Myrtus Communis as Green Inhibitor of Copper Corrosion in Sulfuric Acid

Development of Natural Plant Extracts as Sustainable Inhibitors for Efficient Protection of Mild Steel: Experimental and First-Principles Multi-Level Computational Methods

In the present work, we present the superior corrosion inhibition properties of three plant-based products, Fraxinus excelsior (FEAE), Zingiber zerumbet (ZZAE), and Isatis tinctoria (ITAE), that efficiently inhibit the corrosion of mild steel in phosphoric acid. The anti-corrosion and adsorption characteristics were assessed using a combination of experimental and computational approaches. Weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy methods were used to evaluate the inhibitive performance of the inhibitors on the metal surface. Then, both DFT/DFTB calculations and molecular dynamic simulations were further adopted to investigate the interaction between organic inhibitor molecules and the metal surface. The protective layers assembled using the active constituents, such as carbonyl and hydroxyl groups, of the three plant-based products offer high electrochemical stability at high temperatures and robust protection against aggressive acidic solutions. All electrochemical measurements showed that the inhibition performance of extracts increased by increasing their concentration and improved in the following order: FEAE > ZZAE > ITAE. Further, these extracts worked as mixed-type inhibitors to block the anodic and cathodic active sites on the mild steel surface. Multi-level computational approaches revealed that FEAE is the most adsorbed inhibitor owing to its ability to provide electron lone pairs for electrophilic reactions. The experimental and theoretical results showed good agreement. These results indicate the possibility of replacing conventional compounds with natural substituted organic products in the fabrication of hybrid materials with effective anti-corrosion performance.

Synthesis of tolyl guanidine as copper corrosion inhibitor with a complementary study on electrochemical and in silico evaluation

A rapid and new synthetic route for N,N'-di-o-tolyl guanidine (DTG) synthesis from cheap materials is reported. The performance of DTG as an excellent inhibitor for delaying copper (Cu) corrosion with an efficiency higher than 98% at 20 × 10^-6 M in an acidic solution was investigated via electrochemical measurements. These measurements included PDP, EFM, and EIS spectroscopy. The experimental data indicated that DTG has an efficient inhibiting effect on the corrosion of Cu in acidic media.The DTG was adsorbed on to the Cu surface via chemical adsorption and followed the Langmuir route. The PDP measurements revealed that DTG acted as a mixed inhibitor. Furthermore, EIS data showed that the DTG adsorbed through the metal/electrolyte interface. This resulted in forming a DTG protective layer on the Cu surface, thereby impeding the dissolution of Cu in the acidic solution. The corrosive solution containing the DTG inhibitor after immersion of the Cu specimen for 48 h, which promoted the formation of a complex between the Cu cation and DTG, was investigated via ultraviolet/visible spectroscopy. In addition, the formation of a DTG protective layer on the Cu surface was confirmed via scanning electron microscopy and atomic force microscopy analysis of the Cu surface morphology. Moreover, the active centers for interaction with the Cu surface in an acidic solution were investigated via in silico evaluation of DTG.

A review of plant metabolites with metal interaction capacity: a green approach for industrial applications

Rapid industrial development is responsible for severe problems related to environmental pollution. Many human and industrial activities require different metals and, as a result, great amounts of metals/heavy metals are discharged into the water and soil making them dangerous for both human and ecosystems and this is being aggravated by intensive demand and utilization. In addition, compounds with metal binding capacities are needed to be used for several purposes including in activities related to the removal and/or recovery of metals from effluents and soils, as metals' corrosion inhibitors, in the synthesis of metallic nanoparticles and as metal related pharmaceuticals, preferably a with minimum risks associated to the environment. Plants are able to synthesize an uncountable number of compounds with numerous functions, including compounds with metal binding capabilities. In fact, some of the plants' secondary metabolites can bind to various metals through different mechanisms, as such they are excellent sources of such compounds due to their high availability and vast diversity. In addition, the use of plant-based compounds is desirable from an environmental and economical point of view, thus being potential candidates for utilization in different industrial activities, replacing conventional physiochemical methods. This review focuses on the ability of some classes of compounds that can be found in relatively high concentrations in plants, having good metal binding capacities and thus with potential utilization in metal based industrial activities and that can be involved in the progressive development of new environmentally friendly strategies.

Surface analysis of 4-(bis(5-bromo-1H-indol-3-yl)methyl)phenol adsorbed on copper by spectroscopic experiments

The new compound of 4-(bis(5-bromo-1H-indol-3-yl)methyl)phenol (BMP) is synthesized through a one-step reaction. Then the inhibition mechanism of inhibitor on copper surface is investigated by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Moreover, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) is employed to characterize the surface morphology of studied copper and electrochemical impendence spectroscopy (EIS) is carried out to study the inhibition efficiency of the inhibitor. From these results obtained, it can be concluded that BMP is considered as corrosion inhibitor for copper in sulfuric solution.

Experimental and DFT studies on the ultrasonic energy-assisted extraction of the phytochemicals of Catharanthus roseus as green corrosion inhibitors for mild steel in NaCl medium

Catharanthus roseus (Apocynaceae family) extract is rich in organic phytochemicals such as alkaloids, polyphenolic compounds, and flavonoids. It contains several functional entities such as fused heterocycles, and hydroxyl and carbonyl groups, which could be useful for corrosion inhibition of mild steel in NaCl environments. In the present work, ultrasonic energy was used to obtain the ethanolic extracts of root and stem which were then tested as corrosion inhibitors for mild steel in the presence of 3.5% NaCl. The corrosion inhibition process was studied by UV-visible spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, weight loss, and electrochemical methods. After immersing in the corrosive medium, the microstructures of mild steel were investigated by scanning electron microscopy, X-ray diffraction, and ellipsometry. The extract of C. roseus showed excellent adsorption on mild steel surface as confirmed by DFT calculations. The results indicate that the extract of C. roseus acts as a mixed type corrosion inhibitor, where the stem extract is the most efficient inhibitor in 3.5% NaCl solution possibly due to the higher active area of stem phytochemicals.

C. roseus phytochemicals are physisorbed on the 111 Fe surface, and the oxygen non-bonding electron chemisorbed on the polarized state 111 Fe surface.

Nano- to Micro-Self-Aggregates of New Bisimidazole-Based Copoly(ionic liquid)s for Protecting Copper in Aqueous Sulfuric Acid Solution

This study presents the synthesis of two new bisimidazole-based copoly(ionic liquid)s (PILs) through multistep preparation routes. It is shown that the target PILs can display orderly molecular stacking, and nano- to micro-self-aggregates are yielded in aqueous sulfuric acid solution, which are characterized by various technologies including scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. The studied PIL aggregates show strong chemical adsorption onto the copper surfaces demonstrated by Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the anticorrosion performance of the studied PIL aggregates is shown using polarization curves and impedance spectroscopy. As a result, the target PIL aggregates show great corrosion inhibition performance to protect copper in aggressive acid medium.

Corrosion inhibition of mild steel in sulfuric acid solution by loquat (Eriobotrya japonica Lindl.) leaves extract

The inhibition performance and mechanism of loquat leaves extract (LLE) for the corrosion of mild steel in 0.5 M H2SO4 were investigated using weight loss method, electrochemical measurements and scanning electron microscope (SEM). The results revealed that LLE acted as a modest cathodic inhibitor, its inhibition efficiency increased with the concentration of LLE and reached a maximum value of 96% at the 100% V/V concentration, but decreased with incremental temperature. Besides, it was found that the adsorption of LLE on steel surface obeyed Langmuir adsorption isotherm, and then the thermodynamic and kinetic parameters were further determined accordingly. Furthermore, LLE was preliminarily separated by pH-gradient sedimentation and the synergistic inhibition between the isolates was investigated.

Halogeno-substituted indazoles against copper corrosion in industrial pickling process: a combined electrochemical, morphological and theoretical approach

The inhibitive properties of four indazole-based compounds (IA, 4-FIA, 4-CIA, and 4-BIA) on copper corrosion in 0.5 M H₂SO₄ solution were investigated using electrochemical measurements, surface characterization techniques and molecular modelling methods. Electrochemical tests indicate that the inhibition efficiencies increase with incremental concentration and all halogeno-substituted indazoles (HIAs) possess superior inhibitive ability to native IA. The specific rating of inhibition performance obeys the order: IA < 4-FIA < 4-BIA < 4-CIA. All inhibition efficiencies of HIAs obtained were over 96% in 1 mM, especially, 4-CIA reaches 99.6%. Moreover, the corresponding inhibition mechanism was elucidated via quantum chemical calculations allied to molecular dynamics simulation. In summary, the present study can help us to gain insight into the effect of halogeno-substitution on the inhibition efficiency of the IA molecule.

The inhibitive properties of four indazole-based compounds on copper corrosion in 0.5 M H₂SO₄ solution were investigated using electrochemical measurements and molecular modelling methods.

Functional Multi-Nanolayer Coatings of Amorphous Carbon/Tungsten Carbide with Exceptional Mechanical Durability and Corrosion Resistance

A novel functional multilayer coating with periodically stacked nanolayers of amorphous carbon (a:C)/tungsten carbide (WC) and an adhesion layer of chromium (Cr) was deposited on 304 stainless steel using a dual magnetron sputtering technique. Through process optimization, highly densified coatings with high elasticity and shear modulus, excellent wear resistance, and minimal susceptibility to corrosive and caustic media could be acquired. The structural and mechanical properties of the optimized coatings were studied in detail using a variety of analytical techniques. Furthermore, finite element method simulations indicated that the stress generated due to contact against a steel ball was distributed well within the coating, which allowed the stresses to be lower than the yield threshold of the coating. Thus, an ultralow wear rate of ∼10^-12mm³/N mm could be achieved in dry sliding conditions under relatively high Hertzian contact pressures of ∼0.4-0.9 GPa. The amorphous and pinhole-free structure of the individual layers, sufficient number of pairs, and the relatively dense stacked layers resulted in significant polarization resistance (Z″ = 5.5 × 10⁶ Ω cm²) and increased the corrosion resistance of the coating by 10-fold compared to that of recently reported corrosion-resistant coatings.

Experimental and theoretical studies on the corrosion inhibition of copper by two indazole derivatives in 3.0% NaCl solution

Corrosion experiments and theoretical calculations were performed to investigate the inhibition mechanism of indazole (IA) and 5-aminoindazole (AIA) for copper in NaCl solution. The results obtained from weight loss and electrochemical experiments are in good agreement, and reveal that these compounds are high-efficiency inhibitors with inhibition efficiency order: AIA>IA, which was further confirmed by field emission scanning electronic microscope (FESEM) observation. Besides, the quantum chemical calculations and molecular dynamics (MD) simulation showed that both studied inhibitors are adsorbed strongly on the copper surface in parallel mode. The adsorption of these molecules on copper substrate was found to obey Langmuir isotherm.

Strychnos nuxvomica, Piper longum and Mucuna pruriens seed extracts as eco-friendly corrosion inhibitors for copper in nitric acid

The inhibitive effect of the Strychnos nuxvomica (SN), Piper longum (PL) and Mucuna pruriens (MP) seeds extract on the corrosion of copper in 3 M HNO₃ solution was studied using gravimetric and electrochemical techniques.