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Akir S.,Center National Of Recherches En Science Des Materiaux Cnrsm | Ghrib T.,University of Dammam | Daoudi K.,University of Sharjah | Gaidi M.,University of Sharjah
Journal of Alloys and Compounds | Year: 2016

In this study, undoped and Fe doped nanostructured Zinc oxide thin films were synthesized by simple and low cost co-precipitation and spin-coating technique. Surface morphology and crystalline structure of the deposited films were investigated by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) techniques. XRD analysis demonstrated that the films were polycrystalline with the hexagonal phase. From SEM investigations, the surface morphology of the deposited films was found to depend on Fe concentration. The obtained optical measurements indicated that Fe doping decreases the optical transmission and shift the optical gap to 3.08 eV for 0.5 at.% Fe content. An optimum Fe concentration of 0.5 at.% was found to lead to the highest photoconduction sensitivity of the ZnO films. The photocurrent enhancement response was explained by a better charge separation and collection efficiency under visible light illumination. © 2016 Elsevier B.V. All rights reserved.


Jaouadi M.,University of Tunis | Jaouadi M.,Center National Of Recherches En Science Des Materiaux Cnrsm | Hbaieb S.,University of Tunis | Guedidi H.,University of Savoy | And 3 more authors.
Journal of Saudi Chemical Society | Year: 2016

An activated carbon was prepared by phosphoric activation of olive pomace and further oxidation by nitric acid. Another carbon was obtained from β-cyclodextrin dehydration in concentrated sulfuric acid. A composite of the oxidized activated carbon and the carbon from β-cyclodextrin was prepared. The four materials were characterized by N2 adsorption-desorption measurements, X-ray diffraction, infrared and Raman spectroscopies, elemental analysis, "Boehm" titration and measurements of pH of the point zero charge. The obtained adsorbents were tested for boron adsorption in aqueous solution. Despite their lowest specific surface areas, the composite carbon and the amorphous carbon from cyclodextrin dehydration showed the highest boron adsorption uptake (1.41 and 1.68mg·g-1) compared to the raw (1.05mg·g-1) and oxidized (0.95mg·g-1) activated carbons. The surface chemistry particularly rich in phenolic groups was responsible for the high boron adsorption uptake of the carbon composite and the amorphous carbon, both prepared through cyclodextrin dehydration. © 2016 King Saud University.


Turki A.,Laboratoire Of Chimie Des Materiaux Et Catalyse | Turki A.,Institute National Of Recherche Et Danalyse Physico Chimique | Kochkar H.,Laboratoire Of Chimie Des Materiaux Et Catalyse | Kochkar H.,Center National Of Recherches En Science Des Materiaux Cnrsm | And 3 more authors.
Applied Catalysis B: Environmental | Year: 2013

The influence of the sodium content on thermal stability and photocatalytic activity of calcined titanate nanotubes (TNT) was herein evaluated by preparing different samples through hydrothermal treatment of TiO2 powder (P25) in a concentrated NaOH solution (11.25M) at 130°C during 20h followed by acid washing steps. Titanate nanotubes samples with sodium (Na-TNT) and sodium-free (H-TNT) were then obtained using different concentrations of HCl aqueous solutions namely 0.1M and 1M respectively. As synthesized nanomaterials with different Na percentages were then calcined at temperatures varying between 400°C and 700°C. Samples were characterized by means of nitrogen adsorption-desorption isotherms at 77K, thermal analysis (DTA, TGA), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and diffuse reflectance spectroscopy (DRS). The photocatalytic activities of Na-TNT and H-TNT derived nanomaterials were then evaluated through the photocatalytic degradation of formic acid (FA).Results show that the presence of sodium retards the dehydration process during the transformation of titanate into TiO2 shifting the formation of anatase phase to higher temperatures. However, sodium is not necessary to preserve the nanotubular morphology. The presence of sodium after calcination strongly impacts negatively the photocatalytic properties. If sodium is completely removed from the initial titanate orthorhombic phase, calcination leads to TiO2 anatase materials with enhanced photocatalytic properties compared to P25 in the degradation of formic acid, particularly if nanotubular morphology is preserved. The highest activity was therefore achieved for the H-TNT sample calcined at 400°C. The photodegradation activity of formic acid depends on the specific surface areas and TiO2 crystallinity. In pure anatase nanoparticles the activity strongly decreases with coherent crystallographic domains ≥10nm. © 2013 Elsevier B.V.


Mellah B.,Center National Of Recherches En Science Des Materiaux Cnrsm | Lee Y.H.,University of Ulsan | Kim D.I.,Kyungwoon University | Cho J.H.,Kosin University | Kim Y.,Kosin University
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2015

A first-generation calix-dendrimer 1 suitable as a multidentate ligand for metal-ion binding was prepared from 1,3,5-tris(aminomethyl)-2,4,6-trimethylbenzene as the dendrimer core and p-tert-butylcalix [4] arene monomethyl ester as a repetitive branch, and characterized by spectroscopic techniques. © 2015 Springer Science+Business Media.


Triki M.,Center National Of Recherches En Science Des Materiaux Cnrsm | Ksibi Z.,Tunis el Manar University | Ghorbel A.,Tunis el Manar University | Medina F.,Rovira i Virgili University
Journal of Sol-Gel Science and Technology | Year: 2011

Catalytic wet air oxidation of an aqueous solution of p-hydroxybenzoic acid was conducted over ruthenium catalysts (1 wt%) supported on CeO 2-Al 2O 3 aerogels mixed oxides at 140 °C and 50 bars of air. We study the effect of the amount of CeO 2 in the catalyst. We found that the optimal cerium content in the Al 2O 3 support was 20 wt%. The activity of the Ru/Al 2O 3 and Ru/CeO 2 was also tested for comparison. It was found that the addition of CeO 2 on the alumina support improves the activity of Ru catalysts. The activity of the samples decreases in the following order: Ru/Ce-Al (20) > Ru/Ce-Al (10) > Ru/Ce-Al (5) ≈ Ru/Al 2O 3 > Ru/CeO 2. Samples characterization was performed by means of N 2 adsorption-desorption, XRD, UV-Vis, TPR, SEM and TEM. © 2011 Springer Science+Business Media, LLC.


Mehri A.,Laboratoire Of Chimie Des Materiaux Et Catalyse | Kochkar H.,Center National Of Recherches En Science Des Materiaux Cnrsm | Daniele S.,CNRS Research on Catalysis and Environment in Lyon | Mendez V.,CNRS Research on Catalysis and Environment in Lyon | And 2 more authors.
Journal of Colloid and Interface Science | Year: 2012

One-pot deposition of Pd onto TiO 2 has been achieved through directly contacting palladium(II) salt with nanosized functionalized TiO 2 support initially obtained by sol-gel process using titanium isopropoxide and citric acid. Citrate groups act as functional moieties able to directly reduce the Pd salt avoiding any further reducing treatment. Various palladium salts (Na 2PdCl 4 and Pd(NH 3) 4Cl 2·H 2O) and titanium to citrate (Ti/CA) ratios (20, 50, and 100) were used in order to study the effect of the nature of the precursor and of the citrate content on the final Pd particle size and catalytic properties of the as-obtained Pd/TiO 2 systems. Characterization was performed using N 2 adsorption-desorption isotherms, ICP-AES, FTIR, XRD, XPS, and TEM. The as-obtained hybrid Pd/TiO 2 catalysts were tested in the selective hydrogenation (HYD) of an α,β-unsaturated aldehyde, i.e. cinnamaldehyde. Citrate-free Pd/TiO 2-based catalysts present lower selectivity into saturated alcohol. However, citrate-functionalized Pd/TiO 2 catalyst seems to control the selectivity, the particle size and dispersion of Pd NPs leading to high intrinsic activity. © 2011 Elsevier Inc.


Turki A.,Laboratoire Of Chimie Des Materiaux Et Catalyse | Guillard C.,CNRS Research on Catalysis and Environment in Lyon | Dappozze F.,CNRS Research on Catalysis and Environment in Lyon | Berhault G.,CNRS Research on Catalysis and Environment in Lyon | And 3 more authors.
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2014

1D-TiO2 nanomaterials (nanotubes, nanorods, nanoplates, nanospheres and nanoparticles) with tuned structural and textural properties have been evaluated in the photocatalytic degradation of formic acid (FA) under UV conditions. The FA adsorption isotherms follow the model of Langmuir and the kinetic of FA photodegradation shows Langmuir-Hinshelwood model whatever the TiO2 morphologies. TiO2 nanotubes (HTNT-400), nanoplates (HTNW-700) and nanoparticles (HTNT-500 and HTNT-600) show an interesting photocatalytic activities compared to TiO2 nanospheres (P25) and nanorods (TNR). The nanotubular TiO2 (HTNT-400) has a photocatalytic activity 4 times higher than TiO2 P25. The enhanced activity is attributed to the smaller crystallite size of anatase and tuned surface area of the photocatalyst. The pH study showed that the coexistence of HCOO- and HCOOH species at natural pH (ca. 3.5) is favourable for better adsorption on active sites of titanium oxide nanomaterials and consequently to a better photocatalytic activity. © 2014 Elsevier B.V.


Kochkar H.,Center National Of Recherches En Science Des Materiaux Cnrsm | Aouine M.,CNRS Research on Catalysis and Environment in Lyon | Ghorbel A.,Laboratoire Of Chimie Des Materiaux Et Catalyse | Berhault G.,CNRS Research on Catalysis and Environment in Lyon
Journal of Physical Chemistry C | Year: 2011

Shape-controlled silver and palladium nanoparticles were for the first time synthesized by seed-mediated techniques in the presence of β-cyclodextrin (β-CD). Palladium and silver seeds were prepared by reduction of palladium or silver ions with sodium borohydride in the presence of sodium citrate dihydrate as a stabilizer. Seeds were then injected into a "growth" solution containing the same Pd (or Ag) precursor, ascorbic acid (as a weak reducing agent), and β-CD. Using β-cyclodextrin impacts the final morphology of silver nanoparticles through a strong capping effect slowing down the growth regime and shifting it to thermodynamiccontrolled conditions. Adjusting the β-CD/Ag molar ratio can lead to the selective formation of multiply twinned icosahedral particles presenting mainly {111} facets. On palladium, β-cyclodextrin selectively led to the controlled aggregation of primary nanoparticles into nanodendrites or multipods. After deposition on TiO 2, these nanostructured Pd catalysts show excellent activity for the hydrogenation of cinnamaldehyde. © 2011 American Chemical Society.


Turki A.,Tunis el Manar University | Guillard C.,CNRS Research on Catalysis and Environment in Lyon | Dappozze F.,CNRS Research on Catalysis and Environment in Lyon | Ksibi Z.,Tunis el Manar University | And 3 more authors.
Applied Catalysis B: Environmental | Year: 2015

Anisotropic TiO2 nanomaterials (nanotubes, nanorods, nanoplates, nanospheres, and nanoparticles) with controlled structural and textural properties have been evaluated in the photocatalytic degradation of phenol under UV conditions. The kinetic study of phenol adsorption fits well to a quasi-second-order model whereas the adsorption isotherms of phenol over the different TiO2 nanomaterials follow the Langmuir model and the degradation kinetics the Langmuir-Hinshelwood (L-H) model. TiO2 nanomaterials exposing (001) or (101) anatase facets are less active than TiO2 P25 for the phenol degradation. This is related to their tendency to degrade faster intermediates products (organic acids) rather than phenol itself. A good compromise between anatase crystallinity, crystallites sizes, and specific surface area can however improve the photocatalytic activity of the TiO2 nanomaterials. Results also showed that the degradation mechanism follows pseudo-first order kinetics. Pseudo-rate constants were therefore determined and formal mechanism schemes proposed. © 2014 Elsevier B.V.


Sdiri A.,University of Tsukuba | Higashi T.,University of Tsukuba | Hatta T.,Japan International Research Center for Agricultural science | Jamoussi F.,Center National Of Recherches En Science Des Materiaux Cnrsm | Tase N.,University of Tsukuba
International Journal of Global Environmental Issues | Year: 2012

This study focused on the removal of Pb(II), Cd(II), Cu(II), and Zn(II) using reagent solutions by natural limestone in a batch system. The sorbent, collected from the Late Cretaceous limestone beds, Tunisia, was characterised by X-ray diffraction (XRD), chemical analysis (XRF) and infrared spectroscopy (FTIR). XRF showed that the studied limestone contained high amount of calcium carbonates. XRD confirmed the presence of quartz along with the sharp peaks of calcite. FTIR spectra indicated that limestone was mainly composed of calcite, confirming the results of XRD and XRF analyses. Preliminary adsorption tests indicated that high removal efficiency could be achieved by limestone. The presence of impurities enhanced the adsorption capacity. Kinetic experiments showed that the sorption of metal ions best fitted the second order kinetic model with equilibration time of 60 min. These results suggested that the Campanian-Maastritchian limestone could be used for the removal of toxic metals from wastewaters. Copyright © 2012 Inderscience Enterprises Ltd.

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