Hydroxides Of Mg Research Articles

A new material built with alternating Cu sulfide and (Al,Mg) hydroxide molecular sheets: hydrothermal synthesis and selected characteristics.

Two-dimensional materials with new physical phenomena are gaining popularity due to their unique properties. In recent years, a new family of layered compounds inspired by the minerals valleriite and tochilinite which are composed of alternating quasi-atomic sheets of transition metal chalcogenides (sulfides and selenides of Fe, Fe-Cu and other metals) and hydroxides of Mg, Al, Fe, Li, etc., assembled via electrostatic interaction, has arisen as a new synthetic platform for 2D materials. In this work, we synthesized a new promising material composed of alternating quasi two-dimensional sulfide Cu4-xS2 (x = 1-1.5) and hydroxide (Mg1-yAly)(OH)2 (y ∼ 0.25) sheets as multilayer flakes with a lateral size of 1-2 μm and a thickness of several tens of nm. The reliable formation of the material was ensured by an excess of aqueous sodium sulfide along with some quantity of Al salt, which was necessary for the self-assembly of the sulfide and hydroxide sheets driven by their opposite electric charges. A series of samples with varying Al/Mg ratios were examined using TEM, EDS, SAED, XRD, XPS, Raman and UV-vis-NIR spectroscopy. Using the Rietveld refinement procedure, the crystal lattice was determined to resemble the space group P3̄m1 with cell parameters a = b = 3.89 Å and a = b = 3.03 Å for sulfide and hydroxide parts, respectively, and the common parameter c = 12.03 Å. XPS and Raman spectra agree with the chalcocite-like sulfide layers containing Cu+ cations, monosulfide anions and few, if any, S-S bonds. UV-vis-NIR spectra show indirect transitions of 0.8 eV and considerable absorption in the near-infrared region. Thermogravimetry and differential scanning calorimetry studies under an Ar atmosphere suggest a slightly endothermic process and a phase transition at 90 °C accompanied, as suggested by conductivity measurements, by a metal-semiconductor transition; the main destruction with a loss up to 15 wt% occurs at ∼510 °C, due to decomposition of hydroxide layers similar to layered valleriite and tochilinite. The (thermo)electrical data show that, contrary to valleriite, which is an n-type semiconductor with mediocre thermoelectric performance, the proposed material is a heavily doped p-type semiconductor exhibiting good thermoelectric efficiency. The new member of the valleriite family of heterolayered quasi-2D materials demonstrates therefore essentially novel promising properties.

Metal Chalcogenide-Hydroxide Hybrids as an Emerging Family of Two-Dimensional Heterolayered Materials: An Early Review.

Two-dimensional (2D) materials and phenomena attract huge attention in modern science. Herein, we introduce a family of layered materials inspired by the minerals valleriite and tochilinite, which are composed of alternating "incompatible", and often incommensurate, quasi-atomic sheets of transition metal chalcogenide (sulfides and selenides of Fe, Fe-Cu and other metals) and hydroxide of Mg, Al, Fe, Li, etc., stacked via electrostatic interaction rather than van der Waals forces. We survey the data available on the composition and structure of the layered minerals, laboratory syntheses of such materials and the effect of reaction conditions on the phase purity, morphology and composition of the products. The spectroscopic results (Mössbauer, X-ray photoelectron, X-ray absorption, Raman, UV-vis, etc.), physical (electron, magnetic, optical and some others) characteristics, a specificity of thermal behavior of the materials are discussed. The family of superconductors (FeSe)·(Li,Fe)(OH) having a similar layered structure is briefly considered too. Finally, promising research directions and applications of the valleriite-type substances as a new class of prospective multifunctional 2D materials are outlined.

Mixed Oxides Derived from Hydrotalcites Mg/Al Active in the Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol

Herein, a family of Mg/Al hydrotalcites was synthesized as catalytic precursors of MgAlOx mixed oxides. Both hydrotalcites and mixed oxides were characterized and the mixed oxides were tested in the reduction of furfural to yield furfuryl alcohol by MPV reaction using isopropanol as hydrogen donor. Different catalytic parameters were tested, such as the type of alcohol, calcination temperature of the hydrotalcite, and reaction temperature. Furfural and isopropanol were adsorbed on the MgAl-3 catalyst to follow the species adsorbed on the catalyst by FTIR analysis. The results showed that the isopropanol was activated as isopropoxide and furfural changed the adsorption site with increasing temperature but maintaining the h1-conformation. The catalytic performances were associated with the basicity of the catalysts and the deactivation processes have been attributed to the existence of adsorbed species on the surface, mainly due to furfural-derived compounds. The catalysts were reused in three consecutive cycles showing a sharp drop of catalytic activity. To recover the activity, the catalysts were calcined at 500 °C but the activity was only partially recovered. The XPS analysis after reactivation showed that the catalyst surface was modified due to the segregation of hydroxides of Mg and Al.

Effects of the cation ordering in Mg:Al and Zn:Al layered double hydroxides on crystallographic and spectroscopical properties by means of first principles calculations

Layered double hydroxides (LDH) are interesting materials due to their high absorption and catalytic properties. Their applications in environment, agriculture and pharmaceutical fields are becoming widely important. The interlayer and intralayer cation ordering on layered double hydroxides of Mg:Al 2:1 and Zn:Al 2:1 are studied by means of different ordering models at Density Functional Theory level. The cation ordering in LDH is interesting for monitoring the synthesis of these solids and for the applications of LDH, however it is difficult to determine experimentally. We have explored several ordering arrangements of the cation distribution in Mg:Al 2:1 and Zn:Al 2:1 LDH and the effect of these cation arrangements on some crystallographic and spectroscopic properties.

Sorption of U(VI) onto Layered Double Hydroxides of Mg and Al with β-Cyclodextrin from Aqueous Solutions

Sorption of U(VI) onto Layered Double Hydroxides of Mg and Al with β-Cyclodextrin from Aqueous Solutions

Dual approach transformation of human finger and toe nail pruning into MgO/CaO nanoalloy

Interventions of biological entities mediated nanobiotechnological syntheses, in the strive to adapt inexpensive green approaches for constructing materials in the nanodimension for achieving targeted applications with improved performances, are being increasingly preferred. In context, this research article reports to bring into existence applaud able technique, concerning waste utilization for conversion into value added nanomaterial, to manage environmental issues as well as suffice biomedical demands and meet tough challenges from several domains. Pruning nail plates of the fingers and toes, has been a routine affair for the maintenance of personal care, in human civilization. Here we focus the bioengineering of MgO/CaO nanoalloy, by transforming remnant vestigial human finger and toe nail pruning, through dual approach protocols. Obtained yields through direct heat and following chemical treatment protocols were around 61.9% and 62.0%, respectively. Noticeable, quadrangular nanostructural arrangement in sequential array was observed for the MgO/CaO nanoalloy engineered through sol-gel chemical processing prior to thermal decomposition. Chemical treatment of the precursor enabled, formation of large stretches of uniform nanopattern and homogenous distribution to a great extent, from hydroxides of Mg and Ca instead of their salts. The scalable self-assembly with imparted ordered alignment shall inevitably manifest improved nanoalloy activity rather than the randomly distributed nanostuctures attained from direct thermal decomposition of their salts. The multifunctional green MgO/CaO nanoalloy, having tested thermal stability, consisting substantive Ca and Mg, incorporates the dual advantageous of nano MgO and nano CaO, logistically rendering superior benefits. Required characterizations were performed for the investigation of the significant nanostructures, comprising magnificent quadrangular nanobricks, nanorods and nanospheres, derived from the renewable bioresource.

Adsorption of Hexavalent Chromium on Granular Activated Carbon fortified with a layered double hydroxide of Mg and Fe in aqueous solutions

Adsorption of Hexavalent Chromium on Granular Activated Carbon fortified with a layered double hydroxide of Mg and Fe in aqueous solutions

Use of Layered Double Oxides and Hydroxides of Mg and Al for Removing Dyes from Aqueous Solutions Containing 137Cs, 90Sr, 90Y, and U(VI)

The possibility of removing dyes from aqueous solutions containing 137Cs, 90Sr, 90Y, and U(VI) using layered double oxides (LDOs) and hydroxides (LDHs) of Mg and Al was examined. The use of LDO-Mg-Al allows rapid and efficient pretreatment of radioactive solutions containing Cs and Sr radionuclides to remove dyes for the subsequent recovery of Cs and Sr with other selective sorbents. The use of LDO-Mg-Al, LDH-Mg-Al-OH, and LDH-Mg-Al-CD (CD is β-cyclodextrin) allows simultaneous removal from aqueous solutions of UO2(NO3)2 (initial concentration 90%).

Compared arsenic removal from aqueous solutions by synthetic mixed oxides and modified natural zeolites

Layered Double Hydroxides of Mg–Al–Fe and their mixed metallic oxides of high specific surface area were synthesized by the coprecipitation method. A natural zeolite from a regional quarry with high clinoptilolite content was conditioned and modified. Initially, an acid treatment was applied and subsequently Fe(III) was incorporated by the wet impregnation method. Then the prepared solid materials were characterized by XRD, N2 adsorption–desorption at 77 K, SEM, DRS UV–Vis, and MP-AES to determine their physicochemical properties. Finally, the solid materials were evaluated as adsorbents for arsenic removal in water. The tracking of As and its species concentration at trace levels was carried out by cathodic stripping Square-wave voltammetry, which has proved to be a highly selective and sensitive electrochemical method. High levels of effectiveness in terms of removal were achieved, particularly with the natural zeolites and mixed oxides of highest iron content.

Сорбция U(VI) на слоистых двойных гидроксидах Mg и Al, содержащих β-циклодекстрин, из водных растворов

Сорбция U(VI) на слоистых двойных гидроксидах Mg и Al, содержащих β-циклодекстрин, из водных растворов

Packed hybrids of gold nanoparticles and layered double hydroxide nanosheets for microextraction of triazine herbicides from maize.

This work describes a nanohybrid material consisting of gold nanoparticles (AuNPs) and nanosheets of layered double hydroxides (NLDHs) of Mg(II) and Al(III). Mono-disperse AuNPs were immobilized on the surface of the LDHs via Au-O bonding. The nanohybrid sorbent was packed in an organic filter along with a syringe and applied to the microextraction of triazine herbicides with the help of an injection pump. The collected hexane eluate was concentrated and directly injected into a HPLC column for quantification. The effects of the amount of Au/LDH nanohydrobrids, type, flow rate, volume of washing and eluting solvent were optimized. The method was validated by detecting four triazine herbicides (prometryn, atrazine, terbumeton and secbumeton) in spiked maize. The limits of detection range between 35 and 108pgg-1. The relative standard deviations range from 1.0-6.9% for repeatability and 4.6-7.8% for reproducibility (for n = 5). Graphical abstract Schematic presentation of a nanohybrid material consisting of gold nanoparticles and nanosheets of layered double hydroxides of Mg(II) and Al(III) (Au/LDH) for use as an adsorbent for microextraction in a packed syringe. Organic filter heads were used as the container of Au/LDHs nanohybrids, and were connected with the syringes installed on the injection pump for the semi-automatic microextraction and preconcentration of triazines in maize.

Sorption of U(VI) onto layered double hydroxides and oxides of Mg and Al, prepared using microwave radiation

Layered double hydroxides of Mg and Al, containing CО32– ions in the interlayer space (LDH-Mg-Al-CО3), and layered double oxides of Mg and Al (LDO-Mg-Al) were prepared using microwave radiation (MWR). The use of MWR allows not only acceleration of the synthesis of both LDH and LDO, but also preparation of compounds with high kinetic characteristics of the U(VI) sorption. The degree of U(VI) sorption (α) from 10–2 M aqueous U(VI) solutions at a sorption time of 4 h and V/m = 50 mL g–1 exceeds 99.0%. In sorption from more concentrated (10–1 M) aqueous U(VI) solutions under similar conditions, α on all the samples does not exceed 37.5%.

Syntheses of Mg–Al–NO3layered double hydroxides with high crystallinity in the presence of amines

In the present work, layered double hydroxides of Mg–Al were synthesized with nitrate interlayer anions in the presence of different types of amines such as ethylenediamine, dimethylamine, and trimethylamine, without a N2atmosphere, from a homogeneous solution using the coprecipitation method. The concentration of the different types of amines and pH of the solution were adjusted to produce high-purity and -crystallinity samples. The structure and morphology of layered double hydroxides were characterized and investigated by powder X-ray Diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and thermogravimetric analysis techniques. The analyses showed that with increasing amine concentration, both crystallinity and purity of the samples increase at pH 10.5.

Elemental determination of foulings developed in nanofiltration of synthesized liquid low-level radioactive wastes: an LA-ICP-MS study

Herein, we adopted means of LA-ICP-MS to determine the element composition of fouling developed in the end of 24 h filtration of synthesized low-level radioactive liquid. Our experiment results showed that cations possessing identical charges would deposit together, while observed low mass recoveries of Cu, Fe, and Ag ions suggested they have deposited deep in membranes than others. It was therefore speculated that fouling developed might be attributed to the formation of precipitate of high affinity transition metal oxides such as ferric hydroxides and low solubility element such as the hydroxides of Mg and Ca ions.

ChemInform Abstract: One‐Step Bulk Synthesis of Stable, Near Unit‐Cell Sized Oxide Nanoparticles and Nanoparticle Blends Using KO2.

AbstractBulk quantities of nm‐sized oxides or hydroxides of Mg, Y, Ti, Mn, Fe, Co, Ni, Cu, Zn, Sn, Tl, Pb, and Ce, and nanoparticulate blends of the lithium cathode material LiCoO2, the multiferroic compound BiMnO3+δ, and the superconducting YBa2Cu3O7‐γ are prepared from aqueous solutions of sulfates, chlorides, acetates, or nitrates and a 2‐fold molar excess of KO2 (pH 7, <90% yields).

One-step bulk synthesis of stable, near unit-cell sized oxide nanoparticles and nanoparticle blends using KO2.

Presented here is a novel one-step synthesis of oxide or hydroxide nanoparticles using, for the first time, potassium superoxide (KO2). This work demonstrates that the reaction of KO2 with different salt solutions produces grams of stable, near unit-cell sized nanoparticles. This new synthetic technique is applied to representative elements from across the periodic table to rapidly produce nanometer sized oxides or hydroxides of Mg, Al, Y, Ti, Mn, Fe, Co, Ni, Cu, Zn, Sn, Tl, Pb, and Ce. This technique is also used to produce blends of nanoparticles, demonstrating the ability to prepare complex materials such as nanoparticulate blends of a lithium cathode material (LiCoO2), the multiferroic compound (BiMnO(3+δ)), and the superconducting YBa2Cu3O(7-γ).

Sorption of 60Co from aqueous solutions on layered double hydroxides of Mg, Al, and Nd

Sorption of U(VI) from aqueous solutions of various compositions on layered double hydroxides (LDHs) of Mg, Al, and Nd, and also on layered double oxides (LDOs) of Mg and Al was studied. Experiments on sorption of UO22+ carbonate complexes from aqueous solution on LDO-Mg-Al showed that [UO2(CO3)3]4− ions are weakly captured by LDH-Mg-Al formed by contact of LDO-Mg-Al with water. With an increase in the uranium concentration in solution, Kd of U(VI) decreases. For 3.3 × 10−3 M [UO2(CO3)3]4− solutions, after 24-h contact of the solid and liquid phases, the distribution coefficients do not exceed 1.0 ml g−1 at V/m = 50 ml g−1. From aqueous nitrate solutions, U(VI) is sorbed on LDH-Mg-Al-NO3 poorly: Kd of U(VI) does not exceed 1.0 ml g−1 at 24-h contact of the solid and liquid phases and V/m = 50 ml g−1. At the same time, U(VI) is efficiently sorbed from aqueous 10−3 M UO2(NO3)2 solutions on LDH-Mg-Al and LDH-Mg-Nd with CO32− and OH− ions in the interlayer space. After 15-min contact of the solid and liquid phases, Kd of U(VI) exceeds 5 × 103 ml g−1. With an increase in the UO22+ concentration to 10−1 M, Kd of U(VI) decreases considerably, becoming lower than 25 ml g−1, but increases to ∼150 ml g−1 with an increase in the contact time of the solid and liquid phases to 24 h. The effect of the Na+, Ca2+, Cl−, and SO42− ions and of pH of the initial solution on the U(VI) sorption from aqueous UO2(NO3)2 solutions on LDH-Mg-Al-CO3 was examined.

Effect of complexing anions on sorption of U(VI), 90Sr, and 90Y from aqueous solutions on layered double hydroxides of Mg, Al, and Nd

Sorption of 90Sr and 90Y from aqueous solutions on Mg-Al and Mg-Nd layered double hydroxides (LDHs) in various forms was studied. The distribution coefficients Kd of U(VI) and 90Sr on LDH-Mg-Al-EDTA are 100–120 ml g−1 in 15 min of contact of the solid and liquid phases at V/m = 50 ml g−1. At the same time, under similar conditions, U(VI) and 90Sr are not sorbed from aqueous solutions on LDH-Mg-Al-C2O4. The sorption of U(VI) from aqueous solutions containing H2EDTA2−, C2O42−, and CO32− on LDH-Mg-Nd-CO3 and LDH-Mg-Al-CO3 strongly depends on the concentration of the complexing anions in the solution. In particular, for 10−3 M aqueous UO22+ solutions, with an increase in [C2O42−] from 10−3 to 5 × 10−2 M, Kd of U(VI) decreases from >5 × 103 to 70 ml g−1 for LDH-Mg-Al-CO3 and from 170 to ∼0 ml g−1 for LDH-Mg-Nd-CO3. In the presence of 10−3 to 5 × 10−2 M CO32− in aqueous solution, U(VI) is not noticeably sorbed on LDH-Mg-Nd-CO3 (Kd does not exceed 16 ml g−1 at V/m = 50 ml g−1), and on LDH-Mg-Al-CO3 the sorption sharply decreases (Kd decreases from >5 × 103 to ∼0 ml g−1 at V/m = 50 ml g−1). The presence of complexing anions in the solution does not appreciably affect the 90Sr sorption, but noticeably affects the 90Y sorption. With an increase in their concentration, Kd of 90Y appreciably decreases. The effect exerted by Sr2+ ions on the sorption of microamounts of U(VI) and by UO22+ ions on the sorption of microamounts of 90Sr and 90Y from aqueous solutions on LDH-Mg-Nd-CO3 was also examined.

Calcined Mg–Al Layered Double Hydroxides for Uptake of Trace Levels of Bromate from Aqueous Solution

Layered double hydroxides of Mg and Al (Mg–Al LDH) were synthesized with OH–, Cl–, or CO32– as charge compensating anions. The materials were calcined at 500 °C in air. The bromate uptakes of calcined and uncalcined LDH materials were investigated from 0.78 μmol/dm3 bromate solution. Results show that uncalcined LDH exhibited no bromate uptake, although calcined LDH exhibited bromate uptake: the initial bromate concentration of 0.78 μmol/dm3 decreased to less than 0.078 μmol/dm3, the maximum contaminant level established for bromate in drinking water. The rate of bromate uptake of calcined LDH was slow to attain equilibrium in 48 h. The bromate uptake data of calcined LDH agreed well with the Freundlich model.

Structure and Composition of the Layered Double Hydroxides of Mg and Fe: Implications for Anion‐Exchange Reactions

AbstractPartial cation exchange of Mg2+ ions with Fe3+ ions employing solid Mg(OH)2 as precursor yielded an ordered layered double hydroxide of Mg and Fe in the presence of carbonate anions. Structure refinement revealed that the compound adopts the polytype structure 3R1 (space group R$\bar {3}$m, a = 3.108 Å, c = 23.08 Å) and does not show any signs of cation order. It crystallizes with a unique cation ratio of [Mg]/[Fe] = 4. At this ratio, the compound shows a single sharp absorption in its electronic spectrum at 280 nm. Attempts to prepare the LDH with a higher Fe content resulted in the phase separation of excess Fe into X‐ray amorphous binary compounds, the existence of which can be discerned only by the appearance of absorptions at λ > 350 nm, a characteristic of oxide–hydroxides of Fe3+. The nitrate‐containing compound also forms with a similarly low Fe content. At this composition, the compound does not exhibit any anion‐exchange properties as the nitrate ions intercalated in layered hydroxides of low layer charge are not labile. This explains the paucity of information on anion‐exchange reactions of layered double hydroxides of Mg and Fe.