The impact of environmentally friendly supramolecular coordination polymers as carbon steel corrosion inhibitors in HCl solution: synthesis and characterization.

Two 3D-supramolecular coordination polymers (SCP1 & SCP2) have been synthesized and characterized by physicochemical and spectroscopic methods. In a solution of 1.0 M HCl, SCPs were used to prevent corrosion of carbon steel (CS). The inhibition productivity (%η) rises as the synthetic inhibitor dose rises, and the opposite is true as the temperature rises. The study was carried out using chemical (mass loss, ML) and electrochemical ( potentiodynamic polarization, PDP and electrochemical impedance microscopy, EIS) techniques, which showed %η reached to 93.1% and 92.5% for SCP1 & SCP2, respectively at 21 × 10-6 M, 25 °C. For the polarization results, SCPs behave as mixed-type inhibitors. With increasing doses of SCPs, the charge transfer resistance grew and the double layer's capacitance lowered. The creation of a monolayer on the surface of CS was demonstrated by the finding that the adsorption of SCPs on its surface followed the Henry adsorption isotherm. The parameters of thermodynamics were computed and explained. The physical adsorption of SCPs on the surface of CS is shown by the lowering values of free energy (∆Goads < - 20 kJ mol-1) and increasing the activation energy (E*a) values in presence of SCP1 & SCP2 than in their absence. Atomic force microscope (AFM) and scanning electron microscopy (SEM) demonstrated the development of a protective thin film of SCPs precipitated on the surface of CS. There is a strong matching between results obtained from experimental and theoretical studies. Results from each approach that was used were consistent.

Insights into the use of two novel supramolecular compounds as corrosion inhibitors for stainless steel in a chloride environment: experimental as well as theoretical investigation.

Novel supramolecular (SCPs) compounds such as: {[Ni (EIN)4(NCS)2]}, SCP1 and {[Co (EIN)4 (NCS)2]}, SCP2 have been studied using weight loss (WL) and electrochemical tests on the corrosion performance of stainless steel 304 (SS304) in 1.0 M hydrochloric acid (HCl) solution. The experimental results revealed that inhibition efficacy (η%) rises with increasing concentrations of SCPs and reached 92.3% and 89.6% at 16 × 10-6 M, 25 °C, from the WL method for SCP1 and SCP2, respectively. However, by raising the temperature, η% was reduced. Polarization measurements (PDP) showed that the SCPs molecules represent a mixed-type. The SCPs were adsorbed on a SS304 surface physically, and the Langmuir adsorption isotherm was found to govern the adsorption process. The determination of thermodynamic parameters was carried out at various temperatures. Quantum chemical calculations were calculated to prove the adsorption process of SCP components, using the molecular dynamics (MD) simulations and electron density map. The inhibition performance of SCPs for SS304 dissolution in an acidic medium was proved to be excellent through FT-IR and AFM analysis. The results obtained from all measurements exhibit a high level of agreement with each other.

Novel porphyrin derivatives as corrosion inhibitors for stainless steel 304 in acidic environment: synthesis, electrochemical and quantum calculation studies.

A Novel 5,10,15,20-tetra (thiophen-2-yl) porphyrin (P1) and 5,10,15,20-tetrakis (5-Bromothiophen-2-yl) porphyrin (P2) were successfully synthesized, and their chemical structures were proved based on its correct elemental analysis and spectral data (IR and 1H-NMR). These compounds were examined as corrosion inhibitors for stainless steel 304 (SS304) in 2 M HCl utilizing mass reduction (MR) and electrochemical tests at inhibitor concentration (1 × 10-6-21 × 10-6 M). The protection efficiency (IE %) was effectively enhanced with improving the concentration of investigated compounds and reached 92.5%, 88.5% at 21 × 10-6 M for P1 & P2, respectively and decreases with raising the temperature. Langmuir's isotherm was constrained as the best fitted isotherm depicts the physical-chemical adsorption capabilities of P1 & P2 on SS304 surface with change in ΔGoads = 22.5 kJ mol-1. According to the PDP data reported, P1 and P2 work as mixed find inhibitors to suppress both cathodic and anodic processes. Porphyrin derivatives (P1 & P2) are included on the surface of SS304, according to surface morphology techniques SEM/EDX and AFM. Quantum calculations (DFT) and Monte Carlo simulation (MC) showed the impact of the chemical structure of porphyrin derivatives on their IE %.

Nano-metal-organic frameworks as corrosion inhibitors for strengthening anti-corrosion behavior of carbon steel in a sulfuric acid environment: from synthesis to applications.

In order to demonstrate the effect of Nano-metal organic frameworks, [Cu2(CN)4(Ph3Sn) (Pyz2-caH)2] (NMOF1) and [∞3[Cu(CN)2(Me3Sn)(Pyz)]] (NMOF2) as corrosion inhibitors for C-steel in 0.5 M sulfuric acid solutions, the following methods were utilized: mass reduction (MR), potentiodynamic polarization (PDP), and AC electrochemical impedance (EIS). The results of the experiments showed that by increasing the dose of these compounds, the inhibition efficacy (η%) of C-steel corrosion increased and reached 74.4-90% for NMOF2 and NMOF1 at a dose of 25 × 10-6 M, respectively. On the other hand, the η% decreased as the temperature range rose. Parameters for activation and adsorption were determined and discussed. Both NMOF2 and NMOF1 were physically adsorbed on the surface of C-steel and conformed to the Langmuir adsorption isotherm model. The PDP studies revealed that these compounds functioned as mixed type inhibitors, i.e. affecting both metal dissolution and hydrogen evolution reactions. Attenuated Total Reflection Infra-Red (ATR-IR) analysis was carried out to determine the morphology of the inhibited C-steel surface. There is good agreement between the findings of EIS, PDP and MR.

Experimental and computational chemical studies on the corrosion inhibition of new pyrimidinone derivatives for copper in nitric acid.

Inhibition of copper corrosion by some pyrimidinone derivatives, namely; (E)-N-(3-((1,3-dimethyl-2,4,6-trioxohexahydropyrimidin-5-yl)diazenyl)-2,5-diethoxyphenyl)benzamide (MA-975) and(E)-6-(4-((4-chlorophenyl)diazenyl)-3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)-1,3 dimethylpyrimidine-2,4(1H,3H)-dione (MA-978C) in 1.0 M nitric acid (HNO3) was studied using weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) measurements. The efficiency of inhibition increases as the concentration of inhibitor increases, and it also increases as the temperature increases. With the addition of the examined inhibitors, significant corrosion protection was obtained, and (MA-975) showed a very promising % IE (89.59%) at 21 × 10-6 M using the (WL) method. The polarization data revealed that these compounds act as mixed-type compounds and are adsorbed on the copper surface following Langmuir adsorption isotherm forming a protective thin film protecting the metal in the corrosive media. Scanning electron microscopy (SEM) and Energy Dispersive X-ray were used to examine the surface morphology of copper samples. Quantum calculations and Monte Carlo simulation techniques were applied with informative yields and the results matched the experimental findings.