Inhibitory Properties of Neomycin Thin Film Formed on Carbon Steel in Sulfuric Acid Solution: Electrochemical and AFM Investigation

Abstract

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.

Anticorrosive coating based on poly(vinyl acetate) formed by electropolymerization on the copper surface

“…More suggestive are the Bode diagrams [Figure (b)], which show that the phase angle maximum is significantly lower (−33.2°) in the case of the copper coated with PVAC (Cu/PVAC/HCl) than that of Cu/SE/HCl sample (−25.2°). This indicates a completely modified surface by PVAC adsorption compared to copper surface modified by adsorption of some corrosion products . In the case of the standard, the phase angle maximum was shifted to lower frequencies and it has a comparative value, around −28.7°, with that of Cu/SE/HCl sample.…”

“…The polarization resistance ( R p ) was determined from the linear diagram shown in Figure (b) plotted in the potential range very close to the corrosion potential (±30 mV). The slopes of straight lines represent 1/ R p . According to equations inserted in Figure (b), it is noted that the copper coated with PVAC has the highest polarization resistance, which denotes polymer inhibition capacity.…”

“…The slopes of straight lines represent 1/R p . 2,30 According to equations inserted in Figure 3(b), it is noted that the copper coated with PVAC has the highest polarization resistance, which denotes polymer inhibition capacity. The main electrochemical parameters were computed using the VoltaMaster 4 software and are listed in Table III.…”

“…Surface adherent thin films can improve some features of metallic materials such as optical, mechanical properties as well as their corrosion resistance in different aggressive media . The organic films with inhibitory properties interpose at the material/electrolyte interface reducing the oxidation processes, thereby restricting the corrosion upon metals‐environment contact.…”

“…Surface adherent thin films can improve some features of metallic materials such as optical, mechanical properties as well as their corrosion resistance in different aggressive media. [1][2][3][4][5][6] The organic films with inhibitory properties interpose at the material/electrolyte interface reducing the oxidation processes, thereby restricting the corrosion upon metals-environment contact. In addition, these can have an electrocatalytic effect on the decomposition reactions of some compounds which pollute the industrial environments and wastewaters, being used to prepare specific electrodes for decontamination of the respective media.…”