Intercalation of the Microbial Biopolymers Welan Gum and EPS I into Layered Double Hydroxides

2012 ◽  
Vol 67 (5) ◽  
pp. 479-487 ◽  
Author(s):  
Johann Plank ◽  
Serina Ng ◽  
Sebastian Foraita
Keyword(s):  
Layered Double Hydroxides ◽  
Xanthan Gum ◽  
Bacillus Species ◽  
Reaction Products ◽  
Scanning Calorimetry ◽  
Welan Gum ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Double Hydroxides

Three microbial polysaccharides, namely welan gum, scleroglucan, and EPS I, a novel polysaccharide obtained from a newly isolated bacillus species with structural similarities to xanthan gum, were employed in the fabrication of bio-nanocomposites based on layered double hydroxides (LDH). Synthesis was performed by direct co-precipitation of Zn(NO3)2 and Al(NO3)3 in the polysaccharide solutions at pH ~ 8.5. The reaction products were characterized by powder X-ray diffraction (XRD), elemental and thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning and transmission electron microscopy (SEM and TEM). It was found that welan gum is successfully intercalated into the Zn-Al-LDH structure, giving a d-spacing of 2:38 nm for the interlayer distance, while neutral scleroglucan failed to be intercalated. Instead, this biopolymer was only surface-adsorbed on inorganic CaAl-OH-LDH platelets, as was evidenced by de-washing experiments. These results indicate that the anionic functionality of the polysaccharides presents a main driving force behind their intercalation. In contrast to regular xanthan gum, EPS I was intercalated into the LDH structure to give a sharp X-ray reflection representing a d-spacing of 2:77 nm. This behavior proves that slight modifications of the polysaccharide can greatly improve its intercalation ability.

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).

Synthesis of (Y,Gd)2O3:Eu nanopowder by a novel co-precipitation processing

2004 ◽  
Vol 19 (12) ◽  
pp. 3586-3591 ◽  
Author(s):  
Jiyang Chen ◽  
Ying Shi ◽  
Jianlin Shi
Keyword(s):  
Electron Microscopy ◽  
Ammonium Hydroxide ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Hydrogen Carbonate ◽  
Ammonium Hydrogen ◽  
Intense Luminescence ◽  
Co Precipitation

Nano-sized (Y,Gd)2O3:Eu powders were synthesized by a novel co-precipitation processing in which a mixture of ammonium hydroxide and ammonium hydrogen carbonate was adopted as a complex precipitant. Evolution behaviors of precursors during calcinations were studied by means of thermogravimetry-differential scanning calorimetry-mass spectrum, Fourier transform infrared, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy in detail. Nano-sized (Y,Gd)2O3:Eu powder as prepared possessed a primary grain size of about 30 nm and specific surface area of 38 m2/g after being calcined at 850 °C for 2 h, showing much finer grains and less agglomeration. The as prepared nanopowder shows intense luminescence at 611nm under x-ray or ultraviolet excitation. Transparent (Y,Gd)2O3:Eu ceramics can also be fabricated using this high sinterable nanopowder.

scholarly journals Synthesis of hybrid materials based on layered double hydroxides

2019 ◽  
pp. 4-10
Author(s):  
Olga Nestroinaia ◽  
Oksana Ponomarenko
Keyword(s):  
Hybrid Materials ◽  
Layered Double Hydroxides ◽  
Microwave Method ◽  
Hydrothermal Conditions ◽  
Promising Direction ◽  
X Ray ◽  
Constant Ph ◽  
Co Precipitation ◽  
Double Hydroxides ◽  
Scanning Electron

The use of pesticides adversely affects not only the environment, but also human health. A promising direction in solving this problem is to obtain hybrid materials capable of controlled release of pesticides. Layered double hydroxides (LDHs) can act as a matrix. Layered double hydroxides with intercalated glyphosate anions (MgAl-Gly-LDH) were synthesized by different methods: coprecipitation at constant pH (MgAl-Gly-LDH-c), synthesis under hydrothermal conditions (MgAl-Gly-LDH-ht), microwave method (MgAl-Gly-LDH-mw) and rehydration method (MgAl-Gly-LDH-re). All the synthesized samples were analyzed by X-ray phase analysis (XRD), energy dispersive X-ray spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. It is shown that the methods of co-precipitation and synthesis under hydrothermal conditions are most suitable for the synthesis of hybrid materials. Samples of MgAl-Gly-LDH-ht and MgAl-Gly-LDH-c have a well-crystallized structure, unlike the sample of MgAl-Gly-LDH-re, in which the LDH phase is practically absent.

scholarly journals Kinetic Adsorption of Direct Yellow Onto Zn/Al and Zn/Fe Layered Double Hydroxides

2019 ◽  
Vol 4 (4) ◽  
pp. 101
Author(s):  
Neza Rahayu Palapa ◽  
Bakri Rio Rahayu ◽  
Tarmizi Taher ◽  
Aldes Lesbani ◽  
Risfidian Mohadi
Keyword(s):  
Layered Double Hydroxides ◽  
Kinetic Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order ◽  
Bet Method ◽  
Pseudo Second Order ◽  
Time Variations ◽  
Co Precipitation ◽  
Double Hydroxides

Zn/Al and Zn/Fe layered double hydroxides has successfully synthesized by co-precipitation methods with molar ration 3:1. The samples were characterized using X-Ray Diffraction, Fourier Transform Infrared Spectroscopy and Surface Area using BET method. In this study, Zn/Al and Zn/Fe layered double hydroxides were used to remove direct yellow dye in aqueous solution. The experiments were carried out time variations with the aim of observing the kinetic studies. The results showed that the adsorption of direct yellow onto Zn/Al and Zn/Fe layered double hydroxides based on co-efficient correlation kinetic models more fit using pseudo-second-order than pseudo-first-order.

Synthesis, characterization and catalytic behavior of iron porphyrins immobilized in layered double hydroxides

2002 ◽  
Vol 06 (08) ◽  
pp. 502-513 ◽  
Author(s):  
Matilte Halma ◽  
Fernando Wypych ◽  
Sueli M. Drechsel ◽  
Shirley Nakagaki
Keyword(s):  
Layered Double Hydroxides ◽  
Oxidation Reaction ◽  
X Ray Diffraction ◽  
Catalytic Behavior ◽  
X Ray ◽  
Uv Visible ◽  
Immobilized Compounds ◽  
Co Precipitation ◽  
Double Hydroxides ◽  
Homogeneous Media

We report the synthesis, characterization and catalytic behavior of iron(III) porphyrins immobilized in layered double hydroxides (LDH). A combination of EPR, UV-visible spectroscopy and powder X-ray diffraction (PXRD) was used to characterize the products. Three different procedures were used to perform the immobilization of iron porphyrin: a) adsorption into the LDH powder, b) co-precipitation and c) rehydration of calcined LDH. Several different porphyrins ( Fe ( TSPP ), Fe ( TCPP ), Fe ( TPP ) and Fe ( TDFSPP )) were employed in the study. After characterization, the isolated powders were investigated in the oxidation reaction of cyclohexane by iodosylbenzene and hydrogen peroxide in heterogeneous catalysis in comparison to homogeneous media. Some of these immobilized compounds were very good catalysts for this oxidation reaction, stimulating the future investigation of other substrates.

scholarly journals Synthesis and properties of CaAl-layered double hydroxides of hydrocalumite-type

2014 ◽  
Vol 68 (5) ◽  
Author(s):  
Viktor Tóth ◽  
Mónika Sipiczki ◽  
Attila Pallagi ◽  
Ákos Kukovecz ◽  
Zoltán Kónya ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Structural Information ◽  
Basal Spacing ◽  
Sem Images ◽  
Alumina Production ◽  
X Ray ◽  
Precipitation Procedure ◽  
Ion Contents ◽  
Co Precipitation ◽  
Double Hydroxides

AbstractCaAl-layered double hydroxides (CaAl-LDHs) with various carbonate ion contents are essentially formed in Bayer liquors during the causticisation step in alumina production. Under well-defined conditions hemicarbonate is formed, which is beneficial in the process of retrieving both Al(OH)4− and OH− ions. In the current work, Ca2Al-LDHs with various carbonate contents were prepared by the co-precipitation procedure and the products were dried in different ways. Structural information was obtained by a variety of methods, such as X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Elemental maps were constructed through a combination of SEM images and EDX measurements. The targeted CaAl-hydrocalumites were successfully synthesised. It was found that the method used for drying did not influence the basal spacing although it significantly altered the particle sizes.

scholarly journals Preparation of metallic bismuth by reduction of bismuth formates in ethylene glycol medium

2021 ◽  
Vol 340 ◽  
pp. 01014
Author(s):  
Kseniya V. Mishchenko ◽  
Yurii M. Yukhin
Keyword(s):  
Ethylene Glycol ◽  
Gradual Increase ◽  
Spherical Particles ◽  
Metal Powders ◽  
Reaction Products ◽  
Scanning Calorimetry ◽  
Monoclinic Modification ◽  
X Ray ◽  
Transmission Electron ◽  
Metallic Bismuth

Nano -and microcrystalline bismuth metal powders consisting of spherical particles with a size of 150-250 nm were obtained by reducing bismuth formates in an ethylene glycol medium. The phase composition and morphology of the obtained reaction products were studied by X-ray phase and thermal analysis, differential scanning calorimetry, scanning and transmission electron microscopy. Using Uv-vis, it was shown that a bismuth-ethylene glycol complex is formed with an absorption maximum at 249 nm and an extinction coefficient of 5.7×103 (L mol-1 cm-1) in a solution of chloric acid at 23°C. The concentration of bismuth enhances to 0.018 g L-1 in the ethylene glycol medium with a gradual increase in the temperature to 60°C of the reaction mixture. Thermolysis of bismuth glycolate with a composition of Bi2(OCH2CH2O)3 is accompanied by the formation of metallic bismuth at 190°C, which is oxidized to a monoclinic modification of bismuth oxide when the temperature increases in the air.

scholarly journals Efficient solar heterogeneous photocatalytic degradation of metronidazole using heterojunction semiconductors hybrid nanocomposite, layered double hydroxides

2020 ◽  
Vol 82 (12) ◽  
pp. 2837-2846
Author(s):  
Farid Aoudjit ◽  
Fouzia Touahra ◽  
Lamine Aoudjit ◽  
Ouiza Cherifi ◽  
Djamilla Halliche
Keyword(s):  
Photocatalytic Degradation ◽  
Layered Double Hydroxides ◽  
Environmental Remediation ◽  
Solar Irradiation ◽  
Precipitation Method ◽  
Catalyst Loading ◽  
X Ray ◽  
Constant Ph ◽  
Co Precipitation ◽  
Double Hydroxides

Abstract This study focuses on the synthesis of various nanocomposites with heterojunction structures, MgAl-LDH (LDH = layered double hydroxides) hybrid with semiconductor such as MoO3 and CuO. These solids were synthesized by co-precipitation method at constant pH and have been characterized extensively using atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and transmission electron microscopy-energy dispersive X-ray (TEM-EDX) methods. The catalytic activity of nanocomposites was tested in the photocatalytic degradation under solar irradiation of emerging pollutants as the pharmaceutical metronidazole (MNZ). The experimental parameters, including initial MNZ concentration, the nature of oxide incorporate in the photocatalyst, catalyst loading were explored. All the synthesized samples showed high photocatalytic performances; the highest photocatalysis efficiency was achieved with the photocatalyst dose 1.5 g/L and initial MNZ concentration of 10 mg/L at neutral pH. The photocatalytic experimental results were fitted very well to the Langmuir-Hinshelwood model. From the obtained results the calcined LDH/semiconductors could be efficient for the photocatalytic process under solar irradiation of pharmaceuticals and may contribute in environmental remediation.

Characterization of Al2(WO4)3 Synthesized by Co-Precipitation Method

2014 ◽  
Vol 798-799 ◽  
pp. 85-89 ◽  
Author(s):  
E.S.G. Junior ◽  
P.M . Jardim
Keyword(s):  
Precipitation Method ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Tem Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Co Precipitation ◽  
Alpha Alumina

Al2(WO4)3was synthesized by co-precipitation using Na2WO4and Al (NO3)3as precursors. After drying the precipitate, it was calcined at different temperatures between 500°C and 800°C. The crystallization and degradation temperatures of the samples were evaluated by means of Differential Scanning Calorimetry (DSC), Thermogravimetry (TG) and X-Ray Diffraction (XRD). It was observed that the crystallization starts at around 600°C, however Transmission Electron Microscopy (TEM) analysis showed that at this temperature the sample is partially amorphous. The degradation of the material starts at around 1200°C and at 1400°C the tungsten oxide has almost completely evaporated and the material is transformed mainly in alpha-alumina.

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