Ibrahim S. Ahmed

A novel synthetic route for magnesium aluminate (MgAl2O4) nanoparticles using sol–gel auto combustion method and their photocatalytic properties

In this paper a novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed. Magnesium aluminate photocatalyst was synthesized via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350°C. Subsequently, the burnt samples were calcined at different temperatures. The pure spinel MgAl2O4 with average crystallite size 27.7, 14.6 and 15.65nm was obtained at 800°C calcinations using the aforementioned fuels, respectively. The obtained samples were characterized by powder X-ray diffraction, Fourier transform infrared, UV-Vis spectroscopy, transmission electron microscope, scanning electron microscope. The photo catalytic activity of MgAl2O4 product was studied by performing the decomposition of Reactive Red Me 4BL dye under UV illumination or sunlight irradiation. The dye considerably photocatalytically degraded by 90.0% and 95.45% under UV and sunlight irradiation, respectively, within ca. 5h with pseudo first order rate constants of 5.85×10(-3) and 8.38×10(-3)min(-1), respectively.

A controlled, template-free, and hydrothermal synthesis route to sphere-like α-Fe2O3 nanostructures for textile dye removal

Iron carbonate nanospheres were synthesized via hydrothermal treatment of aqueous solutions of iron sulfate, ascorbic acid and ammonium carbonate with a molar ratio of 1:1:3, respectively, at 140 °C for 1.5 h. Pure α-Fe2O3 nanoparticles with an average crystallite size of 10.5–32 nm were produced by thermal decomposition of FeCO3 at 400–600 °C for 2 h. The compositions of the products were identified by means of XRD, FE-SEM, HR-TEM, FT-IR, BET, zeta potential and thermal analysis. The adsorption properties of α-Fe2O3 were evaluated using reactive red 195 (RR195) dye. Various parameters influencing the adsorption process were investigated, using a batch technique. The results show that α-Fe2O3 nanoparticles show good adsorption capacity and the dye removal percentage reaches about 98.77% in 10 min. Plus, increasing the surface area of the α-Fe2O3 nanoparticles from 107.7 to 165.6 m2 g−1 increases the adsorption capacity from 4.7 to 20.5 mg g−1. Moreover, the adsorption data fit the Langmuir isotherm model well and the thermodynamic parameters exhibited an endothermic and spontaneous nature for the adsorption of RR195 dye on the hematite adsorbent.

Utility of oxidation/reduction reaction for the determination of ranitidine hydrochloride in pure form, in dosage forms and in the presence of its oxidative degradates

Three simple, accurate and sensitive colorimetric methods (A, B and C) for the determination of ranitidine HCl (RHCl) in bulk sample, in dosage forms and in the presence of its oxidative degradates are described. The first method A is based on the oxidation of the drug by N-bromosuccinimide (NBS) and determination of the unreacted NBS by measurement of the decrease in absorbance of amaranth dye (AM) at a suitable lambda(max)=520 nm. The methods B and C involve the addition of excess Ce(4+) and determination of the unreacted oxidant by decrease the red color of chromotrope 2R (C2R) at a suitable lambda(max)=528 nm for method B or decrease the orange pink color of rhodamine 6G (Rh6G) at a suitable lambda(max)=526 nm for method C. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 0.2-3.6, 0.1-2.8 and 0.1-2.6 microg ml(-1) for methods A, B and C, respectively. The apparent molar absorptivity. Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.3-3.4, 0.2-2.6 and 0.2-2.4 microg ml(-1) for methods A, B and C, respectively. Analyzing pure and dosage forms containing RHCl tested the validity of the proposed methods. The relative standard deviations were </=1.38 with recoveries 98.9-101.0%.

Synthesis and spectral characterization of CoxMg1−xAl2O4 as new nano-coloring agent of ceramic pigment

New nano-blue ceramic pigments of Co(x)Mg(1-x)Al(2)O(4) (0< or =x< or =0.1) have been prepared by co-precipitate-combustion as a hybrid method using urea as a fuel at 500 degrees C in open furnace in air atmosphere. The structure of pigment is assigned based on TGA/DTA/DrTGA analyses, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Also, electronic spectra, infrared (IR) and diffuse reflectance spectroscopy (DRS) using CIE L*a*b* parameter measurement techniques were used. The results revealed that the nano-particle size of pigments were obtained in the range 30-38 nm as well as the varying colors and particle size as a result of different calcinations temperatures within the range of 500-1200 degrees C for 2h.

Synthesis, solvatochromaticity and bioactivities of some transition metal complexes with 2-(R-benzylideneamino)-pyridin-3-ol Schiff base derivatives.

New four Schiff bases are prepared by condensation of 2-amino-pyridin-3-ol with 3, 4-dihydroxy-benzaldehyde (I), 2-hydroxybenzaldehyde (II), 5-bromo-2-hydroxybenzaldehyde (III), and 4-dimethylaminobenzaldehyde (IV). The structures of these compounds are characterized based on elemental analyses (C. H. N), IR and (1)H NMR. Also, the electronic absorption spectra are recorded in organic solvents of different polarity. The solvents are selected to be covered a wide range of parameters (refractive index, dielectric constant and hydrogen bonding capacity). The UV-vis absorption spectra of Schiff base compounds are investigated in aqueous buffer solutions of varying pH and utilized for the determination of ionization constant, pK(a) and activation free energy, DeltaG(*) of the ionization process. The biological activity against bacterial species and fungi as microorganisms representing different microbial categories such as (two Gram-negative bacteria, Eschericha coli and Agrobacterium sp.),three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtlus and Bacillus megatherium), yeast (Candida albicans), and fungi (Aspergillus niger) were studied.

SPECTROPHOTOMETRIC DETERMINATION OF FAMOTIDINE THROUGH OXIDATION WITH N-BROMOSUCCINIMIDE AND CERRIC SULPHATE

ABSTRACT Three simple, accurate, sensitive and selective spectrophotometric methods (A, B and C) for the determination of famotidine (Fam) in bulk sample, in dosage forms and in the presence of its oxidative metabolites are described. The first method A is based on oxidation of the drug by N-bromosuccinimide (NBS) and determination of the unreacted NBS by measuring the decrease in absorbance of Amaranth dye (AM) at a suitable λmax (521 nm). The methods B and C involve addition of excess cerric sulphate and determination of the unreacted Ce(IV) by decrease the red colour of chromotrope 2R (C2R) at λmax 528 nm for method B or decrease the orange pink colour of rhodamine 6G (Rh6G) at λmax 526 nm for method C. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 0.1–2.4 µg mL−1 for method A and 0.1–2.2 µg mL−1 for methods B and C. The apparent molar absorptivity, Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.2–2.2 µg mL−1 for method A and 0.2–2.0 µg mL−1 for methods B and C. The stoichiometric ratio between the drug (Fam) and the oxidant (NBS or Ce4+) was estimated. The validity of the proposed methods were tested by analysing pure and dosage forms containing famotidine and in the presence of its oxidative degradates. Statistical treatment of the results reflects that the proposed procedures are precise, accurate and easily applicable for the determination of famotidine in pure form, in pharmaceutical preparations and in the presence of its oxidative degradates.

SELECTIVE SPECTROPHOTOMETRIC DETERMINATION OF COBALT(II) IN SYNTHETIC MIXTURES AND PHARMACEUTICAL FORMULATES WITH 5-[o-CARBOXYPHENYLAZO]2,4-DIHYDROXYBENZOIC ACID

The present work describes a selective, rapid and economical method for the determination of cobalt(II) using 5-[o-carboxyphenylazo] 2,4-dihydroxybenzoic acid [CPDB] as a spectrophotometric reagent without heating or extraction. The CPDB reacts with Co(II) in presence of Tween 80 surfactant forming a pink complex of a stoichiometric ratio 1:2 absorbed maximally at 555 nm with stability constant amounting to 10.33. Beers law is obeyed for a concentration of at least 3.50 μg ml−1 with Sandell sensitivity of 3.6 ng cm−2and molar absorptivity of 1.64×104 l mol−1cm−1. The relative standard deviation for six replicate sample of 2.0 μg ml−1 is 1.11%. A selective procedure is proposed for cobalt determination in presence of different metal ions in synthetic mixtures and in pharmaceutical formulations with more accurate results.

Mono and binuclear Ag(I), Cu(II), Zn(II) and Hg(II) complexes of a new azo-azomethine as ligand: synthesis, potentiometric, spectral and thermal studies.

New azo-azomethine dyes were prepared by reaction of p-aminobenzoic acid, o-anisidine, o-nitroaniline, and p-bromoaniline with salicylaldehyde respectively to form azo compounds and then condensation by urea to form 4-(R-arylazo 2-salicylaldene)-urea azo-azomethine derivatives (I(a-d)). The complexes of these ligands with Ag(I), Cu(II), Zn(II) and Hg(II) metal ions were prepared. The structure of the free ligands and their complexes were characterized by using elemental analysis (C, H, N), (1)H NMR, IR and UV-Vis-spectra. The proton dissociation constants of the ligands and the stability constant of their complexes have been determined potentiometrically in 40% (v/v) alcohol-water medium as well as the stoichiometry of complexes were determined conductometrically. The data reveal that the stoichiometries for all complexes were prepared in molar ratios (1:1) and (1:2) (M:L). The electrolytic and nonelectrolytic natures of the complexes were assigned based on molar conductance measurements. The thermogravimetric (TG), and differential thermal analyses (DTA) were studied in nitrogen atmosphere with heating rate 10°C/min. The kinetic and thermodynamic parameters for thermal decomposition of complexes have been calculated by graphical method using Coats-Redfern (CR) method.

Selective Spectrophotometric Investigation and Determination with Some Thiazolylazo Compounds, of Palladium(II), or of Tartaric Acid in the Presence of Niobium(V)

Abstract Spectrophotometric investigation of palladium(II) or of tartaric acid in presence of niobium(V) were conducted using their colour reactions with 5‐(benzothiazolyl‐azo)2,5‐naphthalenediol (I), 1‐(2‐benzothiazolylazo)2‐hydroxy‐3‐naphthoic acid (II) and 5‐(2‐benzothiazolylazo)8‐hydroxyquinoline (III) in acidic medium, or weak acidic medium. The stoichiometric ratios and stability constants of the formed complexes were determined. The calibration graphs were linear in the range of 0.02–1.35, 0.02–1.20, and 0.02–1.10 µg mL−1 of Pd2+ with apparent molar absorptivities of 6.15 × 104, 7.27 × 104 and 5.80 × 104, L mol−1 cm−1 using I, II, and III, respectively, at λmax 638, 677, and 656 nm. On the other hand, calibration graphs for tartaric acid in the presence of Nb5+ were linear in the 0.01–1.60, 0.01–1.7, and 0.01–1.45 µg mL−1 range with ϵ of 1.27 × 105, 1.13 × 105, and 1.45 × 105 L mol−1 cm−1 at 692, 649, and 661 nm, respectively. Sandell sensitivity, detection, and quantification limits were also calculated. The proposed methods were selective and sensitive in comparison with other methods and the effect of foreign ions Cu2+, Ni2+, and Fe2+ was negligible for the assay of Pd2+.

Synthesis, thermal and spectral characterization of nanosized NixMg1−xAl2O4 powders as new ceramic pigments via combustion route using 3-methylpyrozole-5-one as fuel

New Ni(x)Mg(1-x)Al(2)O(4) nanosized in different composition (0.1≤x≤0.8) powders have been synthesized successively for first time by using low temperature combustion reaction (LTCR) of corresponding metal chlorides, carbonates and nitrates as salts with 3-methylpyrozole-5-one (3MP5O) as fuel at 300°C in open air furnace. Magnesium aluminate spinel (MgAl(2)O(4)) was used as crystalline host network for the synthesis of nickel-based nano ceramic pigments. The structure of prepared samples was characterized by using different techniques such as thermal analysis (TG-DTG/DTA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). UV/Visible and Diffuse reflectance spectroscopy (DRS) using CIE-L*a*b* parameters methods have been used for color measurements. The obtained results reveal that Ni(x)Mg(1-x)Al(2)O(4) powder of samples is formed in the single crystalline and pure phase with average particle size of 6.35-33.11 nm in the temperature range 500-1200°C. The density, particle size, shape and color are determined for all prepared samples with different calcination time and temperature.