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Development of non-toxic and sustainable corrosion inhibitors is greatly needed, in view of these several forms of green corrosion inhibitors natural Chitosan oligosaccharide gained substantial advancement. In this book chapter, the Chitosan oligosaccharide was modified with an 8-hydroxyquinoline derivative to develop a novel bio-based, green, and sustainable mild steel corrosion inhibitor. Fourier transform infrared spectroscopy and nuclear magnetic resonance were used to characterize the modified oligosaccharide. Electrochemical measurements as well as theoretical investigations have been used to examine the anti-corrosion ability of developed chitosan. Electrochemical results confirm that the modified Chitosan oligosaccharide is a mixed type of inhibitor for mild steel. The experimental results have been in agreement with the theoretical study, which has shown that the developed material exhibits the excellent anti-corrosive activity for mild steel in Hydrochloric acid.

Mild steel is a well-known and widely used material in various industries. However, its exposure to aggressive environments limits its use because of its tendency to corrode. This work focuses on the inhibition of corrosion of mild steel by two organic compounds based on Imidazole, namely 2-(4-chlorophenyl)-1,4,5-triphenyl-1H-imidazole and 1,2,4,5-tetraphenyl-1H-imidazole, in mixed pickling bath. The experimental investigation was carried out using several techniques including electrochemical impedance spectroscopy and potentiodynamic polarization. The adsorption process of corrosion inhibitors on the mild steel surface follows Langmuir adsorption model. Surface characterization analysis using scanning electron microscopy coupled with energy dispersive X-ray analysis (EDX), X-ray diffraction analysis (XRD) supported the formation of a barrier layer that covers the mild steel surface. Weight loss measurements were also tested using UV-vis spectrometry (UV-vis).

In this chapter, the authors investigate recent advancements in the manufacture of chemical compounds containing a benzoxazepine-based heterocycle. Specifically, they synthesized the Benzoxazepine Derivatives using two organic reactions to test its efficacy as an inhibitor against the corrosion of mild steel in acidic pickling baths. The findings reveal that the corrosion inhibitor efficiency increased from 79.4% to 93.3%. This study also employed the Langmuir adsorption model to show that Benzoxazepine Derivatives studied adsorbed spontaneously on the metal surface with a mixed-type nature, forming a coating that is verified by SEM/EDS. The negative free energy of adsorption values and the significant relationship between the inhibitor molecule and the adsorption energy further support our findings. This study demonstrates the potential of benzoxazepine derivatives as effective inhibitors of mild steel corrosion in acidic pickling baths, with significant implications for the manufacturing industry. Continued research in this field is of utmost importance.

Metallic materials are well known and widely used in various industrial sectors. However, they can be easily corroded in various aggressive environments. The protective action of stainless steel by two organic pyrazole compounds: {1-amino-5,10-dioxo-3-(p-tolyl)-5,10-dihydro-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile} and {1-amino-3-(2-chlorophenyl)-5,10-dioxo-5,10-dihydro-1H-pyrazolo[1,2-b] phthalazine-2-carbonitrile} in H2SO4 2.0M medium was studied using the electrochemical technics (Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization), Scanning Electron Microscopy (SEM) and Energy Dispersion X-ray spectroscopy (EDX). Polarization curves indicate that both compounds act as anodic inhibitors. A suitable equivalent electrical circuit model was used to calculate the impedance parameters. The adsorption study showed that these compounds are adsorbed to the steel surface according to the adsorption isotherm of Langmuir. Effect of temperature was also investigated and activation parameters were evaluated.

The aim of this study is the valorization of the Cistus monspeliensis plant, native to North of Morocco, as antioxidant and corrosion inhibitor. Firstly, the plant is extracted by maceration in a mixture of water/acetone solvents. Phytochemical tests are carried out on the extract obtained. The antioxidant power of Cistus monspeliensis extract is evaluated by two methods: the test of reduction of the free radical DPPH∙ (1,1-diphenyl-2-picryl hydrazyl) and that of Ferric reducing antioxidant power (FRAP). The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization are used to study the anticorrosion effect of Cistus monspeliensis extract. The results showed that the extract, 27.6% yield, contains phenolic compounds in the form of flavonoids, hydrolysable and condensed tannins, saponins, reducing sugars and glycosides. This extract has an antioxidant capacity similar to that of ascorbic acid with an inhibition concentration of 0.077 mg/mL 0.102 mg/mL for DPPH and FRAP test, respectively. Tafel plots show that the extract is an excellent cathodic inhibitor. The maximum inhibition efficiency of 92 % was obtained with 0.25 g/L of the inhibitor at 298 k. The impedance plot is characterized by a single capacitive loop attributed to the charge transfer process. The results also showed that the inhibitor acts on the surface of the metal principally by adsorption, leading to the formation of a protective film limiting the corrosion of ordinary steel.

To minimize the metal corrosion, a new glass system titano-zinc phosphate glasses have been synthesized the electrochemical and theoretical investigations were used to study their anticorrosive performance for the carbon steel in 3% NaCl medium. This inhibitor act as great inhibitor for carbon steel in 3% NaCl. In the other hand, the surface of the steel has been analyzed by the scanning electron microscopy SEM. In addition the inhibition efficiency was found to increase with the increase of the inhibitors concentration due to the formation of protective the film on the substrate surface.

In this work, we are interested in studying the effect of the addition three heterocyclic organic compound derived from quinolin-8-ol namely 5-((2, 2, 4, 7-tetramethyl-2, 3-dihydro-1H-benzo[b][1,4]diazepin-1-yl)methyl)quinolin-8-ol(Qn-1), 5-((2, 2, 4-trimethyl-2, 3-dihydro-1H-benzo[b][1, 4] diazepin-1-yl)methyl)quinolin-8-ol (Qn-2) and 5-((2,2,4-trimethyl-7-nitro-2,3-dihydro-1H-benzo[b][1,4]diazepin-1-yl)methyl)quinolin-8-ol (Qn-3) on inhibition of the corrosion of mild steel in acidic medium 2.0 M H3PO4. This study was performed using the electrochemical method (polarization curves and electrochemical impedance spectroscopy). Qn-1, Qn-2 and Qn-3 act as excellent inhibitors for mild steel in 2.0 M H3PO4. In addition, the surface of the mild steel has been analyzed by the SEM-EDX., Moroccan Journal of Chemistry, Vol. 9, No 4 (2021): in progress

The effects of introducing small amounts of phosphorus (P) into α-brass on its corrosion behavior in Azrou soil were examined. Three α-brasses (denoted EM1, EM2, and EM3) with different P contents were studied in this work. These brasses were investigated using Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization (PDP) plots and Scanning Electron Microscopy (SEM), whereas the chemical composition was determined by energy-dispersive X-ray spectroscopy (EDS). The experimental results showed that the most resistant of the three α-brasses to corrosion in this soil was EM3. Moreover, the presence of P in the α-brasses decreased their corrosion rates and increased their corrosion resistance, i.e., the polarization resistance of the brasses to corrosion increased with the P content of the brass. The maximum polarization resistance, Rp = 851 kΩ cm2, occurred with a P content of 0.137%. The observed changes in surface morphology with increasing P content and the corrosion products deposited on the brass surface were examined by X-ray diffraction. EM3 coupons in the studied soil only showed base metal peaks, demonstrating that EM3 is highly resistant to corrosion.

The corrosion inhibition of mild steel in hydrochloric, sulfuric, and phosphoric acids solutions containing a mineral compound-based phosphate (apatite) was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy. Potentio-dynamic polarization measurements reveal that the inhibition efficiency increased with the concentration of the apatite, which appears to be a cathodic type inhibitor in the three mediums. Electrochemical impedance spectroscopy confirms this result; indeed, the transfer resistance increases with apatite concentration. The authors note that the double layer capacitance decreases simultaneously suggesting the formation of an adsorbed layer on the mild steel surface. The inhibition mechanism has been elucidated by a thermodynamic study, which showed that the film was formed by physi-sorption. The adsorption model obeys to the Langmuir adsorption isotherm. The parameters of activation energy were evaluated and discussed.

Purpose The purpose of this paper is to study the effect of silicon and phosphorus content in steel suitable for galvanizing on its corrosion and inhibitor adsorption processes in steels/cetyltrimethylammonium bromide combined and KI (mixture)/5.0 M hydrochloric acid systems has been studied in relation to the temperature using chemical (weight loss), Tafel polarization, electrochemical impedance spectroscopy (EIS), scanning electronic microscope (SEM) analysis and Optical 3D profilometry characterization. All the methods used are in reasonable agreement. The kinetic and thermodynamic parameters for each steels corrosion and inhibitor adsorption, respectively, were determined and discussed. Results show that the adsorption capacity for Steel Classes A and B are better than Steel Class C surfaces depending on their silicon and phosphorus content. Surface analyses via SEM and Optical 3D profilometry was used to investigate the morphology of the steels before and after immersion in 5.0 M HCl solution containing mixture. Surface analysis revealed improvement of corrosion resistance of Steels Classes A and B in the presence of mixture more than Classes C. It has been determined that the adsorbed protective film on the steels surface heterogeneity markedly depends on steels compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content. Design/methodology/approach The effect of silicon and phosphorus content in Steels Classes A, B and C on its corrosion and inhibitor mixture adsorption processes in 5.0 M HCl solution has been studied by weight loss, potentiodynamic polarization, EIS and surface analysis. Findings The inhibition efficiency of mixture follows the order: (Steel Class A) > (Steel Class B) > Steel Class C) and depends on their compositions in the absence of mixture according on their silicon and phosphorus content, that is, the corrosion rate increases with increasing of the silicon and phosphorus content. A potentiodynamic polarization measurement indicates that the mixture acts as mixed-type inhibitor without changing the mechanism of corrosion process for the three classes of mild steels. Originality/value Corrosion rate mild steels in 5.0 M HCl depends on their compositions in the absence of mixture according to their silicon and phosphorus content, that is, the corrosion rate increases with increasing silicon and phosphorus content. The adsorbed protective film on the steels surface heterogeneity markedly depends on steels class’s compositions, that is, the heterogeneity increases with decreasing silicon and phosphorus content.

The present paper examines the adsorption of two novel heterocyclic compounds of the pyran derivatives, namely, 2-amino-4-(2-chlorophenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (PY-2Cl) and 2-amino-4-(4-chlorophenyl)-5-oxo-4,5-dihydropyrano[3,2c]chromene-3-carbonitrile (PY-4Cl) against the corrosion of mild steel (MS) in molar hydrochloric acid (HCl) medium. The experimental investigation was carried out utilizing a series of techniques including Weight Loss (WL), Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP). Results showed that inhibition effectiveness of PY-2Cl and PY-4Cl increases with their concentration. Polarization results showed that PY-2Cl and PY-4Cl displayed mixed type behaviour. Inhibition efficiencies of PY-2Cl and PY-4Cl followed the order: 85.8% (PY-4Cl)

The present investigation focused on the corrosion inhibition of mild steel in 1.0 M HCl medium by new naphthol based on 8-hydroxyquinoline. These products were characterized by 1H-NMRand 13C NMR spectroscopy. The influence of concentration (C) and temperature (T) on the corrosion process of mild steel before and after addition of naphthol derivatives in corrosive solutions has been investigated through weight loss (WL), electrochemical measurements :electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). PDP findings revealed that the used naphthol derivatives exhibit a mixed character. Inhibition efficiencies of Q-1 and Q-2 followed the order: 87.6% (Q-1)

In this work, a new generation of corrosion inhibitors composed of xMCl2-yNa4P2O7 (MCl2 = 2,2’-dibenzimidazolyl butane dichlorhydrates) hybrids materials have been synthesized successfully with five molar ratios (R1, R2, R3, R4, and R5) by soft chemistry route and characterized. The synthesis was performed in aqueous solutions by the ionic exchange between the pyrophosphate anions and the 2,2′-dibenzimidazolyl butane dichlorhydrates cations. The structure and morphology of the synthesized hybrids are studied by infrared spectroscopy (FT-IR), UV–Visible analysis (UV-vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The infrared results show the formation of a new band N-O-P confirming the hybrid structure. The crystalline structure was improved after adding pyrophosphate, confirming the phosphate nucleation and a better settlement of the crystals. These crystals were clearly shown in the SEM images. The corrosion inhibition performance of the prepared compounds were studied on mild steel in 0.5 M sulfuric acid by electrochemical impedance spectroscopy (EIS) and polarization studies. The inhibition efficiency increased with increasing inhibitor concentration, while the corrosion current density decreased. Indeed, the best inhibitor of these hybrids is R1 with an inhibition power of 97.1 % at 300 ppm. The effect of temperature on inhibitory efficiency in a range of 298 to 328K is discussed. The SEM images are also confirmed that the R1 retards the corrosion on the mild steel surface. The EDX analysis presented that this surface is mainly composed of N and P elements. The theoretical calculation results show that the benzimidazole cycle and the heteroatoms of N, O and P are the active sites of inhibitor R1.

Nowadays, the use of green sources for developing the metal corrosion inhibitors attracts a serious interest in many industrial applications. In the present work, the 8-hydroxyquinoline-grafted-Alginate (HQ-g-Alg) is developed as biobased corrosion inhibitor of the mild steel in 1 M HCl solution. The structure of the modified alginate is confirmed using FT-IR, 1H and 13C NMR spectral data. Then, the electrochemical, surface morphology, density functional theory (DFT) and molecular dynamic simulation (MDS) methods were performed to investigate the effects of modified alginate on the mild steel corrosion properties. The study was done at different concentration for HQ-g-Alg and at optimal concentration for Alg. The results show that the modified alginate act as a mixed type inhibitor. The impedance studies showed a rise in the polarization resistance with increasing concentration of the inhibitors. For all studied temperatures, the inhibition efficiency of the modified alginate is more advantageous than the unmodified analogue, reflecting the synergic effects of the molecule (QM) grafted on the biopolymer chains on the meld steel protection in acidic medium. MDS and quantum chemical parameters substantiated with the experimental facts and give further insight information about the inhibition mechanism. Thereby, the present study shows the successful effects of a simple/green chemical modification on the biopolymer efficiency as corrosion inhibitor.

New compounds derived from quinazolinone namely, 3-methyl-2-(p-tolyl) quinazolin-4(3H)-one (QZ-CH3), 2-(4-hydroxyphenyl)-3-methylquinazolin-4(3H)-one (QZ-OH), 3-methyl-2-(4-nitrophenyl) quinazolin-4(3H)-one (QZ-NO2) and 3-methyl-2-phenylquinazolin-4(3H)-one (QZ-H) were synthesized and characterized by RMN spectroscopy. Their inhibition efficiencies against mild steel corrosion in 1.0 M HCl at 298 K were investigated by using electrochemical methods, surface analysis and UV–visible spectrometry coupled with DFT calculations and Monte Carlo (MC) simulation. It is seen that these four products are good corrosion inhibitors for mild steel in 1.0 M HCl, where their inhibition efficiencies increase with concentration to reach maximum values of 92%, 96%, 82%, and 81% at 10−3 M of QZ-OH, QZ-CH3, QZ-NO2 and QZ-H, respectively. In addition, the influence of the temperature solution ranges from 298 K to 328 K, on the performance of the quinazolinone derivatives indicated that it decreases with temperature solution. The activation and thermodynamic parameters indicated that these products act via chemical adsorption on the metallic surface. This finding was confirmed by surface analysis and UV–visible spectrometry with the formation of a thick protective layer on mild steel surface and the formation inhibitor-complex in solution, respectively. Indeed, it is found that these quinazolinone derivatives adsorb on mild steel surface according to Langmuir adsorption isotherm. Finally, the DFT and MC simulation studies don't correlate with electrochemical measurements and surface analysis.

The inhibitive performance of two imidazole derivatives, namely, 1,4,5-triphenyl-2-(4-metyoxyphenyl)-1H-imidazole (P1) and 1,4,5-triphenyl-2-(3,4,5-trimetyoxyphenyl)-1H-imidazole (P2) on the corrosion of steel in hydrochloric acid 1.0 M, has been studied by weight-loss measurement, polarization method, and electrochemical impedance spectroscopy (EIS) and theoretical computational chemistry techniques. The value of inhibition efficiency increases as inhibitor concentration becomes high. The Polarization results indicated that these compounds act as anodic inhibitors in HCl solution. P1 and P2 showed the best protection performances for mild steel in the studied medium. Quantum chemical calculations also showed that imidazole ring has the tendency of interacting with metallic atoms via both forward and backward donations.