Abdelkader Bengueddach

Lead(II) removal from aqueous solutions by organic thiourea derivatives intercalated magadiite

AbstractIn this work, a layered silicate magadiite-Na (Mag) is hydrothermally synthesized and used to prepare organic thiourea-intercalated magadiite. It is organically modified by N-(2-methoxyphenyl)-N′-(2-methylphenyl)-thiourea (TMMe) and N-(2-methoxyphenyl)-N′-(2-methoxyphenyl)-thiourea (TMM) without preintercalation with a cationic surfactant. These materials are characterized by X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Due to the increment of basic centers attached to the pendant chains, the metal adsorption capacities of the final chelating materials are found to be higher than the precursor. The ability of these materials to remove Pb(II) from an aqueous solution is followed by a series of adsorption isotherms at a temperature of 25°C, pH 5 and pH 7. The kinetic parameters analyzed by the Lagergren and Ho and Mc Kay models give a good fit for a pseudo-second-order reaction for all systems. The adsorption isotherm data follow the Langmuir equation where parameters ...

Assessment of the intrinsic interactions of mesoporous silica with carbon dioxide

Three mesoporous silica, SBA-16, SBA-15 and MCM-41, with different structures and porosities were synthesized via a hydrothermal method and their interactions with carbon dioxide (CO2) were investigated through thermal programmed desorption (TPD) and differential scanning calorimetry. TPD measurements provided precise assessments of the intrinsic affinity towards CO2, without the influence of moisture. All silica materials were found to exhibit intrinsic affinity towards carbon dioxide, but the surface basicity, expressed in terms of retained CO2 amount, is markedly influenced by increases in pore size and framework structures. SBA-15 displayed the highest CRC values, explained in terms of larger pore size, lower numbers of acidic out-of plane Si–OH and higher numbers of much less acidic in-plane silanols. These findings provide valuable information for a better understanding of the role of the silica structure in the intrinsic basicity, prior to further modifications for improving the affinity towards CO2 or merely for catalysis purposes involving CO2 as reagents, intermediates or products.

Preparation and characterization of layered silicate magadiite intercalated by Cu2+ and Zn2+ for antibacterial behavior

The purpose of this work is the synthesis of two series of layered silicate materials with different ratios (10, 30, 50, 80 and 100) of Cu(NO3)2, or Zn(NO3)2 by ion-exchange method. Several analysis techniques have been used such as X-ray diffraction, energy dispersive X-ray spectroscopy, thermogravimetric analysis, scanning electron microscope and Fourier transform infrared spectroscopy. The results revealed that ion-exchange method of copper and zinc with different ratios did not affect the structure of Na-magadiite. The gap between the theoretical and experimental ion-exchange are in agreement. Antibacterial activity test against Escherichia coli, Rhizobium sp. and Staphylococcus demonstrate that when ratio was (30, 50, 80 and 100) the antibacterial activity of the layered silicate materials showed high antibacterial activity.

Sorption of Cu(II) Ions on Chitosan-Zeolite X Composites: Impact of Gelling and Drying Conditions

Chitosan-zeolite Na-X composite beads with open porosity and different zeolite contents were prepared by an encapsulation method. Preparation conditions had to be optimised in order to stabilize the zeolite network during the polysaccharide gelling process. Composites and pure reference components were characterized using X-ray diffraction (XRD); scanning electron microscopy (SEM); N2 adsorption–desorption; and thermogravimetric analysis (TG). Cu(II) sorption was investigated at pH 6. The choice of drying method used for the storage of the adsorbent severely affects the textural properties of the composite and the copper sorption effectiveness. The copper sorption capacity of chitosan hydrogel is about 190 mg·g−1. More than 70% of this capacity is retained when the polysaccharide is stored as an aerogel after supercrititcal CO2 drying, but nearly 90% of the capacity is lost after evaporative drying to a xerogel. Textural data and Cu(II) sorption data indicate that the properties of the zeolite-polysaccharide composites are not just the sum of the properties of the individual components. Whereas a chitosan coating impairs the accessibility of the microporosity of the zeolite; the presence of the zeolite improves the stability of the dispersion of chitosan upon supercritical drying and increases the affinity of the composites for Cu(II) cations. Chitosan-zeolite aerogels present Cu(II) sorption properties.

Enhanced hydrogen storage capacity of copper containing mesoporous silicas prepared using different methods

This paper focuses on the synthesis of mesoporous materials, Al-MCM-41, doped with copper using different methods. The results show that the method of synthesis affects the structural and textural properties of these solids. Their application in hydrogen storage shows that the adsorption is enhanced when using a solid containing Cu+2 ions, with an adsorption capacity around 1.8 wt% at 77 K, while the solids containing CuO particles present a medium adsorption capacity. Temperature variation plays a very important role in determining the adsorption capacity and the best results are obtained at 77 K.

Al-Rich Ordered Mesoporous Silica SBA-15 Materials: Synthesis, Surface Characterization and Acid Properties

Al–SBA-15 is an interesting mesoporous material having highly ordered nanopores and a large surface area, which is widely employed as catalysts and adsorbents, but relatively few studies on the surfaces properties of this type of materials have been carried out. The purpose of the present work was to advance knowledge on the textural properties of Al–SBA-15 by applying the accurate NLDFT method as well as to gain insight into the surface characterisation and acidic trend of this material. Mesoporous Al–SBA-15 molecular sieves, in three SiO2/Al2O3 ratios: 50, 75 and 100 were accomplished by post-synthesis alumination in aqueous solution of a purely siliceous SBA-15 material. The obtained solids were characterized using powder X-ray diffraction (XRD), X-ray fluorescence (XRF), N2 adsorption–desorption (BET/DFT), transmission electron microscopy (TEM), water adsorption and zeta potential measurements. The results indicate that Al atoms have been successfully incorporated into the framework of the hexagonal mesoporous SBA-15. The aluminum introduced amount has remarkably affected the surface properties of the SBA-15 solid, indeed microporosity decreased. Furthermore, the esterification test showed that the Al–SBA-15 material exhibit Brønsted acid properties with an interesting activity leading to yields of ~90% of biodiesel.Graphical Abstract

CuCO3–CuO nanocomposite as a novel and environmentally friendly catalyst for triazole synthesis

This paper focuses on the use of natural sources for the preparation of efficient and low cost catalysts. CaCO3 is obtained from cuttlefish bone and was modified by the cation exchange of Ca2+ by Cu2+ in CaCO3 using solutions of copper (Cu(NO3)2) at different concentrations. The modification of the solids was investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and ultraviolet-visible (UV-vis) spectroscopy. The results show that the copper exchanged materials contain a CuCO3–CuO nanoparticle composite. The obtained solids were used as catalysts for the cycloaddition reaction of different azides with activated alkenes at room temperature under liquid phase conditions. The different parameters which affect the reaction were investigated such as reaction time, temperature of the reaction, effect of the copper content, catalyst mass, effect of the solvent and nature of the azide. High yields were obtained when the catalyst contained more copper. The best catalysts were calcined at different temperatures (200, 300, 400, 500 °C) in order to determine whether the active phase was CuCO3 or CuO in the catalytic reaction. The XRD analysis of the calcined composites shows that an increase in calcination temperature leads to the formation of the CuO phase. On the other hand, the use of these calcined materials as catalysts shows that the active phase is copper carbonate. Finally, a new method for preparing triazoles with short reaction times was developed by the use of a cheap environmentally friendly catalyst.

Structure and intercalation behavior of copper II on the layered sodium silicate magadiite material

In this work, the ion-exchange reaction of the sodium silicate Na-magadiite with cupric ions was studied and the mode of interaction of the intercalated Cu2+ ions with silicate sheet was investigated. To do this, Na-magadiite was first synthesized using a hydrothermal method and characterized. It is then used to prepare Cu-exchanged magadiite materials with different copper contents by an ion-exchange reaction. The solids obtained were characterized by chemical and thermogravimetric analyses, powder X-ray diffraction, UV–Visible diffuse reflectance and Fourier transform spectroscopy, scanning electron microscopy and transmission electron microscopy. The results show that magadiite has a high affinity to copper ions and that the experimental exchange rate can be easily predicted. They show also that the intercalated Cu2+ ions are non-hydrated and are in direct interactions with the terminal interlayer ≡Si–O− groups, to which they are also probably strongly linked. Furthermore, the interlayer copper oxide species phase formed are in form of small particles homogeneously dispersed. Finally, the introduction of Cu2+ ions into the interlayer space does not substantially affect the structure of the Cu-exchanged materials but rather tends to stabilize it by increasing the decomposition temperature of the silanol groups .

CuNPs-magadiite/chitosan nanocomposite beads as advanced antibacterial agent: Synthetic path and characterization

In this work, an inorganic-organic nanocomposite was prepared by combining copper exchanged-magadiite (Cu-magadiite) with chitosan. The synthesis was carried out by direct dispersion of the Cu-magadiite in the chitosan matrix. The mixture obtained is shaped into beads with an average diameter of about 1-1.2 mm. These beads were then contacted with a solution of NaBH4 in order to reduce loaded copper ions into copper nanoparticles species. The resulting nanocomposite (Cu-NPs-magadiite/chitosan) was characterized by XRD, FTIR, SEM, TG, UV-visible DR and EDX analysis. The results show that the magadiite was completely exfoliated confirming the formation of the organic-inorganic composite. Indeed, the encapsulation of magadiite was confirmed by the SEM images, which is presented as micron free aggregates included in the cavities of a continuous polysaccharide matrix. Otherwise, they confirm also the formation of CuNPs which are probably immobilized inside the magadiite-chitosan solid matrix. The antibacterial activity against E. coli and S. aureus was highlighted by the disc inhibition method and the minimum inhibitory concentration (MIC) was determined. The CuNPs-magadiite/chitosan nanocomposite showed a very efficient bactericidal effect against both pathogen bacteria. Additionally, the MIC values obtained for nanocomposite are of 0.25 μg/L against S. aureus and of 0.50 μg/L against E. coli.

Preparation of Al-magadiite material, copper ions exchange and effect of counter-ions: antibacterial and antifungal applications

In this work, the Al-magadiite is synthesized by the hydrothermal method. It is then used to prepare three copper exchanged materials using copper nitrate, copper chloride, and copper sulfate salts. The materials obtained were characterized and applied as antibacterial and antifungal agents against pathogen strains. The characterization methods showed the presence of four coordinated aluminum atoms in the magadiite framework. The presence of aluminum leads to the total exchange of interlayer sodium cations. Otherwise, the copper exchange rate is influenced by the nature of the counter-ion used. Indeed, the exchanged rate increased in the sense of copper nitrate > copper chloride > copper sulfate. The chemical analysis shows that the ion exchange of Al-magadiite with copper salts is accompanied with dehydration of Cu-exchanged materials. This result was confirmed by XRD diffraction, chemical analysis, and FTIR spectroscopy. This dehydration depends on the nature of the counter ion increase also in the sense of copper nitrate > copper chloride > copper sulfate. Tested as antibacterial and antifungal materials against pathogens strains, all the copper exchanged materials exhibited a good antibacterial activity against Gram-positive bacteria which increased with increasing the copper content of a sample. The best activity was observed in the exchanged sample prepared from copper nitrate. However, a low or no activity is observed against Gram-negative bacteria.