Attenuation of Mild Steel-Acid Corrosion Using Exfoliated Graphite Oxide-Polymer Composite: Synthesis, Characterization, Electrochemical, and Response Surface Method Approach

This work deals with the study of the anticorrosion behavior of a biopolymer, namely Guar Gum (GG) and its composite on mild steel (MS) in sulfamic acid (SA) solution using electrochemical techniques. GG was found to be a potential inhibitor relatively at its higher concentration and showed maximum inhibition efficiency (IE) of 74% at 3 g/L (3000 ppm). To improve its IE, exfoliated graphite oxide (xGO)/GG polymer composite was prepared, and its inhibition property was assessed in 1 M SA solution at different temperatures by weight loss method (WL). The chemical structure of xGO/GG polymer composite was examined by FT-IR, and the morphology was inspected by optical microscopy, scanning electron microscopy study, and energy dispersive spectroscopy technique. xGO/GG polymer composite emerged as an efficient corrosion inhibitor for MS as marked from the outcomes of the electrochemical investigations and showed improved IE of 93% at 0.6 g/L (600 ppm) when compared to GG. Experimental results found by WL measurements are used to evaluate the thermodynamic parameters at various temperatures. Further, a Box-Behnken composite design with three factors and three levels has been used to minimize the experimental conditions. The IE was enhanced with the increase in the inhibitor concentration as observed from the main effect plot. The maximum IE of 84.21% was projected by the response surface method (RSM) with temperature (A = 30 °C), inhibitor concentration (B = 600 ppm), and time (C = 1 h).

Electrochemical and quantum chemical study to assess the role of (2E)-2-(furan-2-ylmethylidene) hydrazine carbothioamide as inhibitor for acid corrosion of mild steel

Synthesis and inhibition effectiveness of (2E)-2-(furan-2-ylmethylidene) hydrazine carbothioamide (FMHC) as an inhibitor for corrosion of mild steel in 0.5 M H2SO4 is reported. Experiments were conducted at various temperatures (303–323 K) by adopting potentiodynamic polarization and electrochemical impedance spectroscopy. Readings obtained demonstrated that percentage inhibition efficiency (% IE) improved with the upsurge in the concentration of FMHC, while it decreased with a rise in temperature. The highest % IE observed was 60% for 2.5 × 10–4 M FMHC at 303 K. FMHC worked moderately as a mixed inhibitor. FMHC obeyed the Langmuir model of adsorption and the mode of adsorption was physisorption on the mild steel surface which was further endorsed by examining the surface using the scanning electron microscope. A clear insight into the mechanistic features of corrosion inhibition by using FMHC was acquired. Calculation of activation parameters helped to suggest an appropriate mechanism for the adsorption of FMHC on mild steel through quantum chemical calculations using density functional theory (DFT).

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Glycogen nanoparticles as a potential corrosion inhibitor

Biological macromolecules are proven to be potential green corrosion inhibitors because of their outstanding structural features and eco-friendliness. This study is aimed at enhancing their corrosion mitigation capabilities by converting them into nanoparticles. This is the first work where nanoparticles of biological macromolecules are exploited for corrosion mitigation studies. Glycogen nanoparticles (GLY-Np) were synthesized by microwave-mediated nanoprecipitation method and characterized by ATR-FTIR, XRD, UV-Visible Spectroscopy, FESEM analysis, EDX, TEM, and Zeta potential measurements. They are used as an eco-friendly inhibitor for corrosion control of zinc in sulfamic acid (NH₂SO₃H). The electrochemical study was a primary experimental tool employed for corrosion rate measurement. Conditions were optimized to obtain maximum inhibition efficiency by varying concentrations of inhibitor and temperature. Activation and thermodynamic parameters were evaluated and discussed in detail. A suitable adsorption isotherm was proposed to fit the experimental results. Adsorption of the inhibitor was confirmed by SEM, EDX, and AFM techniques. The inhibition efficiency of 92% was obtained for 0.02 gL^-1 GLY-Np. Thus, GLY-Np turned out to be an effective green inhibition with economic benefits.

The impact of naphthalimide derivative on the mitigation of mild steel corrosion in sulfamic acid medium: experimental and theoretical insights

The deterioration of iron-based alloys, especially mild steel (MS) is one amongst the most challenging problems faced in various chemical industries. The present work focuses on the potential activity of a naphthalimide derivative namely 2-(2-hydroxyethyl)benzo[de]isoquinoline-1,3-dione (HBIQ) as corrosion inhibitor for MS in sulfamic acid (SA) medium in the temperature range from 303 to 323 K. Potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) were employed in the experimental measurement and HBIQ exhibited 89% inhibition at its optimum concentration. HBIQ demonstrated electrostatic interactions with MS surface and behaved as a mixed type of inhibitor by obeying Langmuir’s isotherm model. Surface characterization of uninhibited and inhibited MS specimens combined with elemental analysis data provided clear evidences for the formation of a protective adsorption layer of HBIQ on MS surface. Spectral analysis such as Ultraviolet visible and Fourier Transform Infra-red spectral analyses were carried out in order to confirm the adsorption of HBIQ on to the metal surface. The density functional theory calculations supported the experimental results and indicated the contribution of delocalized π-electrons in the naphthalimide unit and the lone-pair electrons of oxygen in the carbonyl and hydroxyl group for improved adsorption of HBIQ onto MS surface, thereby reducing the corrosion of the alloy in SA environment.

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