Chitosan Schiff base as eco-friendly inhibitor for mild steel corrosion in 1 M HCl

In the present study, natural biopolymer chitosan was modified into its Schiff base derivative with salicylaldehyde by condensation method. The prepared chitosan salicylaldehyde Schiff base was characterized using ultraviolet spectroscopy, fourier transform infrared spectroscopy, scanning electron microscope and elemental analysis. Thermal analysis was also carried out to determine the thermal stability of the derivative. To explore the corrosion inhibition performance of the chitosan Schiff base, weight loss, and electrochemical techniques were conducted. The inhibitor reduces the metallic corrosion by adsorbing on to the metal surface. The adsorption of chitosan Schiff base on mild steel surface in 1 M HCl follows Temkin isotherm model. Thermodynamic parameters of adsorption and corrosion process were calculated, which revealed the chemical nature of adsorption. SEM and energy dispersive X-ray spectroscopic analysis confirmed the formation of protective chitosan derivative layer on the mild steel surface.     

Empirical and theoretical investigations on the corrosion inhibition characteristics of mild steel by three new Schiff base derivatives

Synthesis, adsorption and corrosion inhibiting effect of three new Schiff base compounds on mild steel in 1.0?M HCl were explored using weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. The empirical results showed that three Schiff base compounds inhibited the corrosion reaction in aggressive acid medium. Impedance results indicate that the three organic compounds were adsorbed on the mild steel/solution interface, while polarization data show that the three compounds performed typically as a mixed-type inhibitor. A theoretical study of the adsorption performance of some of the components of Schiff base inhibitors was carried out in the basis of the density functional theory (DFT) and Monte Carlo simulations.     

5-CM-Salophen Schiff Base as an Effective Inhibitor for Corrosion of Mild Steel in 0.5 M HCl

5-CM-Salophen Schiff base was examined as an inhibitor for corrosion of mild steel in 0.5 M hydrochloric acid (HCl). The gravimetric data revealed corrosion inhibition effectiveness of the Schiff base even at low concentrations. Polarization measurements showed that the Schiff base is a mixed-type corrosion inhibitor. The polarization resistance (R_p) increased with increasing the Schiff base concentration. Also, the values of the double-layer capacitance decreased after addition of the inhibitor due to adsorption of the Schiff base on the surface. The inhibition mechanism was investigated by plotting the Langmuir adsorption isotherm and calculating the potential of zero charge (E_PZC) for mild steel samples. Scanning electron microscopy (SEM) analysis confirmed the results of the corrosion tests.     

Assessment of glycine derivative N-benzylidine-2((2-oxo-2-(10H-phenothiazine-10yl)ethyl)amino) acetohydrazide as inhibitor for mild steel corrosion in 1 M HCl solution: electrochemical and theoretical approach

Corrosion is a severe challenge which restricts the use of mild steel (MS) in various application where it comes in contact with aggressive chemicals and conditions. In this regard, different inhibitors were chosen, but environment unfriendliness of such inhibitors is a primary cause of concern. In this study, we present the systematic investigation of an environmentally benign compound, a glycine derivative N-benzylidine-2((2-oxo-2-(10H-phenothiazine-10yl)ethyl)amino) acetohydrazide (BPAA), as potential corrosion inhibitor at different temperature (30, 40, 50, and 60 °C). The investigation is accomplished by using the techniques including electrochemical polarization, electrochemical impedance spectroscopy (EIS), gravimetric, UV-visible spectrophotometry, FT-IR spectroscopy. The morphological characterization of the samples has been done by using high resolution SEM. The evaluated compound works as effective inhibitor for acid corrosion at substantially lower concentration and its adsorption on the MS surface was found to followed the Langmuir adsorption isotherm. Calculated thermodynamic parameters for adsorption unveiled a strong interaction amongst the inhibitor-MS surface. The electrochemical results revealed that the inhibitor act as mixed-type. The corrosion inhibition efficiency (IE) of the inhibitor was synergistically enhanced in the presence of surfactant additives sodium dodecyl sulfate and cetyl pyridinium chloride at quite lower concentration and showed that the addition of surfactant is an alternate strategy to enhance the IE and reduce the cost. The order of IE acquired from experimental results is successfully verified by theoretical calculations.     

羧甲基壳聚糖席夫碱的制备及抗菌性能研究

在超声波作用下,以自制的低分子量羧甲基壳聚糖与香草醛为原料,制备了低分子量羧甲基壳聚糖香草醛席夫碱。利用FI-IR对其结构进行了表征,研究了香草醛与羧甲基壳聚糖中氨基的反应摩尔比、反应温度、反应时间及超声波功率对产物氨基取代度的影响。结果表明：当香草醛与羧甲基壳聚糖中氨基的摩尔比为1∶0.8、反应时间为3 h、反应温度为70℃、超声波作用功率为70 W时,羧甲基壳聚糖香草醛席夫碱的氨基取代度可达到82.5%;将羧甲基壳聚糖席夫碱与羧甲基壳聚糖的抗菌性能进行了比较,发现羧甲基壳聚糖香草醛席夫碱对金黄葡萄球菌和大肠埃希菌的抑菌圈宽度分别比羧甲基壳聚糖的抑菌圈宽0.7 mm和0.5 mm。     

Adsorption and corrosion inhibition behaviour of N-(phenylcarbamothioyl)benzamide on mild steel in acidic medium

Corrosion inhibition property of N-(phenylcarbamothioyl)benzamide (PCB) on mild steel in 1.0 M HCl solution has been investigated using chemical (weight loss method) and electrochemical techniques (potentiodynamic polarization and AC impedance spectroscopy). The inhibition efficiencies obtained from all the methods are in good agreement. The thiourea derivative is found to inhibit both anodic and cathodic corrosion as evaluated by electrochemical studies. The inhibitor is adsorbed on the mild steel surface according to Langmuir adsorption isotherm. The adsorption mechanism of inhibition was supported by spectroscopic (UV-visible, FT-IR, XPS), and surface analysis (SEM-EDS) and adsorption isotherms. The thermodynamic parameter values of free energy of adsorption (ΔG_ads) reveals that inhibitor was adsorbed on the mild steel surface via both physisorption and chemisorption mechanism.     

In depth analysis of anti corrosion behaviour of eco friendly gum exudate for mild steel in sulphuric acid medium

The current research work was keen to examine the corrosion inhibition efficiency of mild steel (MS) in presence of aqueous extract of Araucaria heterophylla Gum (AHG) in 1?M H₂SO₄ medium. The phytoconstituents of the AHG were interpreted by GC-MS and corrosion inhibition efficiency was deduced using other techniques like weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Adsorption of inhibitor molecules on the mild steel surface was supported by Density Functional Theory (DFT) studies, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). It is seen from the results that the inhibitor exhibits optimum efficiency of 78.57% at 0.05% v/v on mild steel specimen in 1?M H₂SO₄ medium at room temperature. Tafel polarizations clearly show that the aqueous extract of AHG acts as a mixed type inhibitor. The change in the EIS parameters in presence of inhibitor is investigative of the protective layer formation of the mild steel surface. The adsorption is found to obey Langmuir adsorption isotherm. Thermodynamic and activation parameters for the corrosion inhibition process supported the physical adsorption mechanism.     

Pongamia Pinnata as a Green Corrosion Inhibitor for Mild Steel in 1N Sulfuric Acid Medium

Due to the harmful nature of the traditional inhibitors, in recent years researchers have an interest in using eco-friendly corrosion inhibitors. The plant extracts exhibit efficient corrosion inhibition properties due to the presence of a mixture of organic constituents starting from terpenoids to flavonoids. In the present study the inhibition of corrosion of mild steel in 1N H₂SO₄ solution using the leaf extract of Pongamia pinnata (P. pinnata) was investigated by the weight loss method, potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS) technique. Characterization of the leaf extract of P. pinnata was carried out using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GCMS) analysis. The effect of temperature and immersion time on the corrosion behavior of mild steel in sulfuric acid with different concentrations of P. pinnata was also studied. From the results it was found that the inhibition is mainly attributed to the adsorption of inhibitor molecules on the mild steel electrode surface. It was found that the adsorption of inhibitor molecules takes place according to the Langmuir, Temkin, and Freundlich adsorption isotherms. Kinetic as well as thermodynamic parameters were calculated, also confirming the strong interaction between inhibitor molecules and the electrode surface. The inhibition efficiency (I.E in %) was found to increase with increase in concentration of the inhibitor molecules and the maximum inhibition efficiency was attained at 100 ppm of the leaf extract. From the electrochemical studies it was found that the corrosion process was controlled by a mixed inhibition process and single charge transfer mechanism. Fourier transform infrared spectroscopy (FTIR) provided the confirmatory evidence for the adsorption of the extract molecules on the mild steel surface, which is responsible for the corrosion inhibition. Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) experiments also confirmed the presence of inhibitor molecules on the mild steel surface. From all these experimental results, it can be concluded that the leaf extract of P. pinnata acted as a good corrosion inhibitor for mild steel in 1N sulfuric acid medium even at lower inhibitor concentrations.     

Physicochemical Studies of 4-Substituted N-(2-Mercaptophenyl)-Salicylideneimines: Corrosion Inhibition of Mild Steel in an Acid Medium

A series of 4-substituted N-(2-mercaptophenyl)salicylideneimine Schiff bases were synthesized and investigated for corrosion inhibition of mild steel in hydrochloric acid medium. Inhibition through adsorption mechanism is proposed for these inhibitors, which is well supported by electrochemical impedance spectroscopy, the Langmuir adsorption isotherm and Scanning Electron Microscope morphologies of inhibited and uninhibited mild steel specimens. The negative ?G _ads indicates the spontaneous adsorption of the inhibitor on a mild steel surface. Among all the examined inhibitors, 5-bromo-N-(2-mercaptophenyl)salicylideneimine showed a higher inhibition efficiency. In order to reveal the usefulness of these Schiff bases as corrosion inhibitors under various circumstances, weight loss measurements were performed at various temperatures, acid concentrations and immersion times.     

Investigation of triazole derived Schiff bases as corrosion inhibitors for mild steel in hydrochloric acid medium

3,5-Diamino-1,2,4-triazole Schiff base derivatives and their inhibition efficiency, based on the effect of changing functional groups, were reported to establish a relationship between inhibitor efficiency and molecular structure using weight loss method, electrochemical and Fourier transform infrared spectral techniques. It was found that the molecules containing more electron donating groups have higher inhibition efficiency than the corresponding compounds with low electron donating groups. The results indicate that the order of inhibition efficiency of the triazole and its Schiff bases in solution and the extent of their tendency to adsorb on mild steel surfaces are as follows: vanilidine 3,5-diamino-1,2,4-triazole > furfuraldine 3,5-diamino-1,2,4-triazole > anisalidine 3,5-diamino-1,2,4-triazole > 3,5-diamino-1,2,4-triazole.     

THE EFFECT OF ENVIRONMENTALLY BENIGN FRUIT EXTRACT OF SHAHJAN (MORINGA OLEIFERA) ON THE CORROSION OF MILD STEEL IN HYDROCHLORIC ACID SOLUTION

The inhibition of the corrosion of mild steel in hydrochloric acid solution by the fruit extract of shahjan (Moringa oleifera) was studied using weight loss, electrochemical impedance spectroscopy (EIS), linear polarization, and potentiodynamic polarization techniques (Tafel). Inhibition was found to increase with increasing concentration of the extract. The effect of temperature, immersion time, and acid concentration on the corrosion behavior of mild steel in hydrochloric acid solutions with addition of extract was also studied. The inhibition occurred via adsorption of the inhibitor molecules on the mild steel surface obeying the Langmuir adsorption isotherm. Thermodynamic activation parameters such as activation energy, enthalpy (ΔH*), and entropy (ΔS*) of activation for corrosion process were calculated and discussed. The results obtained show that both chemical and physical adsorption of inhibitor molecules occur simultaneously and the fruit extract of shahjan (Moringa oleifera) could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid media.     

Experimental and theoretical study on amino acid derivatives as eco-friendly corrosion inhibitor on mild steel in hydrochloric acid solution

Amino acid derivatives, namely, 2-(2-oxo-2-phenothiazin-10-yl)ethylamino)-3-mercaptopropanoic acid (OPEM) and 2-(2-oxo-2-phenothiazin-10-yl)ethylamino)acetic acid (OPEA) were synthesized and investigated as inhibitors for mild steel corrosion in 15% HCl solution using the weight loss, polarization, and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency of both the inhibitors increased with increasing the temperature and concentration of inhibitor. The inhibitors OPEM and OPEA show corrosion inhibition efficiency of 97.5 and 95.8%, respectively, in 200?ppm concentration, at 333?K. Polarization studies showed that both studied inhibitors were of mixed type in nature. The adsorption of inhibitors on the mild steel surface obeys Langmuir adsorption isotherm and the surface of inhibited and uninhibited specimens were analyzed by scanning electron microscopy (SEM). The semiempirical AM1 method was employed for theoretical calculations and the obtained results were found to be consistent with the experimental findings.     

Acetyl thiourea chitosan as an eco-friendly inhibitor for mild steel in sulphuric acid medium

Acetyl thiourea chitosan polymer (ATUCS) has been synthesized and evaluated as corrosion inhibitor. The electrochemical behavior of mild steel in naturally aerated 0.5 M H₂SO₄ acid containing different concentrations of ATUCS has been studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements and surface examination via scanning electron microscope (SEM) technique. The results of EIS showed that the resistance (R_t) increases slightly with increasing immersion time indicating a slight decrease in corrosion rate of the steel with time. Also, the corrosion rate increases with either increasing temperature or decreasing the polymer concentration as observed by polarization technique. Electrochemical impedance spectroscopy measurements under open-circuit conditions confirmed well polarization results. ATUCS has shown very good inhibition efficiency (IE) in 0.5 M sulphuric acid solution reaches to 94.5% for 0.76 mM concentration. IE of this compound has been found to vary with the concentration of the polymer solution, immersion time and temperature.     

Nanosized scale roughness and corrosion protection of mild steel in hydrochloric acid solution and in the presence of Turmeric (Curcuma Longa) Extract as a green corrosion inhibitor: FTIR,polarization, EIS,SEM, EDS,AFM studies,and neural network modeling

In this study, the effect of Turmeric (Curcuma Longa) extract (TE), as an environmentally friendly corrosion inhibitor, was investigated in 1?M hydrochloric acid solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Additionally, the proposed inhibitor was characterized by FTIR, and surface morphology of mild steel after and before its exposure to acid solution in the presence and absence of 0.030?g/l TE inhibitor was examined through scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), and atomic force microscopy (AFM) techniques. Effect of TE concentration and temperature was evaluated. Then, thermodynamic parameters have been calculated and adsorption studies have been investigated. A good fit to Freundlich adsorption isotherm was obtained between surface coverage degree and inhibitor concentration. SEM and AFM images and EDS analysis of mild steel specimens in the absence and presence of the TE inhibitor confirmed the protective layer formation on metal surface. Finally, electrostatic interaction between main component of inhibitor and metal surface was investigated. Inhibition efficiency up to 92% has been achieved in 1?M acid solution containing 0.030?g/l inhibitor at 22?°C. Neural network modeling shows low stability of TE by increasing temperature and time.     

1-(2-Hydroxyethyl)-2-imidazolidinone as corrosion inhibitor of mild steel in 0.5 M HCl solution: thermodynamic,electrochemical and theoretical studies

The inhibition effect of 1-(2-Hydroxyethyl)-2-imidazolidinone (2-HEI) on mild steel (MS) corrosion in 0.5?M HCl solution was investigated at different inhibitor concentration and temperature by electrochemical experiments, such as linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and quantum chemical calculations. The inhibitor adsorption process on mild steel in 0.5?M HCl system was studied at different temperatures (20?°C–50?°C). Furthermore, the surface morphology of MS was also investigated with SEM in the absence and the presence of inhibitor. The adsorption of 1-(2-Hydroxyethyl)-2-imidazolidinone on MS surface is an exothermic process and this process obeys the Langmuir adsorption isotherm. The Quantum chemical findings are good agreed with the empirical data.     

Inhibitive effect of 4-amino-N-benzylidene-benzamide Schiff base on mild steel corrosion in HCl solution

Abstract

A newly Schiff base, 4-amino-N-benzylidene-benzamide (4-BAB) protection ability was synthesised from a condensation reaction of 4-aminobenzamide (4-AB) and benzaldehyde (BA). Adsorption and corrosion inhibition effect of this compound on mild steel (MS) in 1.0?M HCl solution were studied. The data obtained from measurments of this compound were compared with that of 4-AB and BA using many electrochemical, microscopic and hydrogen gas evolution techniques to clarify superiority of the Schiff base. Some thermodynamic parameters were calculated from experimental results and discussed. The value of ΔG_ads showed that adsorption of 4-BAB on MS from acidic solution obeys the Langmuir adsorption isotherm model. Surface SEM images of the MS specimens which were exposed to 1.0?M HCl solution in the absence and presence of the inhibitors showed that a homogeneous and protective inhibitor film forms on the metal surface, which hinder corrosive attack. It was concluded that synthesising the Schiff base improves protection ability with respect to related amine and aldehyde and the inhibitive action is in the order of 4-BAB > 4-AB?>?BA.

• Highlights

• 4-Amino-N-benzylidene-benzamide (4-BAB) is synthesized by condensation reaction between 4-aminobenzamide (4-AB) and benzaldehyde (BA)

• The inhibitor efficiencies calculated from all the applied methods are in agreement and are found to be in the order: 4-BAB >4-AB?>?BA

• The adsorption process of inhibitors on mild steel surface obeys the Langmuir adsorption isotherm

     

Synergistic corrosion inhibition effect of 1-ethyl-1-methylpyrrolidinium tetrafluoroborate and iodide ions for low carbon steel in HCl solution

Investigation into the corrosion inhibition of low carbon steel in 0.1-M HCl solution by 1-ethyl-1-methylpyrrolidinium (EMTFB) and the effect of KI addition on the inhibition efficiency was carried out using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy and surface analysis (scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX)) techniques. Results show that EMTFB suppresses low carbon steel dissolution in the corrosive environment. Inhibition efficiency increased with the increase in EMTFB concentration. Addition of iodide ions to EMTFB raises inhibition efficiency from 75 to 98%. PDP results indicate that EMTFB affects majorly anodic reactions while EMTFB + KI act as cathodic-type inhibitor. The adsorption of EMTFB onto low carbon steel surface is by physical adsorption mechanism and follows Langmuir adsorption isotherm model. SEM and EDAX results confirm the adsorption of EMTFB alone and in combination with KI onto the steel surface.     

4-Aminoantipyrine as an inhibitor of mild steel corrosion in HCl solution

4-aminoantipyrine (AAP) was tested as a corrosion inhibitor for mild steel in 2 M HCl solution using different techniques: weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that AAP is an inhibitor for mild steel in this medium. The inhibition was assumed to occur via adsorption of the inhibitor molecule on the metal surface. In the 20 to 60 C temperature range, the AAP adsorption follows the Flory–Huggins isotherm and/or the El-Awady et al. kinetic-thermodynamic model. The protection efficiency increases with increasing inhibitor concentration (in the range 10–310–2 M) but decreases with increasing temperature. The thermodynamic functions of dissolution and adsorption processes were calculated.     

Chitosan Biopolymer Schiff Base: Preparation,Characterization, Optical,and Antibacterial Activity

Natural biopolymer used for hydrogels has attracted increasing attention in the multifaceted areas of biomedical science and engineering. The authors prepared chitosan biopolymer Schiff base by solvent exchange method using a simple aliphatic crosslinker, crotanaldehyde. The identity of Schiff base was confirmed by UV-vis and Fourier-transform infrared spectroscopy. The chitosan Schiff base was evaluated by XRD, TGA, DSC, and SEM. The microbiological screening results demonstrated the antibacterial activity of Schiff base against Escherichia coli and Staphylococcus aureus bacteria. These results suggest that the newly prepared Schiff base may open a new perspective in biomedical applications.     

3-Methyl-4-amino-5-mercapto-1,2,4-triazole as corrosion inhibitor for 6061 Al alloy in 0.5?M sodium hydroxide solution

3-Methyl-4-amino-5-mercapto-1,2,4-triazole (MAMT) was synthesized, and its inhibition action on the corrosion of 6061 Al alloy in 0.5 M sodium hydroxide was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The effect of inhibitor concentration, temperature, and concentration of the corrosion medium on the inhibitor action was investigated. The surface morphology of the metal surface was investigated by scanning electron microscopy (SEM). The inhibition efficiency increased with the increase in the concentration of the inhibitor, but decreased with the increase in temperature. Both thermodynamic and kinetic parameters were calculated and discussed. The adsorption of MAMT on the base alloy was found to be through physisorption, obeying Langmuir’s adsorption isotherm. The results obtained from both the techniques were in good agreement with each other.