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

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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Fumonisin B1 Interaction with Mg-Al and Mg-Fe Layered Double Hydroxides: Removal Efficiency and Mechanisms

Materials ◽

10.3390/ma13194344 ◽

2020 ◽

Vol 13 (19) ◽

pp. 4344

Author(s):

Jakub Matusik ◽

Youjun Deng

Keyword(s):

Adsorption Capacity ◽

Removal Efficiency ◽

Layered Double Hydroxides ◽

Lower Layer ◽

Fumonisin B1 ◽

Xrd Analysis ◽

Layer Charge ◽

Basal Spacing ◽

Co Precipitation ◽

Double Hydroxides

Mycotoxins in feed and food are highly toxic and pose a serious danger even at very low concentrations. The use of bentonites in animal diet can reduce toxin bioavailability. However, some mycotoxins like fumonisin B1 (FB1) form anionic species which excludes the use of negatively charged clays. Layered double hydroxides (LDH) with anion-exchange properties, in theory, can be perfect candidates to adsorb FB1. However, fundamental research on the use of LDH for mycotoxins removal is scarce and incomplete. Thus, the presented study was designed to explore such a possibility. The LDH materials with differing chemistry and layer charge were synthesized by co-precipitation both from metal nitrates and chlorides and were then tested for FB1 removal. XRD, FTIR, XPS, and chemical analysis were used for the LDH characterization and to obtain insight into the removal mechanisms. A higher adsorption capacity was observed for the Mg/Al LDH samples (~0.08–0.15 mol/kg) in comparison to the Mg/Fe LDH samples (~0.05–0.09 mol/kg) with no difference in removal efficiency between Cl and NO3 intercalated LDH. The adsorption capacity increased along with lower layer charge of Mg/Al and was attributed to the lower content of bonded carbonates and the increase of non-polar sites which led to matching between the adsorption domains of LDH with FB1. The FTIR analysis confirmed the negative effect of carbonates which hampered the adsorption at pH 7 and led to the highest adsorption at pH 5 (FB1 content ~15.8 ± 0.75 wt.%). The fast surface adsorption (1–2 min) was dominant and XRD analysis of the basal spacing indicated that no FB1 intercalation occurred in the LDH. The XPS confirmed a strong interaction of FB1 with Mg sites of LDH at pH 5 where the interaction with FB1 carboxylate moieties COO− was confirmed. The research confirmed a high affinity and selectivity of LDH structures towards anionic forms of FB1 mycotoxin.

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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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Synthesis of hybrid materials based on layered double hydroxides

Chemical Bulletin of Kazakh National University ◽

10.15328/cb1025 ◽

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.

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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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Behavior of Layered Double Hydroxides Having Different Divalent Transition Metal Groups

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.563.94 ◽

2014 ◽

Vol 563 ◽

pp. 94-101 ◽

Cited By ~ 2

Author(s):

Mazidah Mamat ◽

Tei Tagg ◽

Wan Mohd Khairul ◽

Mohd Aidil Adhha Abdullah ◽

Norhayati Mohd Tahir ◽

...

Keyword(s):

Weight Loss ◽

Transition Metal ◽

Layered Double Hydroxides ◽

Divalent Cations ◽

Precipitation Method ◽

Basal Spacing ◽

Highest Weight ◽

Ft Ir ◽

Co Precipitation ◽

Double Hydroxides

The layered double hydroxides (LDHs) with different divalent transition metal groups and nitrate as a counter anion were investigated. Three d-block divalent metals namely cobalt (Co), nickel (Ni) and copper (Cu) were selected. The cobalt/aluminium (CoAN)-, nickel/aluminium (NiAN)- and copper/aluminium (CuAN)-layered double hydroxides were successfully synthesized via co-precipitation method. All the obtained LDHs were characterized by PXRD, FT-IR, ICP-OES, CHNS and TGA/DTG analysis. Interestingly, behavior of the LDHs was dependent on the size of divalent cations. PXRD showed the basal spacing decrease in the order NiAN (0.88nm)> CuAN (0.87nm) > CoAN (0.74nm), and in a linear correlation with the increasing radii of the divalent cations. Similar trend is observed for the weight loss of LDHs, where NiAN has the highest weight loss (53%), followed by CuAN (43%) and CoAN (34%). Further elemental analysis showed the content of trivalent metal cations, nitrate anions and water molecules in the LDHs decrease with the increasing radii.

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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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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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Characterization of Chromate-Intercalated Layered Double Hydroxides

Materials Science Forum ◽

10.4028/www.scientific.net/msf.514-516.1541 ◽

2006 ◽

Vol 514-516 ◽

pp. 1541-1545 ◽

Cited By ~ 6

Author(s):

Margarita del Arco ◽

Daniel Carriazo ◽

Cristina Martín ◽

Amalia M. Pérez Grueso ◽

Vicente Rives

Keyword(s):

Layered Double Hydroxides ◽

Thermal Analyses ◽

Basal Spacing ◽

X Ray Diffraction ◽

N2 Adsorption ◽

Exchange Method ◽

X Ray ◽

Ft Ir ◽

Double Hydroxides

PXRD (powder x-ray diffraction), FT-IR (Fourier Transform infrared), N2 adsorption at - 196 °C and TG/DTA (thermogravimetric and differential thermal analyses) techniques have been used for characterisation of MgAl- and ZnAl-CrO4 LDHs, which had been prepared by the ion exchange method from the corresponding chloride LDH (layered double hydroxides) precursors. The results indicates that the oxometalate intercalation in both systems produces interlayer microporosity and a basal spacing of 8.7 Å; This gallery height decreases when the samples are calcined in the temperature range 100-300 °C, due to a grafting process. A larger thermal stability is detected for MgAl-CrO4 sample than for the zinc-containing one.

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Fluorescing Layered Double Hydroxides as Tracer Materials for Particle Injection during Subsurface Water Remediation

ChemEngineering ◽

10.3390/chemengineering4030053 ◽

2020 ◽

Vol 4 (3) ◽

pp. 53

Author(s):

Karen Maria Dietmann ◽

Tobias Linke ◽

Markus Reischer ◽

Vicente Rives

Keyword(s):

Layered Double Hydroxides ◽

Chlorinated Solvents ◽

Cost Effective ◽

Water Remediation ◽

Subsurface Water ◽

Particle Injection ◽

Global Issue ◽

Cost Effective Method ◽

Co Precipitation ◽

Double Hydroxides

Nowadays, the contamination of groundwater and soils by highly hazardous and toxic chlorinated solvents is a global issue. Over the past years, different remediation strategies have been developed, involving injection of reactive solutions and/or particles. However, a major difficulty is the monitoring of injected particles during the injection and after secondary mobilisation by groundwater flow. This study is focussed on the development of directly traceable particles by combining fluorescein with Layered Double Hydroxides (LDHs). We present here the facile and easily tuneable synthesis of fluorescing LDHs (Fluo-LDH) via co-precipitation under supersaturation conditions. Their ability to mimic particle sizes of previously studied reactive LDHs, which proved to be able to adsorb or degrade chlorinated organic solvents from aqueous solutions, was investigated as well. Tests using a novel Optical Image Profiler (OIP) confirmed that the fluorescent LDHs can be easily detected with this tool. Even LDHs with the lowest amount of fluorescent dye were detectable. Together with the use of an OIP, which is capable of exciting the fluorescent material and collecting real-time pictures, this can provide a new, efficient, and cost-effective method for in situ tracing of injected particles in the subsurface.

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