Intercalated Layered Double Hydroxides Research Articles

Electroplating wastewater treatment by in-situ formation of organic anions and inorganic anions intercalated layered double hydroxides

The electroplating wastewater containing various metal ions was treated by adding sodium dodecyl benzene sulfonate (SDBS) and regulating pH value, and the resulting precipitates were characterized by X-ray diffraction (XRD). The results showed that organic anions intercalated layered double hydroxides (OLDHs) and inorganic anions intercalated layered double hydroxides (ILDHs) were in-situ formed to remove heavy metals during the treatment process. In order to reveal the formation mechanism of the precipitates, SDB− intercalated Ni–Fe OLDHs, NO3− intercalated Ni–Fe ILDHs and Fe3+-DBS complexes were synthsized by co-precipitation at various pH values for comparison. These samples were characterized by XRD, Fourier Transform infrared (FTIR), element analysis as well as the aqueous residual concentrations of Ni2+ and Fe3+ were detected. The results showed that OLDHs with good crystal structures can be formed as pH≤7, while ILDHs began to form at pH = 8. When pH < 7, complexes of Fe3+ and organic anions with the ordered layered structure were formed firstly, and then with increase in pH value, Ni2+ inserted into the solid complex and the OLDHs began to form. However, Ni–Fe ILDHs were not formed when pH ≤ 7. The Ksp (Solubility Product Constant) of OLDHs was calculated to be 3.24 × 10−19 and that of ILDHs was 2.98 × 10−18 at pH = 8, which suggested that OLDHs might be easier to form than ILDHs. The formation process of ILDHs and OLDHs were also simulated through MINTEQ software, and the simulation output verified that OLDHs could be easier to form than ILDHs at pH ≤ 7. Information from this study provides a theoretical basis for effective in-situ formation of OLDHs in wastewater treatment.

Polyoxometalate Intercalated Layered Double Hydroxide for Degradation of Procion Red

Polyoxometalate Intercalated Layered Double Hydroxide for Degradation of Procion Red

An effective strategy for removing tetracycline from water: Enhanced adsorption reliability and capacity by tyrosine modified layered hydroxides

The discharge of tetracycline (TCs) antibiotics into the natural environment poses a serious threat to human beings. In the removal of antibiotics by adsorption method, both increase of adsorption capacity and enhancement of adsorption reliability should be considered. In this study, tyrosine intercalated layered double hydroxide (Tyr@LDH) was prepared by a one-step method and characterized by XRD, FT-IR, and SEM. Adsorption kinetics and isotherms studies revealed that compared with LDHs, the adsorption of TC by Tyr@LDH was a multi-layer adsorption process, with more adsorption sites and larger adsorption capacity. Thermodynamic experiments showed that increasing temperature was beneficial to TC adsorption, indicating adsorption was an endothermic process. In the results of the molecular dynamics study, TC molecules entered the interlayer of LDHs by hydrophobic interaction, and possessed strong interactions with Tyr molecules by electron donor and acceptor, hydrogen bonding, and electrostatic interaction. The antibacterial experiments showed that the inhibition zone of Tyr@LDH was smaller than that of LDHs, indicating that with the presence of Tyr, TC molecules were adsorbed reliably. pH, coexisting ions, and recycle experiments proved that 1-Tyr@LDH had reliable adsorption for TC and stability in complex environments. Overall, Tyr@LDH material was expected to be an adsorbent with good adsorption efficiency and reliable adsorption performance for the treatment of TC from the environment.

Ultrafast and Highly Selective Extraction of Uranium from Seawater by Salicylaldoxime Intercalated Layered Double Hydroxide

Ultrafast and Highly Selective Extraction of Uranium from Seawater by Salicylaldoxime Intercalated Layered Double Hydroxide

Scavenging of U(VI) from Impregnated Water at Uranium Tailings Repository by Tripolyphosphate Intercalated Layered Double Hydroxides

The impregnated water at a uranium tailings repository has characteristics that its uranium concentration is low and it contains many other interfering ions. In order to develop an efficient adsorb...

Multi‐Anion Intercalated Layered Double Hydroxide Nanosheet‐Assembled Hollow Nanoprisms with Improved Pseudocapacitive and Electrocatalytic Properties

Electrochemically active hollow nanostructured materials hold great promise in diverse energy conversion and storage applications, however, intricate synthesis steps and poor control over compositions and morphologies have limited the realization of delicate hollow structures with advanced functional properties. In this study, we demonstrate a one-step wet-chemical strategy for co-engineering the hollow nanostructure and anion intercalation of nickel cobalt layered double hydroxide (NiCo-LDH) to attain highly electrochemical active energy conversion and storage functionalities. Self-templated pseudomorphic transformation of cobalt acetate hydroxide solid nanoprisms using nickel nitrate leads to the construction of well-defined NiCo-LDH hollow nanoprisms (HNPs) with multi-anion intercalation. The unique hierarchical nanosheet-assembled hollow structure and efficiently expanded interlayer spacing offer an increased surface area and exposure of active sites, reduced mass and charge transfer resistance, and enhanced stability of the materials. This leads to a significant improvement in the pseudocapacitive and electrocatalytic properties of NiCo-LDH HNP with respect to specific capacitance, rate and cycling performance, and OER overpotential, outperforming most of the recently reported NiCo-based materials. This work establishes the potential of manipulating sacrificial template transformation for the design and fabrication of novel classes of functional materials with well-defined nanostructures for electrochemical applications and beyond.

Biological Evolution of New Intercalated Layered Double Hydroxides: Anticancer, Antibacterial and Photocatalytic Studies

AbstractIn this work, we have synthesized a novel sodium‐3‐nitrobenzenesulfonate (SNBS) of organic moiety intercalated into Zn−Al layered double hydroxide nanoflakes (ZANF) via facile hydrothermal method. The structure, optical property, morphology, size and surface area of the as‐synthesized intercalated Zn−Al nanoflakes (i‐ZANF) were characterized by various techniques. The i‐ZANF was utilized as an anti‐cancer agent against MCF‐7 cell lines. The IC50 value of synthesized i‐ZANF against MCF‐7 cancer cell was found to be 30 μg/mL. Antibacterial activity against noxious bacteria such as, methicillin resistant staphylococcus areus and Acinetobacter baumannii has been examined. Photocatalytic activity of i‐ZANF was evaluated by using methylene blue (MB) as a toxic environmental pollutant. The obtained results showed that the i‐ZANF has notable antibacterial and anticancer activity, along with excellent photocatalytic degradation efficiency (91.2% within 105 min). Hence, it can be proposed that the i‐ZANF with multifunctional applications has been developed to expand as large potential window for anticancer agents, antibaterial and photocatalytic field in upcoming days.

Interlayer Structures and Dynamics of Arsenate and Arsenite Intercalated Layered Double Hydroxides: A First Principles Study

In this study, by using first principles simulation techniques, we explored the basal spacings, interlayer structures, and dynamics of arsenite and arsenate intercalated Layered double hydroxides (LDHs). Our results confirm that the basal spacings of NO3−-LDHs increase with layer charge densities. It is found that Arsenic (As) species can enter the gallery spaces of LDHs with a Mg/Al ratio of 2:1 but they cannot enter those with lower charge densities. Interlayer species show layering distributions. All anions form a single layer distribution while water molecules form a single layer distribution at low layer charge density and a double layer distribution at high layer charge densities. H2AsO4− has two orientations in the interlayer regions (i.e., one with its three folds axis normal to the layer sheets and another with its two folds axis normal to the layer sheets), and only the latter is observed for HAsO42−. H2AsO3− orientates in a tilt-lying way. The mobility of water and NO3− increases with the layer charge densities while As species have very low mobility. Our simulations provide microscopic information of As intercalated LDHs, which can be used for further understanding of the structures of oxy-anion intercalated LDHs.

Rational Design of a Polyoxometalate Intercalated Layered Double Hydroxide: Highly Efficient Catalytic Epoxidation of Allylic Alcohols under Mild and Solvent-Free Conditions.

Intercalation catalysts, owing to their modular and accessible gallery and unique interlamellar chemical environment, have shown wide application in various catalytic reactions. However, the poor mass transfer between the active components of the intercalated catalysts and organic substrates is one of the challenges that limit their further application. Herein, we have developed a novel heterogeneous catalyst by intercalating the polyoxometalate (POM) of Na9 LaW10 O36 ⋅32 H2 O (LaW10 ) into layered double hydroxides (LDHs), which have been covalently modified with ionic liquids (ILs). The intercalation catalyst demonstrates high activity and selectivity for the epoxidation of various allylic alcohols in the presence of H2 O2 . For example, trans-2-hexen-1-ol undergoes up to 96 % conversion and 99 % epoxide selectivity at 25 °C in 2.5 h. To the best of our knowledge, the Mg3 Al-ILs-C8 -LaW10 composite material constitutes one of the most efficient heterogeneous catalysts for the epoxidation of allylic alcohols (including the hydrophobic allylic alcohols with long alkyl chains) reported so far.

Back Cover: Rational Design of a Polyoxometalate Intercalated Layered Double Hydroxide: Highly Efficient Catalytic Epoxidation of Allylic Alcohols under Mild and Solvent‐Free Conditions (Chem. Eur. J. 5/2017)

Back Cover: Rational Design of a Polyoxometalate Intercalated Layered Double Hydroxide: Highly Efficient Catalytic Epoxidation of Allylic Alcohols under Mild and Solvent‐Free Conditions (Chem. Eur. J. 5/2017)

Ammonium alcohol polyvinyl phosphate intercalated LDHs/epoxy nanocomposites

To improve the flame retardancy and mechanical properties of epoxy (EP), a novel intercalated layered double hydroxides (ILDHs) were synthesized by a solution intercalation method using ammonium alcohol polyvinyl phosphate as intercalator. The ILDHs were examined by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), energy-dispersive spectrometry and scanning electron microscopy (SEM). The conditions for synthesis of ILDHs have been optimized. Thermogravimetric analysis indicated a good char-forming property of ILDHs. The flame retardancy of epoxy was improved by adding ILDHs. The EP composites containing 30–40 mass% ILDHs passed UL-94V-0 rating. Tensile strength was also enhanced by adding 30–40 mass% ILDHs, which was attributed to the involvement of physical cross-linking network among layered particles and polymer chains. The morphology and structures of residues generated during LOI test were investigated by SEM and FTIR to support a fundamental analysis for the mechanism of char formation. SEM observations of residues of the ILDHs/EP confirmed the formation of an incompact charred layer during combustion, which could inhibit the transmission of heat and mass during combustion. It may be inferred that ILDHs acted as a catalyst for esterification, dehydration and compact char formation of EP system.

Efficient Hg Vapor Capture with Polysulfide Intercalated Layered Double Hydroxides

We report detailed studies showing that the novel layered polysulfide compounds Sx-LDH (Sx2–, polysulfides, x = 2, 4, 5; LDH, Mg–Al layered double hydroxides) can capture efficiently large quantities of mercury (Hg0) vapor. During the adsorption process, the interlayer polysulfides [Sx]2– react with Hg0 through their S–S bond to produce HgS. The structure of Sx-LDH before and after Hg-adsorption was characterized with X-ray diffraction, vibration spectroscopy, and scanning electron microscopy. The presence of adsorbed Hg was verified by weight gain, inductively coupled plasma atomic emission spectroscopy and X-ray photoelectron spectroscopy. Despite their relatively low surface areas, the S2-LDH, S4-LDH, and S5-LDH samples show excellent Hg capture capacities of 4.9 × 105, 7.4 × 105, and 1.0 × 106 μg/g, respectively, corresponding to 50–100% adsorption rates by weight, highlighting the potential of these materials in natural gas purification. The Hg-capture efficiency and mechanism in Sx-LDH are supported...

Preparation and properties of in‐situ polymerized polyurethane/stearate intercalated layer double hydroxide nanocomposites

AbstractThe present work deals with the effect of stearate intercalated layered double hydroxide (St‐LDH) loadings on the morphological, mechanical, thermal, adhesive and flame retardant properties of polyurethane (PU)/St‐LDH nanocomposites prepared by the in situ polymerization method. X‐ray diffraction and transmission electron microscopy studies confirmed that exfoliation takes place at 3 wt% loading followed by intercalation at higher filler loadings in the PU matrix. The exfoliated structure has been further verified by atomic force microscopy. The measurements of stress‐strain, thermogravimetric analysis, dynamic mechanical analysis, lap shear strength and peel strength analysis showed that the nanocomposites containing 3 wt% St‐LDH exhibit excellent improvement in tensile strength (ca 175%) and log storage modulus (ca 14%), while PU/St‐LDH (5 wt%) possesses optimum improvement in glass transition temperature (ca 6 °C), lap shear strength (200%) and peel strength (130%) over neat PU. In addition, the gradual improvements in limiting oxygen index value with St‐LDH loading indicated the higher effectiveness in providing better barrier properties as well as better flame retardant behavior. Copyright © 2012 Society of Chemical Industry

Synthesis and Characterization of Ifosfamide Intercalated Layered Double Hydroxides

Two anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecylbenzensulfonate (SDBS), were intercalated into Mg2Al layered double hydroxides (LDHs) using the anion exchange method. Then an alkylating oxazaphosphorine anticancer agent, ifosfamide (IFO), was intercalated into the surfactant-modified LDHs. The IFO-surfactant-LDHs nanohybrids were characterized by PXRD, FTIR, TEM, and elemental chemical analyses. The in vitro drug release from the nanohybrids is remarkably lower than that from the corresponding physical mixture at pH 7.5. The obtained results show these IFO-surfactant-LDHs nanohybrids can be used as potential anticancer drug controlled release system.

Synthesis and Characterization of Alkyl Polyglycoside Intercalated Layered Double Hydroxides

Nonionic surfactant, alkyl polyglycoside (APG), has been successfully intercalated in the gallery space of Mg-Al layered double hydroxide (LDH) via co-precipitation method. The possible effects of the pH, molar ratios of Mg/Al, and APG amount on the APG intercalated LDH are investigated. Under the optimal conditions, a probably orientation is that APG intercalated with an angle about 50° between APG chains and LDH layers, according to the gallery height of APG-LDHs and size of APG molecule. Thermal behavior shows higher thermal decomposition temperature of APG-LDH than pure APG.

The Synthesis of Mg-Zn-Al LDH and the Sustained-Release Properties of Theophylline Intercalated LDH

Layered double hydroxides (LDHs), consist of cationic brucite-like layers and exchangeable interlayer anions. In this thesis LDHs consist of brucite-like layers of zinc hydroxide, with the exchanging propertity of interlayer anions in hydrotalcites, used Mg/Zn/Al-LDH as precursor to prepare the theophylline intercalation assembly hydrotalcites to obtain supramolecular complex for the first time by co-precipitation under a nitrogen atmosphere, determined the reaction conditions and influential factors of the synthesis of theophylline-pillared hydrotalcites, and tested its sustained-release performance in different media. The product has been characterized by powder X-ray diffraction (XRD), FT-IR spectroscopy, uv-vis spectrophotometer and thermogravimetry-Differential thermal analysis (TG-DTA) . Results demonstrated that : Through co-precipitation intercalation methods, with molar ratio of Mg/Zn/Al/ theophylline being 3:1:1:2, co-precipitation medium pH9, crystallization temperature 80 °C and crystallization time 12h can obtain the clear chemical composition and good crystallization of inorganic - organic hybrid-type drugs hydrotalcites. In addition, according to Pharmacopoeia measured the release rate of theophylline-LDH in the different media including distilled water,0.9%saline,simulated intestinal fluid (pH7.4 phosphate buffer) by UV spectrophotometry, Theophylline pillared hydrotalcite has a certain release in the media above all. And calculated the release of intercalation theophylline, lay the foundation for the further clinical application.

Photocatalytic Performance of Polyoxometallate Intercalated Layered Double Hydroxide

Based on X-ray diffraction results, the gallery height of modified Mg3Al-LDH was expanded to 9.6Å from the original 4.8Å, indicating that the H3PW12O40 was indeed inserted into the hydroxide layers. Moreover, the results of FT-IR spectra proved the Keggin structure of PW11O397- species. The resulting material showed a high activity of degradation of methyl orange in the presence of H2O2 and UV light irradiation.

Molecular Dynamics Simulation on Structure, Hydrogen-Bond and Hydration Properties of Diflunisal Intercalated Layered Double Hydroxides

The supramolecular structure of diflunisal intercalated layered double hydroxides (DIF/LDHs) was modeled by molecular dynamics (MD) methods. Hydrogen bonding, hydration and swelling properties of DIF/LDHs were investigated. The interlayer spacing dc was found to be constant (ca 1.80 nm) when N(subscript w) (the ratio of the numbers of water molecule to DIF) ≤3. The interlayer spacing dc gradually increases as N(subscript w)≥4 and this increase follows the linear equation d(subscript c)=1.2611Nw+13.63. The hydration energy gradually increases as the water content increases. LDHs/DIF hydrates when N(subscript w)≤16 because hydration energy ΔU(subscript H)＜-41.84 kJ•mol^(-1). At N(subscript w)≥24 the hydration of LDHs/DIF does not occur because ΔU(subscript H)＞-41.84 kJ•mol^(-1). Swelling of LDHs/DIF is thus limited in an aqueous environment. The interlayer of DIF/LDHs contains a complex hydrogen bonding network. The hydration of DIF/LDHs occurs as follows: water molecules initially form hydrogen bond with layers and anions. While the anions gradually reach a saturation state and water molecules continue to form hydrogen bonds with the hydroxyls of the layers. The L-W type hydrogen bond gradually substitutes the L-A type hydrogen bond and the anions move to the center of an interlayer and then separate with the layers. Last, a well-ordered structural water layer is formed on the surface hydroxyls of DIF/LDHs.