Norah Alhokbany

Chitosan based polymer matrix with silver nanoparticles decorated multiwalled carbon nanotubes for catalytic reduction of 4-nitrophenol

A novel catalyst for the reduction of 4-nitrophenol (4-NP) was prepared using carboxyl group-functionalized multiwalled carbon nanotubes (MWCNTs), polymer matrix, and silver nanoparticles (AgNPs). The AgNPs were prepared by the reduction of silver nitrate by trisodium citrate in the MWCNTs-polymer nanocomposite; the size of the synthesized AgNPs was found to be 3nm (average diameter). The synthesized nanocomposites were characterized using several analytical techniques. Ag@MWCNTs-polymer composite in the presence of sodium borohydride (NaBH4) in aqueous solution is an effective catalyst for the reduction of 4-NP. The apparent kinetics of reduction has a pseudo-first-order kinetics, and the rate constant and catalytic activity parameter were found to be respectively 7.88×10(-3)s(-1)and 11.64s(-1)g(-1). The MWCNTs-polymer nanocomposite renders stability to AgNPs against the environment and the reaction medium, which means that the Ag@MWCNTs-polymer composite can be re-used for many catalytic cycles.

Macroporous natural capsules extracted from Phoenix dactylifera L. spore and their application in oral drugs delivery

Macroporous natural sporopollenin exine capsules (SEC) were extracted from date palm (Phoenix dactylifera L.) and coated by natural polymer composite (carboxymethyl cellulose with epichlorohydrin). The polymer coated exine capsules (PCEC) were used in in-vitro investigations for controlled delivery of paracetamol. SEC, PCEC, and drugs loaded capsules (PCEC-PAR) were characterized by scanning electron microscope (SEM), surface area (BET), Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The length of SEC was found to be 20-20.5 μm, and the pore sized was 50-135 nm, as measured using SEM. The studies revealed that maximum loading of the drug was at pH 6.0 (97.2%, with 50 mg mL(-1)). The results indicate that by increasing the pH from 1.4 to 7.4, the cumulative release rates of paracetamol in physiological buffer solution (PBS) is more than two times as in simulated gastric fluid (SGF). In addition, the in-vitro toxicity of PCEC against Caco-2 cells was tested by the 3-[4,5-dimethylthiazole-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay, and the results revealed that PCEC are biocompatible materials. The overall results encourage further studies on the clinical use of PCEC as drug carriers.

Radiation induced synthesis of In2O3 nanoparticles - part 1: synthesis of In2O3 nanoparticles by sol-gel method using un-irradiated and γ-irradiated indium acetate

Pure phase of In2O3 nanoparticles were synthesized by sol-gel method in non-aqueous medium using un-irradiated and γ-irradiated indium acetate precursors. The as-prepared In2O3 nanoparticles were characterized by XRD, FT-IR, SEM, TEM and TG techniques. The results showed that pre-irradiation to indium acetate with 102 KGy γ-ray absorbed dose has significant effects on the shape and size of the as-synthesized In2O3 nanoparticles. In case of un-irradiated precursor, the SEM images show agglomerated and disordered spherical nanoparticles. In γ-irradiated case the particles showed coral-like structure. The as-synthesized In2O3 nanoparticles prepared using γ-irradiated precursor showed higher thermal stability compared with those prepared using un-irradiated one. The results were discussed in view of the role of γ-irradiation on the morphology and thermal behavior of In2O3 nanoparticles.

Synthesis, characterization, multifunctional electrochemical (OGR/ORR/SCs) and photodegradable activities of ZnWO 4 nanobricks

AbstractBrick-shaped zinc tungstate nanoparticles have been synthesized by ecofriendly solvent-free process using molten salts. Zinc tungstate nanobricks (ZnWO4 Nbs) were characterized by powder x-ray diffraction (PXRD), FTIR, Raman, energy dispersive and electron microscopic studies. ZnWO4 Nbs are used as the multifunctional electrode materials to oxygen generation reactions (OGR), oxygen reduction reactions (ORR) and supercapacitors (SCs) as well as photo-catalysts in the waste-water treatment by the degradation of organic dyes. Low overpotential (ƞ10 = 0.475 V), low tafel slope (140 mV/dec), high current density (~70 mA/cm2) and good stability of the electrodes are the key results of the present studies for water electrolysis (OGR/ORR). ZnWO4 Nbs have also shown great interest in supercapacitors with efficient charge–discharge activities in 1 M KOH. The specific capacitance and energy density of ZnWO4 Nbs were found to be 250 F/g and 80 Wh/kg, respectively, at 5 mV/s, these values are relatively higher than that of previously reported specific capacitance and energy density value of metal tungstate nanoparticles. ZnWO4 Nbs as the photo-catalysts work very significantly for photocatalytic degradation of aqueous MB dye solution (~85 % in 3 h) in neutral medium. ZnWO4 Nanobricks show significant multifunctional electro-chemical activities in alkaline medium and photocatalytic degradation of organic dye in neutral medium.HighlightsEcofriendly solvent-free Synthesis of ZnWO4 Nanobricks (Nbs).ZnWO4 Nbs show admirable multifunctional electrochemical activities (OGR/ORR/SCs).Low overpotential, low Tafel values, relatively high current density and good stability of electrode materials are significant for OGR and ORR.ZnWO4 Nbs exhibit efficient supercapacitor performances with the specific capacitance (250 F/g) and energy density (80 Wh/kg) at 5 mV/s in 1 M KOH.ZnWO4 Nbs also work as photo-catalysts to enhance the degradation of aqueous organic dyes.

Synthesis and characterization of hybrid nanocomposites as highly-efficient conducting CH4 gas sensor

Functionalized (MWCNTs-COOH), non-functionalized multiwalled carbon nanotubes (MWCNTs) and polyaniline (PANI) based conducting nanocomposites (PANI/polymer/MWCNTs and PANI/polymer/MWCNTs-COOH) have been prepared in polymer matrix. The prepared nanocomposites were characterized via FTIR, TGA, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was observed that the prepared conducting nanocomposites show excellent sensing performances toward CH4 at room temperature and both the response and recovery time were recorded at around 5s, respectively, at the room. The PANI/polymer/MWCNTs based detector had quicker/shorter response time (<1s), as well as higher sensitivity (3.1%) than that of the PANI/polymer/MWCNTs-COOH based detector. This was attributed to nonconductive -COOH that results in a poor sensitivity of PANI/polymer/MWCNTs-COOH-based prototype. The PANI/polymer/MWCNTs-COOH nanocomposites show almost 10 time higher sensitivity at higher temperature (60°C) than that at room temperature.

Radiation Induced Synthesis of In2O3Nanoparticles - Part II: Synthesis of In2O3 Nanoparticles by Thermal Decomposition of Un-irradiated and γ-irradiated Indium Acetylacetonate

Pure cubic phase, In2O3 nanoparticles with porous structure were synthesized by solid state thermal oxidation of un-irradiated and γ-irradiated indium acetyl acetonate in presence and absence of sodium dodecyl sulphate as surfactant. The as- synthesized In2O3nanoparticles were characterized by X-ray diffraction (XRD), fourier transformation infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transition electron microscopy (TEM) and thermogravimetry (TG). The shapes and morphologies of as- synthesized In2O3nanoparticles were highly affected by γ-irradiation of indium acetyl acetonate precursor and by addition of sodium dodecyl sulphate as surfactant. Calcination of un-irradiated indium acetyl acetonate precursor to 4 hours of 600 °C leads to the formation of spherical- shaped accumulative and merged In2O3 nanoparticles with porous structure, whereas irregular porous architectures composed of pure In2O3nanoparticles were obtained by using γ-irradiated indium acetylacetonate precursor. The as- prepared In2O3 nanoproducts exhibit photoluminescence emission (PL) property and display thermal stability in a wide range of temperature (25-800 °C) which suggest possible applications in nanoscale optoelectronic devices.

Micelle-Assisted Strategy for the Direct Synthesis of Large-Sized Mesoporous Platinum Catalysts by Vapor Infiltration of a Reducing Agent

Stable polymeric micelles have been demonstrated to serve as suitable templates for creating mesoporous metals. Herein, we report the utilization of a core-shell-corona type triblock copolymer of poly(styrene-b-2-vinylpyridine-b-ethylene oxide) and H2PtCl6·H2O to synthesize large-sized mesoporous Pt particles. After formation of micelles with metal ions, the reduction process has been carried out by vapor infiltration of a reducing agent, 4-(Dimethylamino)benzaldehyde. Following the removal of the pore-directing agent under the optimized temperature, mesoporous Pt particles with an average pore size of 15 nm and surface area of 12.6 m2·g−1 are achieved. More importantly, the resulting mesoporous Pt particles exhibit superior electrocatalytic activity compared to commercially available Pt black.