Synthesis of hybrid materials based on layered double hydroxides

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.

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

Water Science & Technology ◽

10.2166/wst.2020.519 ◽

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.

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

Catalysts ◽

10.3390/catal9050454 ◽

2019 ◽

Vol 9 (5) ◽

pp. 454 ◽

Cited By ~ 5

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.

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

Catalysts ◽

10.3390/catal10050486 ◽

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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Photocatalytic decolourization of methylene blue using [Zn-Al] layered double hydroxides synthesized at different molar cationic ratios

Clay Minerals ◽

10.1180/claymin.2017.052.2.03 ◽

2017 ◽

Vol 52 (2) ◽

pp. 203-215 ◽

Cited By ~ 2

Author(s):

Kaouther Abderrazek ◽

Najoua Frini Srasra ◽

Ezzeddine Srasra

Keyword(s):

Methylene Blue ◽

Photocatalytic Activity ◽

Layered Double Hydroxides ◽

Diffuse Reflectance Spectroscopy ◽

X Ray Diffraction ◽

X Ray ◽

Inductively Coupled ◽

Molar Ratios ◽

Constant Ph ◽

Double Hydroxides

Abstract[Zn-Al] layered double hydroxides (LDH) with cationic molar ratios of R = Zn/Al 1–5 were synthesized by the coprecipitation method at constant pH = 10. The samples synthesized and their derived forms obtained after calcination at 500°C and at 900°C (denoted Zn-Al-R, Zn-Al-R-500 and Zn-Al-R-900, respectively), were characterized by X-ray diffraction (XRD), inductively coupled plasmamass spectrometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, diffuse reflectance spectroscopy and nitrogen physisorption at −196°C. The XRD study showed: (1) the presence of accessory ZnO with the LDH in samples synthesized with R ≥ 3; and (2) the lamellar structure was destroyed at 500°C which made room for a poorly ordered ZnO phase, while calcination at 900°C yielded well crystallized ZnO and ZnAl2O4. The photocatalytic activity of the calcined and the unheated samples was evaluated for the decolourization of methylene blue. The photocatalytic activity was dependent on the cationic ratio R and on the calcination temperature. The sample Zn-Al-3 displayed maximum photocatalytic activity. Calcination at 500 and 900°C improved the photocatalytic activity of LDH synthesized at R = 1 and 2.

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

Science & Technology Indonesia ◽

10.26554/sti.2019.4.4.101-104 ◽

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.

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Undoped and Eu3+ Doped Magnesium-Aluminium Layered Double Hydroxides: Peculiarities of Intercalation of Organic Anions and Investigation of Luminescence Properties

Materials ◽

10.3390/ma12050736 ◽

2019 ◽

Vol 12 (5) ◽

pp. 736 ◽

Cited By ~ 3

Author(s):

Aurelija Smalenskaite ◽

Lina Pavasaryte ◽

Thomas Yang ◽

Aivaras Kareiva

Keyword(s):

Layered Double Hydroxides ◽

Organic Anion ◽

Sol Gel ◽

Xrd Analysis ◽

X Ray Diffraction ◽

X Ray ◽

Organic Guests ◽

Double Hydroxides ◽

Scanning Electron

The Mg3/Al and Mg3/Al0.99Eu0.01 layered double hydroxides (LDHs) were fabricated using a sol-gel chemistry approach and intercalated with different anions through ion exchange procedure. The influence of the origin of organic anion (oxalate, laurate, malonate, succinate, tartrate, benzoate, 1,3,5-benzentricarboxylate (BTC), 4-methylbenzoate (MB), 4-dimethylaminobenzoate (DMB) and 4-biphenylacetonate (BPhAc)) on the evolution of the chemical composition of the inorganic-organic LDHs system has been investigated. The obtained results indicated that the type and arrangement of organic guests between layers of the LDHs influence Eu3+ luminescence in the synthesized different hybrid inorganic–organic matrixes. For the characterization of synthesis products X-ray diffraction (XRD) analysis, infrared (FTIR) spectroscopy, fluorescence spectroscopy (FLS), and scanning electron microscopy (SEM), were used.

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

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424602000634 ◽

2002 ◽

Vol 06 (08) ◽

pp. 502-513 ◽

Cited By ~ 31

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.

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

Zeitschrift für Naturforschung B ◽

10.5560/znb.2012-0081 ◽

2012 ◽

Vol 67 (5) ◽

pp. 479-487 ◽

Cited By ~ 4

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.

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Synthesis and characterisation of alkaline earth-iron(III) double hydroxides

Chemical Papers ◽

10.2478/s11696-011-0079-1 ◽

2011 ◽

Vol 65 (6) ◽

Cited By ~ 9

Author(s):

Mónika Sipiczki ◽

Dávid Srankó ◽

Ákos Kukovecz ◽

Zoltán Kónya ◽

Pál Sipos ◽

...

Keyword(s):

Alkaline Earth ◽

Precipitation Method ◽

Optimum Conditions ◽

Solid Materials ◽

X Ray ◽

Co Precipitation ◽

Double Hydroxides ◽

Instrumental Methods ◽

Elemental Maps ◽

Scanning Electron

AbstractDouble hydroxides containing alkaline earth and iron(III) ions were synthesised by the co-precipitation method. The solid materials obtained were characterised by a range of instrumental methods (powder X-ray diffractometry, thermogravimetry, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, elemental maps, and infrared spectroscopy). It was found that the Ca(II)Fe(III), Mg(II)Fe(III), and Ba(II)Fe(III) double hydroxides had layered structures, while Sr(II)Fe(III) had not. The optimum conditions for synthesis of Ca(II)Fe(III)-layered double hydroxides (materials to be used in further studies) were also elaborated.

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

Chemical Papers ◽

10.2478/s11696-013-0500-z ◽

2014 ◽

Vol 68 (5) ◽

Cited By ~ 12

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.

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