Hydrotalcite Interlayer Research Articles

Effect of poly(AMPS/DMAA/IA/SSS) intercalated Mg/Al layered double hydroxides on reducing fluid loss at 240 °C and improving early strength of oil well cement

Fluid loss agent (FLA) was adopted to reduce the fluid loss of cement paste to ensure the safety of cementing construction. With the increase of exploration depth, FLA applied at high temperatures has been urgently required. To meet the cementing requirements at 240 °C, the FLA with organic/inorganic intercalated microstructure was prepared. Anionic polymer FLA (ADIS) was comprised of 2-acrylamido-2-methylpropane sulfonic Acid (AMPS), N, N-dimethylacrylamide (DMAA), Itaconic acid (IA) and Sodium p-styrene sulfonate (SSS). The organic-inorganic hybrid FLA (MgAl-ADIS-LDH) was prepared via intercalating ADIS into Mg/Al hydrotalcite (MgAl-NO3-LDH) interlayers. The intercalated microstructure was observed by SEM, TG results exhibited that the intercalation of polymer ADIS in MgAl-NO3-LDH enhanced the thermal stability of overall FLA. When applied in cement, the cement with MgAl-ADIS-LDH showed a small water loss of 36 mL at 240 °C. Moreover, the structure avoided the decrease in the compressive strength of hardened cement resulted from traditional polymer FLA. Compared with the cement contains 1.6% bwoc ADIS, the compressive strength of specimen with MgAl-ADIS-LDH increased by 20.5% after cured for 3 days.

One-step synthesis of annual ring-shaped planar nitrogen/sulfur co-doped nanoporous graphene for supercapacitance

Heteroatom-doped nanoporous graphene has great potential as emerging energy storage materials, but the complex synthetic routes and disordered structure limit the improvement of supercapacitance performance. Herein, we develop a one-step synthesis strategy to obtain nitrogen/sulfur doped nanoporous graphene (NS-NG). Graphene oxides absorbed with dyes are burned in a confined interlayer of porous hydrotalcite for preparing NS-NG. Interestingly, the NS-NG retains the morphology of multilayer graphene oxides coated with fiber rods before combustion, so it exhibits the annual ring -shaped structure, larger surface area, and highly porosity. Importantly, the NS-NG not only shows a high specific capacitance of 325 F g−1, and also has a high energy density of 25 Wh kg−1 at a high power density of 1906 W kg−1with an excellent capacity retention of 86% after 10,000 cycles applied in the two-electrode symmetric supercapacitor at a current density of 2 A g−1 in 0.5 M Na2SO4 aqueous solution.

In situ constructed zeolite membranes on rough supports with the assistance of reticulated hydrotalcite interlayer.

Zeolite membranes with unique physical and chemical properties are emerging as attractive candidates for membrane separation. However, defects in the zeolite layer seriously affect their molecular sieving performance. In this study, a novel strategy for preparing compact zeolite membranes on rough supports with the assistance of a reticulated hydrotalcite layer was developed. The reticulated hydrotalcite layer was grown on the inner surface of a 170 mm length ceramic tube by an in situ hydrothermal method, and a NaA zeolite membrane was prepared on this reticulated layer by the microwave-heating method. The hydrotalcite interlayer could not only improve the smoothness and regularity of the surface of the support but also fix the Si/Al active ingredients using its reticulate structure, finally effectively improving the quality and stability of the zeolite layer. The optimal molar ratio of the synthesis solution for the synthesis of the zeolite membrane was 3Na2O : 2SiO2 : Al2O3 : 200H2O. The permeance flux of H2 through the zeolite membrane synthesized under the optimal conditions was high as 0.47 × 10−6 mol m−2 s−1 Pa−1, and its permselectivity for H2 over N2 was 4.7, which was higher than the corresponding Knudsen diffusion coefficient. This study provides a new idea for the preparation of defect-free membranes on rough supports.

Nitrogen-doped nanoporous graphene induced by a multiple confinement strategy for membrane separation of rare earth.

SummaryRare earth separation is still a major challenge in membrane science. Nitrogen-doped nanoporous graphene (NDNG) is a promising material for membrane separation, but it has not yet been tested for rare earth separation, and it is limited by multi-complex synthesis. Herein, we developed a one-step, facile, and scalable approach to synthesize NDNG with tunable pore size and controlled nitrogen content using confinement combustion. Nanoporous hydrotalcite from Zn(NO3)2 is formed between layers of graphene oxide (GO) absorbed with phenylalanine via confinement growth, thus preparing the sandwich hydrotalcite/phenylalanine/GO composites. Subsequently, area-confinement combustion of hydrotalcite nanopores is used to etch graphene nanopores, and the hydrotalcite interlayer as a closed flat nanoreactor induces two-dimensional space confinement doping of planar nitrogen into graphene. The membrane prepared by NDNG achieves separation of Sc3+ from the other rare earth ions with excellent selectivity (∼3.7) through selective electrostatic interactions of pyrrolic-N, and separation selectivity of ∼1.7 for Tm3+/Sm3+.

Enhanced sorption of perfluorooctane sulfonate and perfluorooctanoate by hydrotalcites

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are recalcitrant compounds that are toxic to humans and ecosystems. Hydrotalcite-like compounds have emerged as promising PFOS and PFOA sorbents due to their high anion exchange capacity and high specific surface area. In this study, hydrotalcite (HT) compounds were intercalated with nitrate and carbonate ions (HT-CO 3 and HT-NO 3 ) and their specific surface area and particle aggregate size modified by treatment with acetone (AHT-CO 3 and AHT-NO 3 ). Sorption experiments with AHT-NO 3 indicated that sorption equilibrium was reached faster with PFOS (< 5 min) compared to PFOA (< 20 min), and that sorption capacity for PFOS (1,610.0 mg/g) was substantially higher compared to PFOA (909.0 mg/g). The sorption yields are explained by anion exchange occurring at higher PFOS and PFOA concentrations, along with surface adsorption, and by PFOS having a higher affinity for the HT interlayer. In comparison to AHT-NO 3 , PFOS and PFOA sorption by AHT-CO 3 was slower (equilibration times ≥ 20 min) and the maximum capacities were generally lower, because anion exchange is hindered by the affinity of the carbonate ion for the HT interlayer. As such, surface adsorption dominated across a large PFOS and PFOA concentration range (up to 2,000 mg/L). The presence of non-ionic species (trichloroethylene) did not affect the sorption capacity, while alkaline pH conditions and the presence of other anionic species (dodecyl sulfate) reduced the sorption capacity of AHT compounds towards PFOS and PFOA. Compared to untreated HT compounds, acetone treated HT exhibited improved sorption properties towards PFOA and PFOS removal from groundwater, particularly AHT-CO 3 . Overall, AHT compounds outperform activated carbon sorbents in terms of PFOA and PFOS sorption kinetics and capacities, thus could be promising new sorbents for PFAS removal from contaminated waters. • Acetone-treated hydrotalcites (AHT) show modified physical properties. • Nitrate-intercalated AHT show fast equilibration time (<1 h) towards PFOS and PFOA. • The maximum sorption uptake for PFOS is 1,610 mg/g by nitrate-intercalated AHT. • XPS and other techniques are used to evaluate the sorption mechanism. • Alkaline pH and other anions impact the sorption capacity of PFOS and PFOA by AHT.

Stabilization of Cu-Chlorophyllin by Incorporation into Hydrotalcite Interlayer

Stabilization of Cu-Chlorophyllin by Incorporation into Hydrotalcite Interlayer

Preparation and properties of hierarchical Al–Mg layered double hydroxides as UV resistant hydrotalcite

Anti-ultraviolet Mg–Al hydrotalcite samples (MgAl–P-LDH) with 4-metoxybenzoic acid (PMOBA) ion intercalation were prepared by high temperature reduction method. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Visible absorption spectrophotometry, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry. SEM images indicate that the UV-resistant MgAl–P-LDH had a layered structure. The results of X-ray diffraction analysis showed that the purity of MgAl–P-LDH sample was higher. Compared to MgAl-LDH, the characteristic peak for MgAl–P-LDH shifted towards small angle of 2θ, and it was found that the PMOBA ions have been inserted into the interlayer of MgAl hydrotalcite. The infrared spectra also showed that PMOBA ions were successfully intercalated within Mg–Al hydrotalcite layer. The ultraviolet absorption of MgAl–P-LDH was better than that of PMOBA and MgAl-LDH with the wavelength range of 225–325 nm, and the maximum absorption over 80% was observed.

L–Cysteine/Hydrotalcite Hybrid for Collaborative Removal of Cu(II), Hg(II) and Pb(II) Ions from Aqueous Solutions: Different Metal Ions Require Different Mechanisms

AbstractThe L‐cysteine/hydrotalcite hybrid has been synthesized by incorporating L‐cysteine anion into the interlayer of hydrotalcite. The sample is purposed for the removal of Cu2+, Pb2+ and Hg2+ from aqueous solutions. The structure and morphology of L‐cysteine/hydrotalcite are characterized by XRD, FTIR, SEM and BET. The effects of various physic‐chemical factors such as pH, adsorbent dosage and contact time are investigated. The maximum adsorption capacities of L‐cysteine/ hydrotalcite for Cu2+, Pb2+ and Hg2+ are 157.99, 81.24 and 215.90 mg/g, respectively, which are obviously higher than those of the pristine hydrotalcite. The adsorption kinetics are fitted by the pseudo‐second order model. The adsorption isotherms are well described by the Langmuir equation. As confirmed by XRD and XPS analysis, a mechanism for adsorbed Cu2+ in the form of coordinated complexes and isomorphous substitution is proposed. In contrast, a precipitation mechanism is suggested for adsorbed Hg2+ and Pb2+. The results demonstrate that L‐cysteine/hydrotalcite is a promising adsorbents for efficient elimination toxic metal ions from wastewater.

The Influence of Hydrotalcite Intercalated with Benzoate on UV Stability of Acrylic Coating

It is important to realize that benzoate was intercalated into hydrotalcite (HTC-Bz) by the co-precipitation method. In this case, acrylic coating with 0.5 wt% HTC-Bz was deposited on carbon steel using the spin coating method. Next, the HTC-Bz structure was characterized by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). In fact, an ultraviolet vision spectroscopy (UV-Vis) was used to determine the benzoate content in HTC-Bz, and the UV absorption ability of HTC-Bz. Using electrochemical techniques, water contact angle measurement, and thermal-gravimetric analysis, we compared the protective properties before and after QUV test, hydrophobicity and the thermal stability of acrylic coating containing HTC-Bz. The obtained results showed that HTC-Bz with a plate-like structure was successfully synthesized; benzoate was intercalated into the interlayer of hydrotalcite with a concentration of 28 wt%. Additionally, it was noted that HTC-Bz has an UV absorption peak at 225 nm. In conclusion, the addition of HTC-Bz enhanced the UV stability, hydrophobicity and the thermal stability of acrylic coating.

Chloride and heavy metal binding capacities of hydrotalcite-like phases formed in greener one-part sodium carbonate-activated slag cements

The treatment of industrial solid wastes requires a proper binder that can efficiently solidify and stabilize the harmful containments. Previous studies have shown that the incorporation of calcined dolomite (CD) in the one-part sodium carbonate-activated blast furnace slag binder promotes the formation of hydrotalcite-like phases, which exhibit a potentially high ion-binding capacity. This study investigates the chloride and heavy metals binding capacities of the hydrotalcite-like phases formed in the binder. The results show that this binder has higher resistance to chloride penetration than the Portland cement and other alkali-activated slag pastes. The solidification efficiencies of Pb2+, Cu2+ and Cr3+ ions for the binder with 10% CD dosage are in the range of 66–88%. The hydrotalcite formation mechanism proposed in this work suggests that the carbonate ion-exchange in the interlayer of hydrotalcite reduces the available binding sites, so the binding capacity is mainly attributed to the physical surface adsorption, rather than interlayer ion-exchange. The CO2 emission and energy consumption of this binder are around 80% lower than the PC paste. This study provides a guidance for the production of greener binder for the use in the treatment of industrial solid wastes.

Interkalasi Ion Mefenamat pada Host Mg/Al Hidrotalsit sebagai Rancangan Obat Lepas Lambat

The aim of this study was to intercalate mefenamic ions in the interlayer structure of Mg/Al hydrotalcite and to test the release of mefenamic ion from host hydrotalcite interlays to determine its potential as a slow release drug design. Intercalation of mefenamic ions into interlayer structure of Mg/Al hydrotalcite by ion exchange has been studied. This success intercalation was confirmed by XRD data, diffractogram before and after intercalation showed a shift of d003, d006 and d009. The change of d003 from 8.717 Å to 22.017 Å indicates that the mefenamic ion has entered the interlayers of hydrotalcite. The FTIR analysis confirms that the nitrate ion was successfully replaced by mefenamic ions in the hydrotalcite interlayer. FTIR data indicate the absorption of symmetry and asymmetry of carboxylic groups in 1381 and 1612 cm-1 of the mefenamic ion. Have studied ion exchange kinetics and release of mefenamic ions from hydrotalcite hosts to determine their potential as a slow-release drug design. The result show mefenamic ion can be released from the hydrotalcite host for 6 hours. So that Mg / Al hydrotalcite has the potential to be used in slow release drug design.

Facile preparation of an efficient flame retardant and its application in ethylene vinyl acetate

A novel phosphorus-nitrogen-clay flame retardant (PD-LDH@MF) was prepared via intercalating pentaerythritol diphosphate (PEDP) into MgAl hydrotalcite (LDH) interlayers and then capping melamine resin (MF) on the surface using in-situ copolymerization. The structure, morphology thermal stability and flame retardancy of the PD-LDH@MF material were characterized by various analytic methods. The results revealed that PEDP anions were intercalated successfully into the interlayers of the LDH, and the PEDP-intercalated LDH (PD-LDH) was also encapsulated in MF. The PD-LDH@MF exhibited better compatibility with EVA matrix than the EVA/PD-LDH due to higher hydrophobicity by capping MF on the surface of the PD-LDH particles. The incorporation of the PD-LDH@MF into EVA could improve not only the thermal stability but also the thermal oxidative resistance for EVA matrix. The limiting oxygen index (LOI) of the EVA/PD-LDH@MF composite with 15 wt% loading was about 27.5%, while the composite attained V-0 rating. The observable improvement in flame retardancy of the EVA/PD-LDH@MF composite was because intercalated PEDP could promote to remain more N and C elements, and P species in PEDP participated into the connecting reaction to form the more continuous and more compact char layer on the char surface, thus hindering heat diffusion and oxygen transmission effectively.

Synthesis and Enhanced Corrosion Protection Performance of Reduced Graphene Oxide Nanosheet/ZnAl Layered Double Hydroxide Composite Films by Hydrothermal Continuous Flow Method.

Prevention of water, oxygen, and chloride ions contained in hydrotalcite interlayers from diffusing through the layered double hydroxides (LDH) is of crucial importance in corrosion protection. In this work, a hybrid composed of reduced graphene oxide (RGO) nanosheets/Zn2+/Al3+ layered double hydroxide (RGO/ZnAl-LDH) composite films on the surface of 6N01 aluminum (Al) alloy was successfully synthesized by a novel and facile hydrothermal continuous flow method, which enabled direct growth of the composite on the surface of the Al alloy substrate. The structure and morphology of the RGO/ZnAl-LDH composite films were fully characterized. Based on electrochemical measurements in a NaCl solution, the RGO/ZnAl-LDH composite film significantly enhanced the corrosion protection, as compared with the ZnAl-LDH film. The RGO/ZnAl-LDH composite film could maintain an outstanding corrosion resistance after 7 days immersion in a high concentration of NaCl solution (i.e., 5.0 wt %). The enhanced corrosion resistance was attributed to the barrier effect on diffusion of water, oxygen, and chloride ions by the RGO contained in the RGO/ZnAl-LDH composite films.

Ceria promotion over Ni-containing hydrotalcite-derived catalysts for CO2methane reforming

The catalytic activity in dry methane reforming of hydrotalcite-derived catalysts with ceria and/or nickel species introduced into hydrotalcite interlayer spaces was examined. The prepared materials were characterized (XRF, XRD, FT-IR, H2-TPR and N2 sorption) and subsequently tested in CO2 methane reforming at 550 °C. The obtained results showed that the incorporation of nickel species between hydrotalcite layers resulted in active catalyst with no sign of carbon deposition. Additionally, a beneficial effect of ceria promotion was observed. Ceria-promoted sample exhibited higher activity, stability and selectivity towards DRM, which may be explained by the formation of small Ni crystallites and prevention of the formation of inactive NiAl2O4 spinel phase.

Catalytic activity and characterization of Fe–Zn–Mg–Al hydrotalcites in biohydrogen production

Four different M2+–Mg–Al hydrotalcite (HT) materials were investigated for their effect on biohydrogen enhancement, where M2+ is Fe and/or Zn. HTs were synthesized by the coprecipitation method and characterized by infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The effect of Fe–Zn–Mg–Al HTs dose (0–833 mg/L) on hydrogen production was investigated in batch tests using sucrose-fed anaerobic mixed culture at 37 °C. The best catalytic activity was observed on Mg–Al HT at 167 mg/L with the maximum hydrogen yield of 2.30 ± 0.37 mol H2/mol sucrose, which was 44% higher than the control. The major metabolites detected in the test were acetic acid (3.6 g/L), butyric acid (4.1 g/L), and lactic acid (0.5 g/L). The basic properties of the different catalysts played an important role in stimulating or inhibiting the activity of hydrogen producing bacteria. Calcined Mg–Al HT did not promote biohydrogen production, suggesting that the catalytic enhancement was related to immobilization of bacteria in the electrostatically charged HT interlayers.

Behavior of Aluminum, Arsenic, and Vanadium during the Neutralization of Red Mud Leachate by HCl, Gypsum, or Seawater

Red mud leachate (pH 13) collected from Ajka, Hungary is neutralized to < pH 10 by HCl, gypsum, or seawater addition. During acid neutralization >99% Al is removed from solution during the formation of an amorphous boehmite-like precipitate and dawsonite. Minor amounts of As (24%) are also removed from solution via surface adsorption of As onto the Al oxyhydroxides. Gypsum addition to red mud leachate results in the precipitation of calcite, both in experiments and in field samples recovered from rivers treated with gypsum after the October 2010 red mud spill. Calcite precipitation results in 86% Al and 81% As removal from solution, and both are nonexchangeable with 0.1 mol L(-1) phosphate solution. Contrary to As associated with neoformed Al oxyhydroxides, EXAFS analysis of the calcite precipitates revealed only isolated arsenate tetrahedra with no evidence for surface adsorption or incorporation into the calcite structure, possibly as a result of very rapid As scavenging by the calcite precipitate. Seawater neutralization also resulted in carbonate precipitation, with >99% Al and 74% As removed from solution during the formation of a poorly ordered hydrotalcite phase and via surface adsorption to the neoformed precipitates, respectively. Half the bound As could be remobilized by phosphate addition, indicating that As was weakly bound, possibly in the hydrotalcite interlayer. Only 5-16% V was removed from solution during neutralization, demonstrating a lack of interaction with any of the neoformed precipitates. High V concentrations are therefore likely to be an intractable problem during the treatment of red mud leachates.

Study of the corrosion mechanism of the in situ grown Mg–Al–CO32− hydrotalcite film on AZ31 alloy

The corrosion mechanism of Mg–Al–CO32− hydrotalcite film is discussed based on its corrosion behavior and the anion-exchange or adsorption effect of Cl−. The results demonstrate that the film is very compact and acts as a barrier against Cl− attack in the early stage. Then the surface of the film is dissolved gradually due to its instability in aqueous solutions. Only after eliminating CO32−, Cl− can insert into the hydrotalcite interlayer to balance charges. Cl− cannot substitute CO32− just in NaCl solution, but can adsorb on active spots of the film to accelerate the decomposition.

Insight into the catalytic mechanism of glycerol hydrogenolysis using basal spacing of hydrotalcite as a tool

Information on the catalytic mechanism is crucial for understanding heterogeneous catalysis of glycerol hydrogenolysis. In this work, we proposed a simple and effective method to study the catalytic mechanism of glycerol hydrogenolysis with Cu/Mg–Al mixed-oxide as catalyst. This method is based on the memory effect of the hydrotalcite-derived Mg–Al mixed-oxide and the tunable property of hydrotalcite interlayer distance. The experimental results showed that the basal spacing of hydrotalcite could work as an effective tool to reflect the relationship between desorption of products and reaction conditions. With this tool, the effect of H2 pressure on glycerol hydrogenolysis was elucidated. It was found that H2 pressure affected desorption and yield of products.

Synthesis and Humidity Controlling Properties of Hydrotalcite/poly (sodium acrylate-acrylamide) Composite

Hydrotalcite/poly(sodium acrylate-acrylamide) composite was synthesized by using inverse suspension polymerization method under different hydrotalcite content, neutralization degree and ratio of monomer with orthogonal experiments. The surface morphology, structure and humidity controlling properties of composite were observed and determined. The results show that hydrotalcite/poly (sodium acrylate-acrylamide) composite is in an irregular block like structure with different size. During the polymerization process, acrylate and acrylamide monomers are successfully intercalated into the interlayer of hydrotalcite, and the distance of (003) hydrotalcite plane is increased from 0.766nm to 1.146nm. The impact of three factors on the humidity controlling behavior of composites increases by the order of ratio of monomer, hydrotalcite content and neutralization degree. The optimum preparation parameters are hydrotalcite content of 4%, neutralization degree of 90% and ratio of monomer in 9:1.

Interlayer Structure and Ion-Exchange Properties of Hydrotalcite Intercalated with CO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;, CrO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;, SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; and NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;

A double-sheets model was proposed to investigate the interlayer structure and properties of hydrotalcite (HT) containing CO32-, CrO42-, SO42- and NO3- using density functional theory, and the configuration and distribution of four anions in the interlayer of HT were obtained. The frontier orbital of the host layer interacts with that of the guest anions, and the electron transfers from HOMO of anions to LUMO of the host layer. Moreover, the order in the absolute value of binding energy is: CO32- &gt;CrO42- &gt;SO42- &gt; NO3-, that remains consistent with the ion-exchange ability of HT reported.