The inhibition performance of phenazopyridine tablet on mild steel in 0.5 M phosphoric acid and 1M hydrochloric acid solutions is investigated using different techniques (potentiodynamic polarization, electrochemical impedance spectroscopy (EIS)) and scanning electronic microscopy (SEM)). The gained results demonstrated that various concentrations of phenazopyridine inhibited the corrosion of the alloy in both of the acid solutions. The inhibition efficiency raised with a rise in the concentration of the drug and reduced with a rise in temperature. The maximum inhibition efficiency is observed in the presence of 500 ppm of the compound. Polarization evaluations displayed that the phenazopyridine acts as a mixed inhibitor in the hydrochloric acid solution and acts as an anodic inhibitor in the phosphoric acid solution. The corrosion parameters derived from the techniques are agreeing with one another. The adsorption mechanism of the tablet on the alloy was investigated by the Langmuir adsorption isotherm. The entropy of adsorption increased in hydrochloric acid and decreased in phosphoric acid solution. SEM micrographs were taken from the surface of the mild steel after exposure.
The symmetrical and asymmetrical electrodes made of Mg were studied in 0.1-M NaCl electrolyte adjusted at pH 12. The statistical and wavelet methods were employed for analyzing the electrochemical current noise (ECN) signals. The asymmetric configuration was used for electrochemical detection of filiform corrosion on Mg electrode. The real time scale of the dominant transients of the asymmetric electrodes was detected on the basis of the maximum peak in the SDPS plots. The SDPS values of the real time scale crystals of the ECN signals resulting from asymmetrical electrodes increased with the increase in immersion time due to the onset of filiform corrosion.
Asymmetric Configuration (As-Co) in the electrochemical noise (EN) was used to evaluate Ranunculus Arvensis / silver nanoparticles (RA/Ag NPs) as corrosion inhibitor for aluminum alloy (AA 2030) when gets exposed to 3.5% NaCl media. The ECN results of Asymmetric Configuration (As-Co) and Symmetric Configuration (Sy-Co) were interpreted using wavelet and statistical methods. The standard deviation of partial signal (SDPS) plots derived using of wavelet. The SDPS plot of As-Co demonstrated that the quantity of electric charge (Q) decreased with the addition of the inhibitor up to the optimum amount (200 ppm) due to the decreased corrosion rate. Moreover, the use of As- Co leads to record signal of one electrode and prevent recording extra signals arising from two identical electrodes which confirmed by the statistical parameters. The As-Co made of Al alloys were more satisfactory for estimating inhibiting effect of RA/Ag NPs compared to Sy-Co. Besides, aqueous extract of Ranunculus Arvensis (RA) plant as reducing agent mediates the synthesis of silver nanoparticles (RA/Ag NPs). The prepared NPs have been elaborately characterized using Field-Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD) analysis, and Fourier-Transform Infrared Spectroscopy (FT-IR) that revealed suitable synthesize of the RA/Ag NPs.
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