Synthesis, characterization and electrochemical analysis of cysteine modified polymers for corrosion inhibition of mild steel in aqueous 1 M HCl

Unraveling the Adsorption Mechanism and Anti-Corrosion Functionality of Dextrin and Inulin as Eco-Friendly Biopolymers for the Corrosion of Reinforced Steel in 1.0 M HCl: A Thermodynamic and Kinetic Approach

Reinforcing steel (RS) is mainly used in building construction and many industries, but it suffers from corrosion problems, especially in acidic environments. Biopolymers are characterized by their unique chemical composition, as they contain a variety of functional groups that are capable of binding strongly to the metal surface and forming a protective layer on it. Herewith, two biopolymers, viz. dextrin (Dex) and inulin (Inu), were tested as eco-friendly inhibitors for the corrosion of RS in 1.0 M HCl medium at different temperatures. Various experimental tools were utilized in this research. The inhibition efficiencies (% IEs) of the tested polymeric compounds were improved by increasing their doses while reducing with rising temperature. The % IEs of Dex and Inu at a dose of 500 mg/L reached 85% and 93%, respectively. The examined biopolymers displayed cathodic/anodic behavior (mixed type) with a foremost anodic one. The acquired higher % IEs were demonstrated by intense adsorption of Dex and Inu on the RS surface fitting the Langmuir isotherm. The influence of rising temperature in the range of 288-318 K on the corrosion behavior was examined, and the evaluated thermodynamic and kinetic parameters sustained the mechanism of physical adsorption of the polymeric inhibitors. Additionally, the kinetics of corrosion, as well as its inhibition by Dex and Inu, were also investigated. The SEM micrographs of the RS surfaces were accorded with all utilized experimental tools. The results gained from all used tools were discovered to be in good agreement with each other.

Anticorrosion Evaluation of Novel Water-Soluble Schiff Base Molecules for C1018 Steel in CO2-Saturated Brine by Computational and Experimental Methodologies

In this work, three different derivatives of Schiff base, as mono- and di-Schiff bases, were successfully synthesized by the facile condensation of 2-aminopyridine, o-phenylenediamine, or 4-chloro-o-phenylenediamine with sodium salicylaldehyde-5-sulfonate (H1, H2, and H3, respectively). A combination of theoretical and practical studies was accomplished on the corrosion mitigation effect of the prepared Schiff base derivatives on C1018 steel in CO₂-saturated 3.5% NaCl solution. The corrosion inhibition effect of the synthesized Schiff base molecules was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. The outcomes exhibited that Schiff base derivatives have an outstanding corrosion inhibition effect on carbon steel at particularly low concentrations in sweet conditions. The outcomes showed that Schiff base derivatives exhibited a satisfactory inhibition efficiency of 96.5% (H1), 97.7% (H2), and 98.1% (H3) with a dosage of 0.5 mM at 323 K. SEM/EDX analysis confirms the adsorbed inhibitor film's formation on the metal surface. The polarization plots indicate that the studied compounds behaved as inhibitors of the mixed type according to the isotherm model of Langmuir. The computational inspections (MD simulations and DFT calculations) display a good correlation with the investigational findings. The outcomes could be applied to assess the efficiency of the inhibiting agents in the gas and oil industry.

Stimuli-Responsive Macromolecular Architecture by Butler Cyclopolymerizations: Synthesis and Applications

This article reviews the synthesis of polyzwitterions (PZs) (poly-carboxybetaines, -phosphonobetaines, and -sulfobetaines) having multiple pH-responsive centers. The synthesis follows the Butler cyclopolymerization protocol involving a multitude of diallylammonium salts and their copolymerization with SO₂ and maleic acid. The PZs have been transformed into cationic-, anionic-polyelectrolytes, and polyampholytes under the influence of pH. Particular attention is given to the application of these polymers as antiscalants, mild steel corrosion inhibitors, components in constructing Aqueous Two-Phase Systems (ATPSs), and membrane modifiers. The ATPSs could be used to separate various biomolecules, including proteins. Many amphiphilic polymers incorporating a few mol % hydrophobic monomers have shown enhanced viscosities and could be suitable for applications in oil fields. The progress of applying Butler cyclopolymerization in reversible addition-fragmentation chain transfer (RAFT) chemistry has been discussed. Future works are expected to focus on RAFT cyclopolymerization to construct block copolymers.

Corrosion mitigation performance of disodium EDTA functionalized chitosan biomacromolecule - Experimental and theoretical approach

Disodium ethylenediaminetetraacetate salt is known for its excellent coordinating properties with the metal ions. The present study deals with the investigation of the prepared Disodium EDTA functionalized chitosan in corrosion inhibition for mild steel in 1 M HCl. The modified chitosan was characterized by spectral studies, thermal analysis, and Zeta potential studies. The corrosion inhibition efficiency (%) was evaluated using the gravimetric method and electrochemical studies. The electrochemical studies included potentiodynamic polarization, linear polarization resistance, and electrochemical impedance methods. The modified chitosan polymer showed an inhibition efficiency of 96.63% for 500 ppm at 303 K. Adsorption process obeyed Langmuir isotherm. Experimental results and theoretical calculations endorsed initial physisorption followed by a chemisorption process. Surface characterization studies supported the formation of a protective film that enabled the inhibition process. Density functional theory, Monte Carlo studies, and molecular dynamics simulation studies show a good agreement with the experimental results. Two-way Analysis of Variance was performed to test the influence of immersion period and inhibitor concentration on the corrosion rate using the statistical software IBM SPSS 20.0. A quartic model was generated as the best fit with the highest R2 value of 0.973. Design Expert software was employed for statistical modeling fit.

Polymers Decorated with Functional Motifs for Mitigation of Steel Corrosion: An Overview

Corrosion is a hazardous phenomenon having a devastating impact on technological and industrial applications, particularly in the oil and gas industries. Therefore, controlling the corrosion of metals is an important activity of technical, economical, environmental, and aesthetical importance in order to save huge expenses in materials, equipment, and structure. The use of corrosion inhibitors is one of the best options for controlling the metallic corrosion in various corrosive media. Numerous problems aroused with the use of inorganic and small molecule organic corrosion inhibitors, and the use of polymeric corrosion inhibitors came into limelight. This review article provides an overview of the recent development of different classes of corrosion inhibitors with special emphasis on different functional motifs of natural, synthetically modified natural, and synthetic polymeric materials. The significance, mechanism, and challenges of using polymeric materials as corrosion inhibitors are also highlighted in the review.

New, Amino Acid Based Zwitterionic Polymers as Promising Corrosion Inhibitors of Mild Steel in 1 M HCl

The zwitterionic monomers, N,N’-diallylamino propanephosphonate and amino acid residual N,N’-diallyl-l-methionine hydrochloride were synthesized, with excellent yields. These monomers were utilized in the preparation of zwitterionic homo and co-cyclopolymers 5–7 in aqueous solution using 2,2′-azobis (2-methylpropionamidine) dihydrochloride as an initiator. The polymers were characterized by FT-IR, NMR, and TGA. The performance of these synthesized polymers on mild steel in acidic solution was investigated by gravimetric method, Tafel extrapolation, linear polarization resistance, and electrochemical impedance spectroscopy. At 313 K, the maximum inhibition efficiencies of corrosion inhibitors 5–7 at 4.50 × 10−4 mol L−1 were found to be 85.2%, 83.3%, and 99.5%, respectively. The inhibition efficiencies obtained from gravimetric weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy measurements were in good agreement. Different adsorption isotherms were also explored to find the best fit, and found to obey Langmuir adsorption isotherm. The thermodynamic parameters, such as activation energy (Ea), standard enthalpy of activation (ΔH*), standard entropy of activation (ΔS*), adsorption–desorption equilibrium constant (Kads), and standard free energy of adsorption (ΔGoads), were determined. Electrochemical data indicated that the zwitterionic copolymer 7 acts as a mixed type inhibitor under the influence of anodic control. The surface morphology of mild steel corrosion was evaluated without and with corrosion inhibitors by AFM, SEM-EDX, and XPS, which confirmed the adsorption of inhibitor molecules on the metal surface.