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The inhibitory impacts of two expired drugs, namely, azithromycin (AZM) and roxithromycin (RXM) towards the corrosion of mild steel (MS) in 1.0 M H2SO4 solution were examined exploiting potentiodynamic polarization, electrochemical impedance spectroscopy and weight loss techniques. The results obtained from various employed techniques indicate that increasing the concentration of examined expired drugs and reducing the temperature increased the inhibition efficiencies. Potentiodynamic polarization indicated that the expired AZM and RXM drugs acted as mixed-type inhibitors, but the cathode was highly polarized, βc > βa. The inhibiting power of these compounds is interpreted based on their adsorption on the surface of MS. The adsorption process obeys Langmuir isotherm. Impedance data confirmed that MS corrosion is under charge transfer control and the adsorption of both expired drugs on the MS surface led to the formation of protective film. The inhibition efficiency of RXM is greater than that of AZM due to the increased molecular weight and number of electron donating group within the expired drug. Activation and adsorption thermodynamics parameters were computed and interpreted. The adsorption process is spontaneous and endothermic. [ABSTRACT FROM AUTHOR]

The inhibition impacts of two novel synthesized green biosurfactants (B-Surf.), namely, sodium N-dodecyl asparagine (AsS) and sodium N-dodecyl arginine (ArS), on the dissolution of mild steel alloy (MS-37-2), in aqueous sodium chloride solutions was inspected using various techniques. Increased concentration of NaCl solution resulted in an increase in the corrosion rate of MS-37-2. Inhibition efficiencies of B-Surf. compounds were found to increased with increase inhibitor concentrations. The synergistic inhibition action between B-Surf. inhibitors and Zn2+, Al3+ and Ce4+ on the dissolution behavior of steel alloy in NaCl solutions was investigated and interpreted. The surface morphology of the MS-37-2 surface was observed using a scanning electron microscopy (SEM). This adsorption follows Langmuir isotherm. The evaluated thermodynamic functions supported the mechanism of physical adsorption of the inhibitors. The mechanisms of corrosion and its inhibition of MS-37-2 in NaCl solutions were interpreted. [ABSTRACT FROM AUTHOR]

In the present work, Mn3O4 was prepared by various methods and successfully loaded with metallic Au nanoparticles reduced by hydrazine hydrate using microwave irradiation (MWI) method. The surface morphology and composition of the prepared samples were characterized with X-ray diffraction (XRD), N2 adsorption–desorption, temperature programmed reduction (H2-TPR), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that no significant changes in some textural and structural properties of the samples due to preparation method or Au nanoparticles deposition. While the surface composition and reducibility of the samples were greatly affected by preparation method and Au deposition. The CO oxidation reaction over the samples was selected as a model reaction to study the relation between surface properties of the samples and their catalytic performance. The results showed that a direct proportionality exists between the reducibility and the CO oxidation activity of catalysts. The kinetic study of the reaction showed that the reaction is first order. Moreover, the samples exhibited good stability in CO oxidation at 100% conversion for around 30 h under the reaction conditions. [ABSTRACT FROM AUTHOR]

The inhibiting impact of natural aqueous extracts of some plants such as curcumin, parsley and cassia bark extracts for the corrosion of carbon steel (C-steel) in 0.5 M H2SO4 solution was inspected utilizing some techniques such as galvanostatic and potentiodynamic anodic polarization and weight loss measurements. Outcomes indicated that the percentage inhibition efficiency increases with increasing the concentration of the extract due to its horizontal adsorption on the C-steel surface. The process of adsorption is followed by the Temkin isotherm. These natural extracts acted as pitting corrosion inhibitors by shifting the pitting potential to more noble values. The sequence of inhibition efficiency of the natural extracts decreases in the following order: cassia bark extract > parsley extract > curcumin extract. This arrangement is related to the molecular size of the major components of the three natural extracts used. [ABSTRACT FROM AUTHOR]

In this work, a series of gold nanoparticles deposited on α-FeOOH nanorods were studied in relation to their performance in the low-temperature oxidation of CO. The catalysts were characterised by different techniques such as, Fourier transform infrared (FTIR), X-ray diffraction (XRD), N2adsorption/desorption, hydrogen temperature programmed reduction (H2-TPR) and transmission electron microscope (TEM) images. The XRD proved the formation of α-FeOOH crystalline structure and also showed small diffraction peaks for Au-agglomerated particles on the surface. While TEM images revealed the formation of α-FeOOH with nanorod structure with different dimensions, TEM also showed some agglomerations of Au particles on the support surface. The H2-TPR experiments the enhancement of Au/α-FeOOH reducibility. The performance of Au/α-FeOOH in the CO oxidation was greatly affected by Au content and α-FeOOH preparation method. [ABSTRACT FROM PUBLISHER]