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Environmental pollution is a current global concern. Cleaning of petroleum pipes involve 15% hydrochloric acid (HCl) treatment. Metal corrosion because of acid treatment is a common problem in petroleum industry. Chemical anticorrosive agent can be used but trigger environmental concerns. Therefore, use of waste material as green anticorrosive agent is a preferable solution to corrosion of petroleum grade steel. In current study waste from Punica granatum fruit peel was used to prevent corrosion of stainless steel 410 (SS 410) in presence of 15% HCl. Potentiodynamic polarization study revealed maximum 91.79 % corrosion inhibition efficiency of Punica granatum fruit peel extract at 4g/L in 15% HCl solution. P. granatum peel extract showed anodic type of inhibition. The adsorption of the peel extract of P. granatum on the steel surface was evident from Scanning electron, atomic force microscopy and X-rays diffraction studies. The P. granatum peel extract formed a monolayer on the surface of SS 410 as it followed Langmuir adsorption isotherm. Theoretical and computational studies confirmed that Quercetin was main phytochemical responsible for the anti-corrosive effect. The interaction between Quercetin and SS 410 surface interactions was studied by Molecular simulation studies. Overall P. granatum peel extract possessed anti-corrosive behaviour against SS 410 surface in 15% hydrochloric acid on.

Plant extracts of different parts such as leaves, stem, bark, peel, flower etc. are widely utilized as environmental friendly corrosion inhibitors at the place of traditional toxic organic corrosion inhibitors. Ideally, use of aqueous extract would be preferred over organic extract as farmer one can be prepared more eco-friendly and economically than latter one. In the present investigation, corrosion inhibition potential, chemical reactivity and adsorption tendency of phytochemicals present in the Calotropis procera flower has been described with the aid of computational analyses. Literature study suggests that various phytochemicals are present in the Calotropis procera plant. Computational studies were performed on this phytochemicals to find out the most effective one. Results suggests that 4′Methyl-2 Phenylindole and 5,12-Naphthacenedione, 8-ethyl serve as the most effective inhibitors and they become effective by adsorbing on the metallic surface using their functional groups and aromatic rings. In other phytochemicals, polar functional groups and π-electrons of multiple bonds orient towards metal surface whereas long hydrophobic chains directed toward the solution side.

Various concentration of Solanum surattense (S. surattense) aerial parts extract was utilized for low carbon steel (LCS) in the presence of corrosive medium (0.5 M sulfuric acid) utilizing weight-loss technique and electrochemical methods (Tafel and EIS). The mixed adsorption status on the LCS was exhibited by potentiodynamic polarization. S. surattense accomplished 93% corrosion inhibition effectiveness at an inhibitor concentration of 500 mg/L. SEM and AFM was utilized to distinguish the thin film framed on the outside of the metal alloy to protect it from corrosion. The molecular adhesion of the inhibitor was demonstrated to be Ultraviolet–visible (UV–Vis) spectroscopic method. The FT-IR strategy supported the existence of different functional groups and different atoms other than Carbon and Nitrogen in the protective extract. Thin layer adhesion of the inhibitor molecules outside of LCS metal substrate obeyed the Langmuir adsorption isotherm and acted as mixed type inhibitor. DFT revealed an entirely important report with high EHOMO and low ELUMO values for active phytoconstituents showing potential nature of inhibitor and good agreements with experimental outcomes. The whole acquired results entail that S. surattense creates protective coat hence limit the degree of LCS degradation.

Various concentrations of Gloriosa superba seeds extract were utilized for low carbon steel (LCS) within the sight of a destructive solution (0.5 M sulfuric corrosive) utilizing electrochemical techniques (Tafel and EIS) followed by weight loss method. The condition of mixed adsorption to LCS is confirmed by potentiodynamic polarization. G. superba demonstrated a corrosion restraint effectiveness of 93.84% at 700 mg/L. SEM and AFM were utilized to recognize the formation of a surrounding protective layer on LCS to shield it from corrosive media. The inhibitor adsorption was shown by noticeable spectroscopic strategies. The FT-IR system affirmed the presence of various utilitarian gatherings and heteroatoms in the inhibitor. Adsorption of inhibitory atoms on the LCS followed the Langmuir adsorption isotherm. Hypothetical exploration has demonstrated a significant relationship. All the outcomes ensure that G. superba makes a defensive layer to reduce the corrosion process.

The anticorrosive effect of an epoxy resin (DGEDDS-MDA) based on diglycidyl ether 4, 4′-dihydroxydiphenylsulfone (DGEDDS) and 4,4′-Methylene dianiline (MDA) with and without titanium dioxide (TiO2) for carbon steel (CS) corrosion in 3% NaCl solution is reported. The composite of DGEDDS-MDA with TiO2 is designated as DGEDDS-MDA-TiO2. Electrochemical and computational techniques were used to demonstrate the anticorrosive effectiveness of the DGEDDS-MDA and its TiO2 composite. The effect of UV irradiation (for 2000 h) on effectiveness of DGEDDS-MDA and its TiO2 composite showed that the presence of the TiO2 appreciably enhanced the corrosion inhibition effect of DGEDDS-MDA. In order to reinforce the experimental findings, reactivity of DGEDDS-MDA with metallic surface was also studied using computational techniques. DFT study revealed that DGEDDS-MDA interacts strongly with metal surface using donor-acceptor mechanism. Polar functional groups (–OH & –N–) and aromatic rings act as adsorption centers. MD simulations study showed that DGEDDS-MDA adsorbs using flat orientation and its orientation is greatly affected by TiO2.

This study reports the evaluation of the anticorrosive performance of two macromolecular aromatic epoxy resins (ERs), namely, tetra glycidyl of ethylene dianiline (TGEDA) and hexaglycidyl Tris (p-ethylene dianiline) phosphoric triamide (HGEDPAT) and their polymer composite reinforced with Zinc for copper corrosion in 3% NaCl using the computational and experimental analyses. Electrochemical results showed that HGEDAPT cured with methylene dianiline (MDA) showed better protection efficiency with optimum corrosion current density (icorr) value of 2.0 μ cm−2 and the polarization resistance (Rp) value of 17.00 kΩ·cm2 than that of TGEDA-MDA having icorr value of 2.4 μ cm−2 and the Rp value of 15.24 kΩ·cm2. The anti-corrosive effect of TGEDA-MDA and HGEDAPT-MDA was evaluated in the presence of 5% zinc (Zn). Experimental results demonstrate that the presence of 5% of zinc in TGEDA-MDA and HGEDAPT-MDA formulations significantly enhanced their protection ability. The anticorrosive effect of the different formulations followed the order: ER1 (TGEDA-MDA) (potentiodynamic polarization (PDP); 90% and electrochemical impedance spectroscopy (EIS) 92%)

Present study deals with the synthesis, characterization and corrosion inhibition effect of a hexafunctional cyclotriphosphazene derivative, namely 2,2,4,4,6,6-hexakis(oxiran-2-ylmethoxy)-1,3,5,2δ,4δ,6δ-triazatriphosphinine(HPGCP)for copper in 3 wt% NaCl medium. The synthesized HPGCP was characterized using numerous spectral techniques such as1H, 13C, 31P NMR (Nuclear magnetic resonance) and Fourier-transform infrared spectroscopy (FT-IR) methods. Anti-corrosive effect of the HPGCP was measured using electrochemical and computational methods. Results showed that HPGCP exhibited highest protection efficiency of 95% at as low as 10−3 M concentration. Polarization studies showed that HPGCP acted as mixed type inhibitor and its adsorption obeyed the Langmuir adsorption isotherm model. Density Functional Theory (DFT) based computational studies demonstrate that HPGCP interacts with copper surface using donor-acceptor interactions in which three nitrogen atoms and six π-electrons of the cyclotriphosphazene ring play significant role in metal-inhibitor interactions. Molecular dynamic (MD) simulations study demonstrated that HPGCP spontaneously interacts with metallic surface using its electron rich centers and acquires the planar orientation. Experimental results were well corroborated with the computational results.

In present study, a tetra-functionalized aromatic epoxy pre-polymer namely, 4,4′-oxybis(N,N-bis(oxiran-2-ylmethyl)aniline) (AA2) was synthesized and established as corrosion inhibitor for carbon steel corrosion in 1 M HCl medium. The prepolymer was characterized by proton nuclear magnetic resonance (1H NMR) and Fourier-transform infrared spectroscopy (FT-IR) spectral techniques and its inhibition property was demonstrated using electrochemical open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), surface scanning electron microscopy (SEM) analysis coupled with energy dispersive spectroscopy (EDS) analysis and computational density functional theory (DFT) and molecular dynamic (MD) simulations methods. Electrochemical studies demonstrate that AA2 acts as sensibly good inhibitor for carbon steel in 1 M HCl medium and showed highest efficiency of as high as 91.3% at 10−3 M. The PDP results show that AA2 behaves as predominantly cathodic type of inhibitor. SEM analysis coupled with EDS showed that AA2 forms surface protective films and isolates the metal from aggressive solution. DFT studies suggest that both neutral as well as cationic forms of the AA2 strongly interact with metallic surface using two aromatic and four oxirane rings. Molecular dynamic simulations (MDS) study showed that AA2 adsorb strongly on metallic surface using their electron rich centers and acquires the parallel or flat orientation. Outcomes of the experimental (SEM-EDS, OCP, EIS and PDP) and computational (DFT and MDS) studies were in excellent concurrence.

Present study deals with the synthesis, characterization and inhibition property of two epoxy resins (ERs) namely,2,2′-(((sulfonylbis(4,1-phenylene)) bis (oxy))bis(methylene)) bis (oxirane) (ER1) and 2,2′-bis(oxiran-2-ylmethoxy)-1,1′-biphenyl (ER2) on carbon steel corrosion in 1 M HCl medium using experimental and computational methods. Results showed that inhibition efficiency of ERs increases on increasing their concentration. ER1 and ER2 showed highest inhibition efficiencies of 98.1% and 95.6%, respectively at 10−3 M concentrations. Results showed that adsorption of ERs on the carbon steel surface obeyed the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) study suggested that ERs protect the metallic superficial through their adsorption and development protective films. Different computational parameters such as ionization potential (I), electron affinity (A), energy band gap (ΔE),electronegativity (χ), dipole moment (μ), hardness (η), softness (σ), electrophilicity and (ω) nucleophilicity (e) were computed for neutral as well as protonated forms of ER1 and ER2. Adsorption behavior and the orientation of ER1 and ER2 on metallic surface were studied by Monte Carlo (MC) simulations. Results derived from different experimental methods were supported by computational studies using DFT and Monte Carlo methods.