Shawky M. Hassan

Preparation, characterization and pH-metric measurements of 4-hydroxysalicylidenechitosan Schiff-base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ru(III), Rh(III), Pd(II) and Au(III)

The 4-hydroxysalicylidenechitosan Schiff-base (2CS-Hdhba) was prepared by the condensation of 2,4-dihydroxybenzaldehyde with chitosan, and its metal complexes, [M(2CS-dhba)Cl(2)(H(2)O)(2)] (M(III)=Fe, Ru, Rh), [M(2CS-dhba)(AcO)(H(2)O)(2)] (M(II)=Co, Ni, Cu, Zn), [Pd(2CS-dhba)Cl(H(2)O)] and [Au(2CS-dhba)Cl(2)], are reported. These complexes were characterized by elemental analysis, by spectral data (FTIR, solid-phase (13)C NMR, UV-vis and ESR spectroscopy), by morphological observations (SEM and XRD), and by magnetic and thermal measurements. The Schiff base (2CS-Hdhba) behaves as a bidentate chelate with a single negative charge. The azomethine nitrogen and the deprotonated 2-hydroxy centres with the pendant glucosamine hydroxy functionality play no role in coordination. The dissociation constants of 2CS-Hdhba and the stability constants of some of its metal complexes have been determined pH-metrically.

Studies on the inhibition of aluminium dissolution by some hydrazine derivatives

Abstract The inhibitive effect of some hydrazine derivatives on the dissolution of aluminium in 2N hydrochloric acid solutions has been studied. The volume of the hydrogen evolved was followed as a function of time and the corresponding rates of dissolution were determined. The inhibition efficiencies of the hydrazine derivatives were evaluated as the percentage reduction in reaction rate. The obtained results are found to be in good agreement with those given by the thermometric and weight loss methods. Adsorption of the studied hydrazine derivatives occurs in one step as a monolayer of the adsorbate on the metal surface, with the exception of diformyl hydrazide. The results indicate that the adsorption of hydrazine derivatives occurs over the aluminium surface through their carbonyl group.

The effect of some B-diketo compounds on the retardation of aluminium dissolution in HCl

Abstract The inhibitive action of some B-diketo compounds on the dissolution of aluminium in 2M HCl has been investigated by hydrogen evolution, thermometric and weight loss techniques. The adsorbability of inhibitors is dependent on the basicity of the oxygen and nitrogen sites involved. The dissolution reaction of aluminium in hydrochloric acid solutions is zero order and remains so when B-diketo compounds are present. The rate constant decreases as the inhibition efficiency increases. The activation energy of the dissolution reaction increases with decreasing acid concentration and increasing inhibitor concentration. Values of the Arrhenius activation energies agree with those obtained for an activation controlled process.

Photodegradation of organic compounds using chromium oxide-doped nano-sulfated zirconia

ZrO2 is considered a huge-gap semiconductor (band gapxa0≈xa05xa0eV). To improve the visible-light photocatalytic activities of ZrO2, an efficient Cr, SO42− co-doped ZrO2 photocatalyst was synthesized by the simple impregnation method followed by calcination at different calcination temperatures (300, 400, 500, and 600xa0°C) for 3xa0h. The synthesized photocatalysts were characterized by x-ray diffraction, transmission electron microscopy analysis, scanning electron microscopy analysis, energy dispersive X-ray spectroscopy analysis, FT-IR spectroscopic technique, potentiometric titration and UV–Vis spectroscopy analysis. ZrO2 co-doped with Cr and SO42− shows more efficiency than SO42−-doped ZrO2 in several aspects like surface structure, decreasing electron–hole recombination and band gap energy. The photodegradation of methylene blue dye for SO42−-doped ZrO2 and Cr, SO42−-co-doped ZrO2 has been investigated. The photocatalytic reaction confirmed that the co-doped ZrO2 photocatalyst showed higher photocatalytic activity than mono-doped ZrO2.

Structure, texture and catalytic properties of Pd/SiO2 catalysts

The structural properties of Pd/silica catalysts have been investigated by means of DTA and X-ray techniques. The X-ray results indicate that Pd metal is the only phase formed. The textural properties were determined using low-temperature nitrogen adsorption. Surface areas were calculated and the dependence of the surface area on the metal content has been discussed. Pore structure analyses indicate the presence of both micro-and meso-pores. The dehydrogenation of cyclohexane was found to be affected by the metal content. The active site for the dehydrogenation process on Pd/silica catalysts consists of one Pd atom. The kinetics of the dehydrogenation exhibit a fractional order.