Layered Double Hydroxide Nanocomposites Research Articles

Dihydroartemisinin loaded layered double hydroxide nanocomposites for tumor specific photothermal-chemodynamic therapy.

With the inspiration to develop new cancer nanotherapeutics by repurposing old drugs, in the current study, a novel two dimensional nanomedicine namely Mn doped, dihydroartemisinin (DHA) loaded layered double hydroxide (MnMgFe-LDH/DHA) with peroxide self-supplying properties for enhanced photothermal-chemodynamic therapy was proposed. Such nanostructures could be synthesized by a simple coprecipitation method, and the as-prepared MnMgFe-LDH/DHA exhibits excellent photothermal properties with a photothermal conversion efficiency up to 10.7%. Besides, the in situ reaction between the released DHA and Fe2+/Mn2+ produced by the degradation of LDH can lead to a burst of intracellular reactive oxygen species (ROS) by Fenton-like reactions. Furthermore, the in vivo experiments demonstrate that MnMgFe-LDH/DHA exhibits a remarkable chemodynamic/photothermal therapy (CDT/PTT) synergistic effect on tumor treatment with negligible damage to normal tissues. Finally, this research provides a smart strategy to construct a DHA repurposing nanomedicine for tumor specific treatment.

Preparation of polymer functionalized layered double hydroxide through mussel-inspired chemistry and Kabachnik–Fields reaction for highly efficient adsorption

A novel method for the fabrication of phosphorylated layered double hydroxide (LDH) based adsorbents was proposed, in which polydopamine and α-amino phosphonate chains were anchored onto the pristine LDH nanosheets by a combinatorial procedure of mussel-inspired chemistry and Kabachnik-Fields (KF) reaction. The modified LDH adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Various adsorption conditions, including contact time, pH, Cu2+ concentrations, and solution temperature was further investigated. Kinetics results revealed that the pseudo-second-order model can provide a better depiction of adsorption data. The modified LDH exhibited a better adsorption capacity towards Cu2+ owing to the introduction of oxygen-containing groups. Adsorption isotherms showed that the adsorption data can be well represented by the Langmuir isotherm model. The maximum adsorption capacity was calculated to be 105.44 mg g−1. Thermodynamic results indicated that the adsorption features of Cu2+ on phosphorylated LDH nanocomposites were spontaneous and endothermic. The electrostatic attraction was proposed as the dominant adsorption mechanism. In summary, this work not only brings about a discovery of surface modification of LDH-based materials via an effective and versatile combinatorial method, but also provides new avenues to architecturally construct various multifunctional hybrid materials for many high-value applications, such as advanced oxidation technology, oxygen reduction reaction, photocatalyst, supercapacitor.

New electroactive and photosensitive polyamide/ternary LDH nanocomposite containing triphenylamine moieties in its backbone: synthesis and characterization

The new ternary (Mg–Zn–Al–) layered double hydroxide (LDH) with an organic modifier-containing azo group (LDH–SHDBS) as a guest anion was prepared by a co-precipitation through one-step synthetic method. The novel electroactive polyamide (EPA) was successfully prepared by direct polycondensation reaction of azelaic acid with a new synthetic diamine 4. The structure of diamine 4 was confirmed by FTIR and 1H NMR spectra. Also, polyamide/ternary LDH nanocomposites were prepared by resulting EPA and modified ternary LDH under ambient condition. The resulting data using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) showed ternary LDH were successfully distributed into the EPA matrix. Thermal behavior of the EPA and its nanocomposites were studied by thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG). The presence of LDH layers into EPA matrix improved thermal stability (T5, T10, char yield) in both air and nitrogen atmospheres. Also, photoisomerization and electrochemical behaviors of EPA and resulting nanocomposites were measured using UV–Vis spectroscopy and cyclic voltammetry (CV), respectively. The UV–Vis spectrum of the obtained nanocomposites showed two peaks at λmax = 422 and 480 nm related to π–π∗ and n–π∗ transitions of trans azobenzene. Moreover, trans to cis isomerization of azomoieties was studied by irradiation of the nanocomposites under 254 nm photons. The CV pattern of EPA exhibited a reversible anodic peak around 0.84 V, corresponding to the nitrogen atom of triphenylamine unit into polymer backbone that improved by incorporation of LDH–SHDBS into EPA matrix.

Investigating the Use of Layered Double Hydroxide Nanoparticles as Carriers of Metal Oxides for Theranostics of ROS-Related Diseases.

Overproduction of reactive oxygen species (ROS) is commonly known as a key factor in the progression of many chronic inflammation diseases such as atherosclerosis and rheumatoid arthritis. In this study, a metal oxide nanodot-coated layered double hydroxide (LDH) nanocomposite is constructed for theranostics of ROS-related diseases. This is the first time that both cerium oxide and iron oxide nanoparticles (NPs) were attached on the surface of LDH NPs through electrostatic interaction via a nanoengineering approach. LDHs served as nanocarriers, cerium oxide NPs served as therapeutic agents due to the antioxidant properties, and iron oxide NPs served as magnetic resonance imaging (MRI) contrast agents. In vitro studies have demonstrated that the constructed nanocomposites have good biocompatibility, good antioxidant capacity to reduce ROS level in the cells, as well as satisfying cell imaging effect in MRI. Functionalization of LDH surface with cerium oxide NPs and iron oxide NPs allows the simultaneous therapy and diagnosis of ROS-related diseases and may also allow biodistribution tracking of the therapeutic cerium oxide NPs.

Effect of polarization switching on piezoelectric and dielectric performance of electrospun nanofabrics of poly(vinylidene fluoride)/Ca–Al LDH nanocomposite

ABSTRACTAt present, highly flexible, durable, and lightweight piezoelectric nanogenerators with high‐power density and energy conversion efficiency are of great interest. The present study reports a new synthetic route for Ca–Al layered double hydroxide (LDH) nanosheets and incorporation of these two‐dimensional nanosheets as filler material into poly(vinylidene fluoride) (PVDF) to produce composite nanofabrics by electrospinning. The polymorphism, crystallinity, and the interaction between PVDF and LDH were studied by Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry techniques. The synergetic effect of PVDF–LDH interaction and in situ stretching due to electrospinning facilitates the nucleation of electroactive β phase up to 82.79%, which makes it a suitable material for piezoelectric‐based nanogenerators. The piezoelectric performance of PVDF/Ca–Al LDH composite nanofabrics was demonstrated by hand slapping and frequency‐dependent mechanical vibration mode, which delivered a maximum open circuit output voltage of 4.1 and 5.72 V, respectively. Moreover, the composite nanofabrics exhibited a high dielectric constant and low dielectric loss due to superior interfacial polarization at low‐frequency region with LDH loading, promising its potential applications in electronic devices. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48697.

A magnetic core-shell dodecyl sulfate intercalated layered double hydroxide nanocomposite for the adsorption of cationic and anionic organic dyes

A magnetic dodecyl sulfate (DS−) anions intercalated layered double hydroxide (LDH) nanocomposite, Fe3O4@(DS-LDH), was synthesized by coprecipitation-ion exchange method. The Fe3O4@(DS-LDH) nanocomposite was characterized and the results showed that the Fe3O4@(DS-LDH) particles possessed core (Fe3O4)-shell (DS-LDH) structures and magnetic properties, and DS− anions were successfully introduced into LDH interlayers. Adsorption of cationic methylene blue (MB) or anionic methyl orange (MO) by Fe3O4@(DS-LDH) were comprehensively clarified with magnetic separation in (MB or MO) sole and (MB + Cu(II) or MO + Cu(II)) binary solutions by adsorption kinetics, thermodynamic and isotherm models. The adsorption of both MB and MO on Fe3O4@(DS-LDH) were governed by the pseudo-second-order kinetic model. The adsorption isotherm data for MB (in sole and binary solutions) and MO in binary solution agreed well with the Freundlich model, and that for MO in sole solution was accorded with the linear model. MB uptake decreased with the addition of Cu(II) ions, whereas the existence of Cu(II) ions enhanced MO removal. According to the adsorption mechanism investigation by XRD and XPS analysis, the main driving force for MB/MO adsorption, the hydrophobic interaction between MB/MO molecules and the three-dimensional hydrophobic region formed by DS−anions in LDH interlayers of Fe3O4@(DS-LDH), was proposed; Cu(II) ions could act as a bridge between Fe3O4@(DS-LDH) and MO, which slightly enhanced MO adsorption; whereas, the adsorption capacity for MB decreased in the presence of Cu(II) ions due to competitive adsorption.

Alginate-chitosan coated layered double hydroxide nanocomposites for enhanced oral vaccine delivery

Layered double hydroxide nanoparticles (LDHs) have shown the excellent capability and good adjuvant function as a nanocarrier for protein antigen delivery to enhance the immune response. Furthermore, LDHs have good biocompatibility and low cytotoxicity. However, their oral vaccine delivery efficiency is limited due to acidic/enzyme degradation in the stomach and low bioavailability in the small intestine. To overcome these challenges, alginate-chitosan coated LDHs nanocomposites (ALG-CHT-LDH) have been developed and used as a carrier for oral protein vaccine delivery. The physicochemical properties of ALG-CHT-LDH have been determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and ultraviolet visible (UV–Vis) spectroscopy. Protein release properties of LDHs with/without polymer coating have been investigated at various pHs. The protein release profile of ALG-CHT-LDH nanocomposites indicated that ALG-CHT coating could partially protect protein release at the acidic condition (pH 1.2). The cellular uptake efficiency of protein delivered by ALG-CHT-LDH for the intestine cells and macrophages were studied. After alginate layer falls from ALG-CHT-LDH nanocomposite, flow cytometry analysis (FACS) data suggest that chitosan-coated LDHs significantly enhance the internalization of proteins at the Caco2 and macrophage cells.

Epoxy/layered double hydroxide (LDH) nanocomposites: Synthesis, characterization, and Excellent cure feature of nitrate anion intercalated Zn-Al LDH

Layered double hydroxides (LDHs) belong to two-dimensional (2D) nanoparticle family. Best known as anionic clays, LDHs were the promising choice for a wide range of applications. Despite the widespread research on synthesis and application of LDH as an additive in thermoset resins, a few was known about its curing ability. In this work, Zn-Al LDH intercalated with nitrate anion (Zn-Al-NO3) was synthesized, characterized and incorporated into epoxy resin at low content of 0.1 wt.%. Fourier-transform infrared spectrophotometry (FTIR), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA/DTG) techniques were employed to characterize LDH. Nonisothermal differential scanning calorimetry (DSC) at different heating rates allowed for evaluating curing state of epoxy/Zn-Al-NO3 LDH nanocomposites containing 0.1 wt.% of LDH in terms of Cure Index universal criterion. Zn-Al-NO3 LDH assisted epoxy in curring with an amine precursor resulting in much more heat release in a shorter curing temperature interval with respect to the blank epoxy system whatever heating rate. Such promising feature was signaled by Excellent cure state demonstrated by Cure Index, which was attributed to Lewis acid effect of Zn that catalyzed epoxy curing reaction. Moreover, it was discussed that an enlarged LDH interlayer space brought about by incorporation of nitrate anion between layers facilitated the curing reaction.

Layered double hydroxide nanostructures and nanocomposites for biomedical applications.

Layered double hydroxide (LDH) nanostructures and related nanocomposites have attracted significant interest in biomedical applications including cancer therapy, bioimaging and antibacterial treatment. These materials hold great advantages including low cost and facile preparation, convenient drug loading, high drug incorporation capacity, good biocompatibility, efficient intracellular uptake and endosome/lysosome escape, and natural biodegradability in an acidic environment. In this review, we summarize the development of three types of LDH nanostructures including pristine LDH, surface modified LDH, and LDH nanocomposites for a range of biomedical applications. The advantages and disadvantages of LDH nanostructures and insights into the future development are also discussed.

Properties of Polystyrene (PS)/Co-Al LDH Nanocomposites Prepared by Melt Intercalation

This work presents the preparation of organically modified Co-Al layered double hydroxide (LDH) and its effective utilization in synthesis of polystyrene (PS) nanocomposites. Various PS nanocomposites were prepared by inclusion of different quantity of Co-Al LDH (1, 3, 5 and 7 wt.% with respect to PS) in a PS matrix via melt intercalation using a twin screw extruder. The dispersion and morphology of the obtained PS nanocomposites were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Mechanical and thermal properties of the PS nanocomposites as a function of LDH content were examined by tensile tests, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD results revealed the formation of an exfoliated structure; however, TEM images clearly indicated the intercalated morphology of PS nanocomposites at higher content of LDH. TGA data demonstrated that the thermal stability of PS nanocomposite with 7 wt.% Co-Al LDH content was increased by 26.1 °C over pristine PS, when 15% mass loss was taken as a reference point. The glass transition temperature (Tg) of PS nanocomposites was better than that of pristine PS. The activation energy (Ea) and reaction mechanism on thermal degradation of pristine PS and respective nanocomposites were evaluated by employing Coats-Redfern and Criado model, respectively. The research findings demonstrated that mechanical and thermal properties were found to be strongly dependent on the Co-Al LDH content. The maximum improvement of tensile strength observed with PS nanocomposite containing 1 wt.% Co-Al LDH over pristine PS was 32%. Overall, the prepared PS nanocomposites exhibited superior properties such as improved degradation temperature and mechanical properties, compared with those of PS without LDH.

Synthesis and Characterization of Polystyrene (PS)/Modified Ni‐Al LDH Nanocomposite: Role of Composition, Modifier and Synthesis Route of Layered Double Hydroxides (LDH)

Layered double hydroxides (LDH) are two‐dimensional nanostructured materials, which impart flame retardancy property and improvement in various properties on incorporation into the polymer matrix. In this study, Ni‐Al LDH with a molar ratio of 2:1 and 3:1 (2NiAl and 3NiAl) was prepared by co‐precipitation method and Ni‐Al LDH with a molar ratio of 2:1 (NiAl urea) was also synthesized by the urea hydrolysis method. As the d‐spacing of these as‐synthesized LDHs is very small (≈0.8 nm) as well as hydrophilic in nature, hence, the unmodified LDHs are unsuitable for polymer nanocomposite preparation. In order to enhance the d‐spacing of LDHs, a simple regeneration method was employed to organically modify LDHs using two anionic surfactants such as sodium dodecyl benzene sulfate (SDBS) and sodium dodecyl sulfate (SDS). The hydrophobic tail of these anionic surfactants replaced the nitrate ions present in the unmodified LDHs leading to higher d‐spacing value, which was evident from XRD analysis. The above prepared LDHs (3 wt%) were incorporated into PS matrix by the solvent blending method to make PS nanocomposites. The 003 peak of modified LDHs did not appear in the XRD pattern of PS nanocomposites due to the disorientation of LDH layers in the PS matrix that was confirmed by TEM analysis. The TGA results clearly demonstrated that the thermal stability of the PS nanocomposite samples was increased by 26, 22 and 22 °C (PS/2NiAl SDS, PS/3NiAl SDS, and PS/NiAl urea SDS) for SDS modified LDH fillers, while in the case of SDBS modified LDH fillers, the improvement was around 32 °C in comparison with PS, when 15% weight loss was taken as a reference. The degradation mechanism, thermal degradation kinetics, and integral procedural decomposition temperature (IPDT) for all the nanocomposite systems were also evaluated using Criado method, Coats‐Redfern method, and Doyle's method, respectively. The effect of dispersion of the modified LDH fillers into PS matrix was examined using melt rheological analysis.

Preparation, Performance, and Kinetics of Poly(Lactic‐Acid)/Amidated Benzoic Acid Intercalated Layered Double Hydroxides Nanocomposites by Reactive Extrusion Process

Poly(lactic acid)/amidated benzoic acid intercalated layered double hydroxides (PLA/AB‐LDH) nanocomposites were synthesized by reactive extrusion process using zinc acetate, L‐lactide, and AB‐LDH, in which the zinc acetate was severed as catalyst, L‐lactide as raw material and AB‐LDH as nucleating agent. The prepared PLA/AB‐LDH nanocomposites were characterized by Fourier transform infrared (FTIR) and X‐ray diffraction (XRD) and so on. The test results showed that PLA/AB‐LDH nanocomposites had α‐crystal structure. The analysis results of mechanical test, scanning electron microscopy (SEM), differential scanning calorimeter (DSC), and polarized optical microscopy (POM) demonstrated that the toughness, crystallinity, crystallization rate, and nucleation density of PLA/AB‐LDH nanocomposites had been significantly enhanced. In addition, the thermal degradation kinetics further indicated that AB‐LDH could improve the thermal stability of PLA significantly. POLYM. COMPOS., 40:2668–2680, 2019. © 2018 Society of Plastics Engineers

Layered double hydroxide and microwave assisted functionalized carbon based nanocomposites as controlled release vehicle for antibiotics

In this work, the preparation of new composite from layered double hydroxide (LDH) and surface modified carbon (AC) was elaborated. The basic carbon was obtained by carbonizing Ipomoea carnea stems at 500 °C. The LDH compound was furthermore intercalated with antibiotic molecule norfloxacin (NOR). The chemically activated functionalized carbon particles had surface negative charge which helped in intense interaction with LDH basal positive charges. The prepared nanocomposites were characterized by powder XRD, FT−IR, FE−SEM with EDS, TGA, Zeta potential and BET surface specific area. Powder XRD and SEM studies proved that LDH was deposited over the AC surface homogeneously. The increase of the basal spacing from 0.78 nm to 1.33 nm indicated that not all LDH sheets were intercalated by NOR. Additionally, the water dispersional stability test has shown remarkable advantage compared to simple LDH. The thermal analysis results further showed a good improvement of NOR stability after intercalation into AC−LDH nanocomposite. The release behavior of NOR from the nanocomposite and its antibacterial activity were also investigated. The gradual release of NOR from AC−LDH−NOR nanocomposite suggests its prospective application as an effective delivery system for prolonged drug release.

Preparation, characterization, structure‐property relationships, and thermal degradation kinetics of poly (lactic acid)/amidated potassium hydrogen phthalate intercalated layered double hydroxides nanocomposites

A novel nucleating agent, amidated potassium hydrogen phthalate intercalated layered double hydroxides (AP‐LDHs) were prepared using an amidation reaction. Through the structural characterization, it was found that AP‐LDHs had been successfully prepared. Meanwhile, the antibacterial activity of AP‐LDHs was studied. In order to improve the performance of poly (lactic acid) (PLA), PLA/AP‐LDHs nanocomposites were prepared by melt blending. Morphological analysis showed that PLA nanocomposites had an exfoliated structure. Mechanical properties test showed that the mechanical properties of PLA nanocomposites were enhanced. And the fracture scanning electron microscope analysis indicated that the PLA/AP‐LDHs nanocomposites exhibited ductile fracture characteristics. Moreover, differential scanning calorimetry and polarized optical microscopy analysis results demonstrated that the crystallization rate, nucleation density, and crystallinity of PLA/AP‐LDHs were improved. Thermogravimetric analysis and thermal degradation kinetics showed that the thermal stability of the PLA nanocomposites was significantly improved.

Catalytic partial oxidation of CH4 to syn gas (H2/CO) in presence of N2O over periclase type SiO2@Ni(Mg,Al)O catalyst synthesized by non aqueous route

Periclase type Ni/Mg/Al mixed-metal oxide prepared from sol-gel derived SiO2@Ni-Mg-Al Layered Double Hydroxides (LDH) nanocomposite at SiO2:LDH ratios 0:1 and 1:1 was used as a catalyst for catalytic partial oxidation (CPO) of CH4 in presence of N2O as well as oxygen. The catalysts were characterized by XRD, BET surface area, H2-TPR and XPS analysis. The presence of SiO2 dispersant influenced the catalytic property. The nascent oxygen formed by the decomposition of N2O does not re-oxidize Ni0 like molecular oxygen which act as the active species and leads to partial oxidation of CH4. SiO2@Ni-Mg-Al (1:1) catalyst showed about 99.99% H2 and 99.8% CO yield between the temperature range of 200-500 °C.

Stability of Calcium–Alumino Layered-Double-Hydroxide Nanocomposites in Aqueous Electrolytes

Calcium–alumino layered-double-hydroxide (LDH) nanocomposites of the alumino–ferrite monosubstituent subgroup hosting alkyl sulfates and poly(ethylene glycol) were synthesized by coprecipitation over the temperature range 5–75 °C. The stability of these nanocomposites was examined following exposure to aqueous solutions conditioned to a range of concentrations of intercalant anions including sulfate, carbonate, chloride, and phosphate. Careful analysis of these “organic–inorganic” nanocomposites reveals that their gallery (interlayer) spacing can vary, and the gallery height is controlled by the chain length (size) and orientation of the surfactant substituents, where, expectedly, anionic surfactants intercalate more robustly than nonionic surfactants. Upon anion exposure, in general, the nanocomposites (i) are unstable at SO42–(aq) ≥ 10 mM, wherein they convert to the AFt (ettringite) phase, (ii) form solid solutions containing carbonate for CO32–(aq) ≤ 1.5 mM and which coexist with calcite at higher carbonate concentrations, (iii) form solid solutions containing phosphate at PO43–(aq) ≤ 1.45 mM and convert to hydroxyapatite at higher phosphate abundance, and (iv) form solid solutions for Cl–(aq) ≤ 100 mM, but at higher concentrations, Cl– displaces the surfactants, forming Friedel’s salt. These insights into the stability and phase relationships for calcium–alumino LDH nanocomposites improve our understanding of these materials for applications including contaminant sorption, as carriers for the functional release of chemical additives in construction materials, and in biotherapeutic applications.

Phosphorus recovery through adsorption by layered double hydroxide nano-composites and transfer into a struvite-like fertilizer

Phosphorus (P) recovery from waste streams is attracting more attention due to the twin problems of aquatic eutrophication and global phosphorus scarcity. Layered double hydroxide mineral materials are promising phosphate adsorbents due to their excellent anion-exchange abilities and large surface area. In this study, the adsorption isotherms estimated the saturation capacity of calcined layered double hydroxide (LDH) nano-composites for phosphate as 100.7 mg-P/g-adsorbent. Ion exchange is proposed as the major mechanism in the sorption process. The commonly utilized desorption method via sodium hydroxide was found to cause recrystallization of LDH particles in increased crystal size based on the dissolution-reprecipitation (D-R) mechanism. Ammonia solution was used to desorb P from LDH adsorbent. However, struvite crystallization occurred during the desorption process because struvite has a higher precipitation tendency than LDH with sufficient NH4+ ions. The comparison of P leaching behavior among P-adsorbed LDH, ammonia-treated LDH, and pure struvite samples demonstrates that ammonia desorption probably weakened the interaction between phosphate species and LDH cationic layers, thus enhancing the bioavailability of P in LDH adsorbents. The ammonia-treated LDH has a high potential to serve like struvite as a P slow-releasing fertilizer.

Evaluation of highly efficient on-line yarn-in-tube solid phase extraction method for ultra-trace determination of chlorophenols in honey samples

In this study a novel “yarn-in-tube” configuration was introduced by packing cotton yarn inside stainless steel cartridge named packed yarn-in-tube solid phase extraction (yarn-IT-SPE) followed by high performance liquid chromatography. For the first time, cotton yarns were coated with a new polypyrrole@copper-chromium-iron ternary layered double hydroxide nanocomposite (Yarn@PPy@Cu-Cr-Fe LDH). The yarn@PPy@Cu-Cr-Fe LDH sorbent exhibited flexible substrate, high porosity, a three-dimensional, high sorbent loading, long lifetime, good mechanical stability, high anion-exchange capacity and large specific surface area as a result it is a good choice for the separation and preconcentration of acidic cholorophenols in honey samples. Several important factors affecting extraction efficiency such as extraction and desorption times, pH of solution and flow rates of the sample solution and eluent were investigated and optimized. Under the optimal conditions, the limits of detection were in the range of 0.05–0.07 μg L−1. This method showed good linearity for chlorophenols in the range of 0.10–500 μg L−1, with coefficients of determination better than 0.9989. The inter- and intra-assay precisions (RSD%, n = 5) were in the range of 3.2–4.9% and 2.1–3.6% at three concentration levels of 2, 10 and 20 μg L−1, respectively. The validated method was successfully applied for analysis of 4-chloro-, 2,4-dichloro-, and 2,4,6-trichloro phenols in honey samples.

Visible-Light-Induced Graphitic-C3N4@Nickel-Aluminum Layered Double Hydroxide Nanocomposites with Enhanced Photocatalytic Activity for Removal of Dyes in Water.

One of the major challenges in photodegradation of organic dyes is designing a visible light active and highly efficient photocatalyst that can degrade both cationic and anionic dyes. To design such an ideal catalyst, this work synthesized graphitic-C3N4@NiAl layered double hydroxide nanocomposites (g-C3N4@NiAl-LDH NCPs) with various g-C3N4 contents through a convenient and high-yield method. The photocatalytic process was optimized by evaluating the impacts of type of dye (cationic and anionic), photocatalyst dosage, pH, and contact time. According to the results, the photocatalytic performance of g-C3N4@NiAl-LDH NCPs in degradation of cationic and anionic dyes is more noticeable than the photocatalytic activities of its discrete components. The observed improvement in the photocatalytic performance of the g-C3N4@NiAl-LDH NCPs can be attributed to the intimacy of their contact interfaces and a synergistic effect between pristine g-C3N4 and NiAl-LDH, which results in effective mass transfer and separation of photogenerated charge carriers. The impact of some charge scavengers on the process was evaluated to define the role of each active species and propose a possible photodegradation mechanism. The g-C3N4@Ni-Al LDH NCPs could be reused for four cycles without any significant loss in efficiency.

Preparation and Characterization of Magnetic Chitosan/Cu–Mg–Al Layered Double Hydroxide Nanocomposite for the One-Pot Three-Component (A3) Coupling of Aldehydes, Amines and Alkynes

Magnetic chitosan/Cu–Mg–Al layered double hydroxide (mCSLDH) nanocomposite was prepared and copper(II) ions were immobilized in the prepared composite. The nanocomposite [(Cu-mCSLDH)] was characterized by FT-IR, XRD, VSM, AAS, EDX, SEM and TEM. The utility of nanocomposite was investigated in the one-pot three-component (A3) coupling of aldehydes, amines and alkynes to produce propargylamines. The Cu-mCSLDH nanocomposite is found to be highly efficient and recyclable heterogeneous catalyst.