Abstract:Our study aims to implement a strategy to reduce the carbon steel corrosion rate in a sulfuric acid solution, using an expired drug with adsorption affinity on the metal surface. To investigate the corrosion protection efficiency of an environmental friendly inhibitor, namely neomycin sulfate (NMS), the electrochemical measurements were applied on carbon steel immersed in 1.0 M H 2 SO 4 solution with and without NMS. The protective layer that formed on the steel surface was studied by atomic force microscopy (AFM). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) showed that the presence of the neomycin sulfate in acid solution leads to the decrease in corrosion current density (i corr ) and the increase of polarization resistance (R p ). The mixed mechanism between physical and chemical adsorption of NMS molecules on the steel surface was proposed according to the Langmuir adsorption isotherm. AFM indicated that the NMS molecules contributed to a protective layer formation by their adsorption on the steel surface. The AFM parameters, such as root mean square roughness (R q ), average roughness (R a ), and maximum peak to valley height (R p−v ) revealed that in the presence of NMS a smoother surface of carbon steel was obtained, compared to the steel surface corroded in sulfuric acid blank solution.

The purpose of this paper is to study a possibility of reintroduction in circulation of the expired drugs, as ecological corrosion inhibitors that can have a decisive effect on decreasing of metallic corrosion rate. In this regard, we simultaneously present an overview on metronidazole drug performance, as corrosion inhibitor of three substrates in hydrochloric acid solution. The electrochemical measurements such as potentiodynamic polarization and electrochemical impedance spectroscopy were performed to determine the metronidazole inhibition efficiency that has reached the highest level for aluminum, followed by carbon steel and 304L stainless steel. To discuss the metronidazole action mechanism, UV-Vis spectrophotometry was applied to analyze the uninhibited and inhibited solutions, this showing that in the absence of metronidazole, the solutions were infested with higher amount of metal cations compared to those were inhibited with metronidazole. Corroborating the information, it can affirm that, the protective coatings were formed by overlapping of some processes like pure adsorption of metronidazole and electrostatic interactions for aluminum and, complementary for steels, the adsorption of their complexes with iron, helpful supports being El-Awady kinetic model and Temkin adsorption isotherm, respectively.

Metal complexes of Schiff base derived from different antibiotics are widely employed as biological active materials, especially as antibacterial agents. Two new metal (II) complexes with the Schiff, base (HL) derived from amoxicillin and salicylaldehyde were synthesized and investigated using elemental analysis, spectroscopic techniques (IR and UV-Vis), conductometric and magnetic measurements. The IR spectra illustrated a bidentate ligand which coordinates through phenolic oxygen atom and imino nitrogen atom from azomethine bond. UV-Vis spectrophotometry showed the characteristic adsorption bands corresponding to an octahedral geometry for both metal complexes. The general formula established from experimental data was found to be [ML 2 (H 2 O) 2 ] (M=Co(II) and Ni(II)). This composition was further confirmed by thermal analysis and their thermal stability in nitrogen atmosphere was investigated. Antibacterial study showed that the efficiency of metal complexes is higher than the one found for the free Schiff base ligand.

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