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In this study, we report the adsorption process of Congo Red (CR) dye by calcined Layered Double Hydroxide (ZAC) at 550°C. The urea hydrolysis method was applied to produce highly crystalline Zn2Al-LDH. Samples characterisation was carried out by X-ray diffraction (XRD), Thermogravimetric/differential thermal analysis (TG/DTA), and Fourier transform infrared spectroscopy (FTIR). The results show that the adsorption of CR on calcined ZnAl-LDH was accompanied by the reconstruction of the layered structure. The ZAC showed higher adsorption efficiency versus other adsorbent under investigation and optimum conditions of contact time, adsorbent dose, pH and temperature were found to be 50 min, 0.02 g, 7 and 318 K, respectively. Isotherm studies show that the Langmuir isotherm model was appropriate to describe the CR adsorption data compared with Freundlich and Temkin isotherm models, with a higher correlation coefficient (R2 > 0.99) and maximum adsorption capacity of 406.5 mg/g. The thermodynamic parameters revealed that the adsorption process was spontaneous, endothermic, and governed by chemisorption. To further facilitate the recovery process in CR adsorption, we test the feasibility of applying ZnAl-LDH and its calcined product at 550°C entrapped in alginate beads. Experimental results indicate that alginate-coated ZAC beads, which exhibited remarkable adsorption performance, were more stable and require less effort to pull and separate than the alginate/ZnAl-LDH composite beads.

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Mesoporous silicas are among the most suitable high-surface area solids to support small-sized metal clusters and nanoparticles. Unfortunately, the instability of silica in water constitutes a serious impediment for its widespread use and large implementation as a catalytic support for fine chemical synthesis and for biomass upgrading in the context of biorefineries. While end cupping silanols provides a way for delaying framework degradation, further investigations are needed to design more robust, water-resistant supports. Prompted by the success of polydimethylsiloxane (PDMS) in surface coating and water-repellent technologies, we herein explore the transformation of triethoxysilyl-functionalized polymethylethylsiloxane – a sol–gel analogue of PDMS – into a hydrophobic disordered mesoporous MCM-41-type siloxane framework. The concomitant addition of a soluble gold precursor during the mesophase formation followed by surfactant removal resulted in the entrapment and growth of gold nanoparticles inside. Thermally induced evolution of the PDMS-like siloxane framework was further investigated both under inert and open air atmospheres. Gold accessibility was ascertained during the transformation of nitrophenol, a harmful water pollutant, into aniline as a valuable amine-based precursor. Owing to the virtues of the PDMS-like framework for slowing down water and oxygen diffusion, the catalysts preserve their activity even after 18 months of storage under an open air atmosphere.

We report the synthesis, structural, optical and dielectric properties of single-phase spinel of Ni-substituted Zn nanoparticles prepared by co-precipitation method. The annealed samples at 1000 °C were characterized by X-ray diffraction (XRD) technique, infrared spectrophotometer (FTIR), UV–VIS spectrophotometer and dielectric measurements. X-ray diffraction analysis shows that the increase of zinc content has been manifested on crystallite size and lattice parameter. Crystallite size and lattice parameter were systematically increased from 83 to 130 nm and 8.386 to 8.443 A, for x varied from 0.5 to 0.9. The FTIR analysis show two absorption bands in the wave number range of 400–540 cm−1. The UV–VIS analysis shows that the estimated optical energy band gaps (Eg) of the samples, through Tauc plots, do not exceed 5 eV which confirms the semiconductor nature of our samples. The dielectric behavior was investigated as function of both frequency (1 kHz–1 MHz) and temperature (298–700 K), and the electrical response was investigated by impedance spectroscopy measurements.

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The aim of this research work was to study the structural and magnetic properties of iron oxide nanoparticles. The as-prepared sample was synthesized by a co-precipitation route and annealed at different temperatures. The annealed samples were investigated using different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and Mossbauer spectrometry (MS). The XRD results indicate the formation of three phases which have been identified as magnetite (Fe3O4), maghemite (γ-Fe2O3), and hematite (a-Fe2O3). The crystallite size was very similar for both magnetite and maghemite, and it was higher for hematite. The TEM observations showed that the particle shapes were affected by the annealing temperature (Tan). In addition, the SEM analysis revealed a wide distribution of the particle size. The magnetic measurements enabled the determination of a blocking temperature for both Fe3O4 and γ-Fe2O3 as 210 and 240 K, respectively. The Morin transition temperature was determined in the case of α-Fe2O3 from the magnetization and the MS measurements. The synthesized iron oxide nanoparticles can be good candidates for hyperthermia applications.

Currently, the treatment of wastewater containing dye by the effective adsorbent attracts a great deal of interest. In this work, we report the removal of Congo Red (CR) dye from water using ZnAl-L...

Nanoparticles Ni1-xZnxFe2O4 (0.4 ≤ x ≤ 0.7) samples were synthesized through co-precipitation method, and the effect of zinc concentration on the structural, magnetic, and magnetocaloric properties was investigated. X-ray diffraction patterns reveal the formation of single-phase spinel. The average crystallite size, estimated using Scherrer’s formula, was found to be ranging from 83 to 116.6 nm. The Curie temperature was found to decrease from 619 to 350 K with increasing x from 0.4 and 0.7. The Arrott plots reveal a second-order ferromagnetic transition in all samples. Magnetic entropy change (-ΔSm) allowing estimation of the magnetocaloric effect was determined based on the thermodynamic Maxwell’s relation. The (-ΔSm) was found to slightly increase with increasing x from 0.4 to 0.5 and decreasing with increasing x. The relative cooling power increases linearly with zinc content, up to x = 0.5.

A solid nanomaterial, Mg/Al-LDH (Layered Double Hydroxides) has been prepared by co-precipitation method, with ratio Mg2+/Al3+ = 3, at pH = 10.0 ± 0.2, while the physicochemical characterization has been done by XRD, TG-dTG, FT-IR and BET. In this work, we have reported the synthesis of novel pyrazoles compounds by treating substituted aromatic aldehydes with 3-Amino-1-phenyl-2-pyrazolin-5-one in the presence of Mg/Al–LDH as a catalyst with a green solvent (EtOH). The attractive features of this protocol are: mild reaction conditions, ecofriendly synthesis, good yields and easiness of the catalyst separation from the reaction mixture.