopy with X-ray dispersive energy. The results of the photocatalytic degradation of 2,4,6-trichlorophenol in aqueous solution showed good photocatalytic activity, with an efficiency of degradation of up to 93% and mineralization of 82%; degradation values which are higher than that of TiO2-P25, which only reached 18% degradation. The degradation capacity is attributed to the structure of the MgO–MgFe2O4 oxides derived from double laminate hydroxide Mg/Fe. A path of degradation based on a mechanism of superoxide and hollow radicals is proposed.

scholarly journals Screening Different Divalent and Trivalent Metals Containing Binary and Ternary Layered Double Hydroxides for Optimum Phosphate Uptake

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sattam Fahad Almojil ◽  
Mohamed Abdelhalim Othman
Keyword(s):  
Layered Double Hydroxides ◽  
Phosphate Uptake ◽  
Synergistic Effects ◽  
Bet Surface Area ◽  
Primary Role ◽  
Specific Element ◽  
Phosphate Ion ◽  
Sorbent Materials ◽  
Double Hydroxides

Abstract The elements constituting a layered double hydroxides material provide many alternatives for its optimization. Ten different layered double hydroxides materials with various combinations of Ni, Cu, Zn, Al, Cr, and Fe elements were studied as sorbent materials for phosphate ion. The type of element used in the layered double hydroxides affected the uptake capacity of phosphate. The influence of a specific element alone was not the primary role of enhancing the sorption performance of phosphate ion on the LDHs material. However, using specific two or three elements together is the key to achieve the best result due to synergistic effects. BET surface area of the sorbent showed no correlation with phosphate uptake. From the examined materials, Four layered double hydroxides of Cu-Zn-Cr, Zn-Cr, Ni-Al, and Cu-Ni-Cr showed high phosphate sorption capability. Sorption equilibrium isotherm, reaction kinetics, and desorption of phosphate from the sorbent materials were also investigated.

scholarly journals Potential Sustainable Slow-Release Fertilizers Obtained by Mechanochemical Activation of MgAl and MgFe Layered Double Hydroxides and K2HPO4

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 183 ◽  
Author(s):  
Roger Borges ◽  
Fernando Wypych ◽  
Elodie Petit ◽  
Claude Forano ◽  
Vanessa Prevot
Keyword(s):  
Layered Double Hydroxides ◽  
Slow Release ◽  
Mechanochemical Activation ◽  
Molar Ratio ◽  
X Ray ◽  
Dipotassium Hydrogen Phosphate ◽  
Before And After ◽  
Noticeable Improvement ◽  
Slow Release Fertilizers ◽  
Double Hydroxides

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg2Al-CO3 or Mg2Fe-CO3 layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K2HPO4). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inorganic composites before and after release experiments combined X-Ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The best release profile (<75% in 28 days and at least 75% release) was obtained for MgAl/K2HPO4 (9 h milling, 2:1 molar ratio, MR). Compared to readily used K2HPO4, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K2HPO4 and MgFe/K2HPO4 composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K2HPO4 composites leads to a noticeable improvement of P release properties.

scholarly journals High efficient photocatalytic activity of Zn-Al-Ti layered double hydroxides nanocomposite

2018 ◽  
Vol 149 ◽  
pp. 01087 ◽  
Author(s):  
F. Amor ◽  
A. Diouri ◽  
I. Ellouzi ◽  
F. Ouanji ◽  
M. Kacimi
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Uv Irradiation ◽  
Layered Double Hydroxides ◽  
Removal Rate ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
High Efficient ◽  
Double Hydroxides

This work establishes a simple method for synthesising layered double hydroxides (LDHs) powders with coprecipitation. The characteristics of the samples were investigated y X-ray diffraction (XRD), scanning electron microscopy (SEM) and spectrophotometer UV–Vis (DRS). Non-uniform distribution was shown for LDHs samples by SEM. Photocatalytic efficiencies were tested using methylene blue (MB) dye as a model contaminant under UV irradiation. In particular, Zn–Al-Ti LDH exhibited an excellent performance towards MB degradation compared with commercial TiO2 nanoparticles. Methylene blue removal percentage was reached at almost 100%, whereas commercial TiO2 reached a removal rate of only 66% under the same conditions within 20 min. The aim of the current work is to prepare Zn-Al-Ti layered double hydroxides nanocomposite and to evaluate their photocatalytic activity in the removal of methylene blue under UV irradiation.

scholarly journals Designing Magnetic Layered Double Hydroxides and Two-Dimensional Magnetic Nano-Nets of Cobalt Ferrite through a Novel Approach

2018 ◽  
Vol 8 (11) ◽  
pp. 2099 ◽  
Author(s):  
Osama Saber ◽  
Abdullah Aljaafari ◽  
Sarah Asiri ◽  
Khalid Batoo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Layered Double Hydroxides ◽  
Cobalt Ferrite ◽  
High Coercivity ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Double Hydroxides

The present study has a dual aim of supporting magnetic nanoparticles over the nanolayers of LDHs and designing two-dimensional magnetic nano-nets of cobalt ferrite. In this trend, nanoparticles of CoFe2O4 were prepared and supported by Co-Fe LDH through urea hydrolysis. The nanolayered structures of Co-Fe LDH were confirmed by X-ray diffraction, energy-dispersive X-ray spectrometry, FT-IR spectra, thermal analyses, and transmission electron microscopy. In addition, they indicated that 13.2% CoFe2O4 were supported over Co-Fe LDH. Transformation of the nanolayered structures of Co-Fe LDH to nano-nets was achieved by the catalytic effect of the supported CoFe2O4 nanoparticles through solvent thermal technique. X-ray diffraction patterns and transmission electron microscopy images confirmed the transformation of the supported Co-Fe LDH to nano-nets of cobalt ferrite. In order to indicate the effect of the LDH for designing the nano-nets, nanoparticles of cobalt ferrite were prepared by the same technique without LDH. The magnetic behavior of the nano-nets and the supported Co-Fe LDH were measured and compared with the nanoparticles through vibrating sample magnetometer technique. The magnetic parameters indicated that the prepared nano-nets have ferromagnetic behavior and high coercivity. However, the prepared nanoparticles revealed a superparamagnetic state and low coercivity. The experimental results concluded that the incorporation of nanoparticles with nanowires into nano-net structures has been found to be an efficient way to improve their magnetic properties and prevent their agglomerations. Finally, layered double hydroxides are an important source for constructing magnetic nanolayered structures and nano-nets.

scholarly journals Gas-Phase Hydrogenation of Furfural to Furfuryl Alcohol over Cu-ZnO-Al2O3 Catalysts Prepared from Layered Double Hydroxides

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 486
Author(s):  
Guillermo R. Bertolini ◽  
Carmen P. Jiménez-Gómez ◽  
Juan Antonio Cecilia ◽  
Pedro Maireles-Torres
Keyword(s):  
Gas Phase ◽  
Aging Time ◽  
Layered Double Hydroxides ◽  
Furfuryl Alcohol ◽  
Precipitation Method ◽  
Molar Ratio ◽  
X Ray ◽  
General Chemical ◽  
Co Precipitation ◽  
Double Hydroxides

Several layered double hydroxides (LDHs) with general chemical composition (Cu,Zn)1−xAlx(OH)2(CO3)x/2·mH2O have been synthesized by the co-precipitation method, maintaining a (M2+/M3+) molar ratio of 3, and varying the Cu2+/Zn2+ molar ratio between 0.2 and 6.0. After calcination and reduction steps, Cu/ZnO/Al2O3 catalysts were synthesized. These catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), H2 thermoprogrammed reduction (H2-TPR), N2 adsorption-desorption at −196 °C, N2O titration, X-ray photoelectron miscroscopy (XPS), NH3-thermoprogramed desorption (NH3-TPD) and CO2- thermoprogrammed desorption (CO2-TPD). The characterization data revealed that these catalysts are mainly meso-and macroporous, where Cu, ZnO and Al2O3 are well dispersed. The catalytic results show that these catalysts are active in the gas-phase hydrogenation of furfural, being highly selective to furfuryl alcohol (FOL) and reaching the highest FOL yield for the catalyst with a Cu2+/Zn2+ molar ratio of 1. In an additional study, the influence of the aging time on the synthesis of the LDHs was also evaluated. The catalytic data revealed that the use of shorter aging time in the formation of the LDH has a beneficial effect on the catalytic behavior, since more disordered structures with a higher amount of available Cu sites is obtained, leading to a higher yield towards FOL (71% after 5 h of time-on-stream at 210 °C).

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