Class Of Corrosion Inhibitors Research Articles

Acalypha wilkesiana acid extract as a potential green inhibitor for corrosion of mild steel in acidic medium: Thermodynamics and kinetics study

The use of synthetic compounds as corrosion inhibitor is diminishing due to strict environmental regulations and toxic effects of the compounds on human beings and the environment. Consequently, there exists the need to develop a new class of corrosion inhibitors with low toxicity, eco-friendliness and good efficiency. Therefore, this study investigates the inhibitory potential of Acalypha wilkesiana (AWAE) extract on mild steel in 1M HCl using weight loss method. Experiments were performed by varying immersion period, concentration of the inhibitor and temperature. The results obtained showed a decrease in the corrosion rate of mild steel as the extract concentration increases while the inhibition efficiency increases with extract concentration. Effect of temperature on the inhibition efficiency showed an increase in inhibition efficiency with rise in temperature. The adsorption of the inhibitor on the mild steel surface in acid solution was found to obey the Langmuir adsorption isotherm. Calculated thermodynamic parameters revealed that the mechanism of the corrosion inhibition may be due to the chemical adsorption of the phyto-constituents on the surface of mild steel. Kinetic treatment of the data followed a first order reaction and the half-life values of the metal increase with increase in the extract concentration. Preliminary investigation of the phytochemical constituents showed that Acalypha wilkesiana contains tannin, flavonoid, saponin, alkaloid, steroid , terpenoid and some other compounds in trace quantity. FTIR results indicate that AWAE contains O and N atoms in functional groups and aromatic ring which meet the general consideration of a typical corrosion inhibitor.

An overview of the application of graphene-based materials in anticorrosive coatings

• Anti-corrosion performance of graphene and graphene based material coatings is reviewed. • Chemically modified graphene oxide emerged as new class of corrosion inhibitors. • Future development directions for graphene anti-corrosive coatings are anticipated. Graphene-based materials (GBMs) have an extensive range of potential uses, but over past ten years, interest in their usage as barrier layer or as reinforcements in coatings for corrosion prevention has developed. This review compiles the most recent information and seeks to provide authors with a broad synopsis of the most contemporary progresses in the application of GBMs in various anti-corrosion techniques.

Electrochemical and Molecular Dynamic Investigation of Some New Pyrimidine Derivatives as Corrosion Inhibitors for Aluminium in Acid Medium

A new class of corrosion inhibitors, namely, pyridine-2,6-diamine (PD) , pyrimidin-2-amine (PA), 6-amino-3,4-dihydropyrimidine-2(1H)-thione (ADT) and ethyl (R)-6-(4-chlorophenyl)-2-mercapto-4-methyl-1,6-dihydropyrimidine-5-carboxylate (EMMD) has been used. The influence of these pyridine-pyrimidine on the dissolution of aluminum in molar HCl has been investigated using impedance spectroscopy as well as potentiodynamic polarization and molecular dynamics simulations. Impedance spectroscopy data show that values of constant phase elements, CPE are decreased. Polarization resistance and protection efficiency increase with increasing concentration of pyridine-pyrimidine derivatives as the electric double layer increased. Electronic equivalent circuit of the investigated system is suggested. Potentiodynamic polarization results showed that these derivatives are mixed-type inhibitors with mainly cathodic action. Molecular simulations are used to simulate the adsorption of pyridine-pyrimidine, on the aluminum oxide substrate.

Grinding performance of hardened steel: a study about the application of different cutting fluids with corrosion inhibitor

The use of cutting fluid in the grinding process is crucial to guarantee quality in the products. However, most cutting fluids can cause disease to operators and damage the environment, which adds costs to the industry, as well as a deficit in the operator’s quality of life. In addition, the metalworking industry has as problem control corrosion in their parts; it demands to add the process of remove cutting fluid of the workpieces and add a protective oil on their surface. In this context, a new class of corrosion inhibitors that use water as a propagation medium, generically known as V-active® VCI, was formulated, which made it possible to develop, firstly, a cutting fluid with the addition of such inhibitor, called generically VCI 1, which would eliminate the process of degreasing and adding protective oil. Previous research has indicated the VCI 1 has an excellent performance in the grinding process, which promoted the development of two other new fluids (named generically VCI 2 and VCI EP) at a reduced market cost to make the product more competitive. In addition to the cost savings compared with the VCI 1, the VCI EP has the differential of an extreme pressure additive. It is noteworthy that the fluids in question pose no risk to humans and are biodegradable. Thus, the performance of these two new fluids with a corrosion inhibitor was verified in the grinding process of AISI 4340 steel with an aluminum oxide grinding wheel and the results were compared with the higher market cost V-active® VCI fluid and with a base fluid without the corrosion inhibitor. The comparison took place at three different feed rates (0.25, 0.50, and 0.75 mm/min). For each feed rate, the following were evaluated: surface roughness; roundness error, diametral grinding wheel wear, microhardness, optical microscopy, and acoustic emission, and the ground surface was analyzed using scanning electron microscopy (SEM). Therefore, useful information was obtained for the technological development of the rectification process, thus adding to scientific knowledge and dissemination of knowledge to society.

Theoretical and experimental electronic spectra of neutral, monoprotonated and diprotonated dapsone

Dapsone has been receiving growing interest due to it use as a new class of corrosion inhibitors, forming copolymers with aniline, pyrrole, diphenylamine and 4-aminodiphenylamine. The present work focuses on characterizing the theoretical and experimental electronic spectra of the neutral, monoprotonated and diprotonated dapsone. The theoretical electronic spectrum was obtained through the excited state characterization via time-dependent DFT theory. NBO analysis was carried out to identify the molecular orbitals involved in the detected experimental UV bands. The detected absorption wavelength values for the neutral dapsone were 292 and 258 nm (experiment), and 286.9 and 251.7 nm (theoretical). Concerning the protonated dapsone species, it was observed that the absorbance values were strongly dependent on pH, especially at pH between 1.0 and 4.0. As the pH of the solution decreases, the experimental band at 292 nm slowly decreases and shifts to 290 nm, while the absorption at 258 nm decreases until it disappears, and a new absorption band arises at 240 nm. While, when the basicity increases, the absorption spectra of dapsone do not change, but a regular red shift is noticed, and it is continued even up to pH 14.0. The red-shifted spectra may be due to the formation of a monoanion and/or dianion, but the isosbestic points were not constant.

Study of corrosion inhibition of C38 steel in 1\xa0M HCl solution by polyethyleneiminemethylene phosphonic acid

A new class of corrosion inhibitors, namely, polyethyleneiminemethylene phosphonic acid (PEIMPA), was synthesized and its inhibiting action on the corrosion of C38 steel in 1 M HCl at 30 °C was investigated by various corrosion monitoring techniques such as weight loss measurements, potentiodynamic polarization, linear polarization resistance (Rp), and surface analysis (SEM and EDX) which are used to characterize the steel surface. Weight loss measurements revealed that the presence of PEIMPA increases the inhibition efficiency by decreasing the corrosion rate. Tafel polarization study showed that the inhibitor acts as a mixed-type inhibitor. Adsorption of PEIMPA on the carbon steel surface was found to obey the Langmuir isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined and discussed. The SEM results showed the formation of protective film on the mild steel surface in the presence of PEIMPA. The results obtained from different tested techniques were in good agreement.

A Review on Environmentally-safe Corrosion deterrence of Metals in Various Media

<div><p><em>The present review gives a brief application of environmentally – safe corrosion inhibitors for various metals like aluminum, copper, mild steel, and zinc. Due to the enormous increase of industrial activities, a large amount of mineral acids are consumed. Therefore more number of metals gets corroded. These problems can be solved by using corrosion deterence. Although many chemical deterence are available most of them are highly virulent. So there is a need to explore a new class of corrosion inhibitors with good inhibition efficiency and that are environmentally - safe. Consequently, it can be achieved by using plant materials as corrosion inhibitors which are non-toxic, easily available and biodegradable.</em></p></div>

The Inhibition of Mild Steel Corrosion in Sulfuric Acid by New Dapsone Derivatives

Dapsone derivatives Viz., 4, 4’-sulfonylbis(N-((1H-pyrrol-2-yl)methylene)aniline) (SBPMA) and 2-dimethylamino-5-[(4-{4-[(4-dimethylamino-benzylidene)-amino]-benzenesulfonyl}-phenylimino)-methyl]-benzene (DBBPB), a new class of corrosion inhibitors have been synthesized and their corrosion inhibition efficiency on mild steel in 0.5 M H2SO4 was investigated by mass loss, Tafel polarization and AC impedance measurements. Potentiodynamic polarization studies showed that, these compounds behave as mixed type of corrosion inhibitors. The adsorption process was found to obey Langmuir isotherm model. Electrochemical impedance spectroscopy (EIS) studies revealed that polarization resistance (RP) increases and double layer capacitance (Cdl) decreases as the concentration of the inhibitors increases. Various thermodynamic parameters for the adsorption of inhibitors on mild steel were computed and discussed. FTIR, EDX and SEM analyses were performed to study the film persistency of the inhibitors.

Gemini surfactants: a new class of corrosion inhibitors for brass in 3N HNO3 solution

PurposeThe purpose of this paper is to present the results of some corrosion inhibition studies of brass in 3N HNO3 by gemini surfactants.Design/methodology/approachGemini surfactants namely: N‐trimethyl butane‐diyl‐1,2‐ethane‐bis‐ammonium bromide (BEAB), N‐hexane‐diyl‐1,2‐ethane‐bis‐ammonium bromide (HEAB), N‐dodecane‐diyl‐1,2‐ethane‐bis‐ammonium bromide (DDEAB) and N‐hexadecane‐diyl‐1,2‐ethane‐bis‐ammonium bromide (HDEAB) were synthesized in the laboratory and their influence has been investigated for controlling the dissolution of brass in 3N HNO3. Weight loss, potentiodynamic polarization and electrochemical impedance have been employed for the study. Weight loss experiments were performed as per standard method (ASTM, 1987). Potentiodynamic polarization studies were carried out using EG&G PARC potentiostat/galvanostat (model 173), universal programmer (model 175) and X‐Y recorder (model RE 0089) and impedance measurements were carried out with an EG&G PAR (model 5301 A) lock‐in‐amplifier, using an IBM computer.FindingsThe inhibition efficiency for all the gemini surfactants increases with increase in concentrations. The maximum inhibition efficiency of each inhibitor was achieved at 250 ppm concentration. The inhibition efficiency of all the inhibitors decreases on increasing the temperature from 30 to 50°C. The results of potentiodynamic polarization studies revealed that all the compounds were mixed type inhibitors and inhibit the corrosion of brass by blocking the active sites of the metal. The adsorption of the compounds on brass surface in 3N HNO3 has been found to obey the Langmuir adsorption isotherm.Originality/valueThe paper provides information regarding corrosion inhibition of brass in 3N HNO3, the mechanism of the inhibition on the basis of molecular structures of the inhibitors, activation energy and free energy of adsorption.

Calcium monofluorophosphate: a new class of corrosion inhibitors in NaCl medium

The effect of a new class of corrosion inhibitors, namely the monofluorophosphate of calcium, on the corrosion of iron, nickel, and copper in 3% NaCl solution has been investigated using potentiodynamic polarisation, measurement of open circuit potential, X-ray photoemission spectroscopy (XPS), and scanning electron microscope (SEM) techniques. The addition of an increasing concentration of calcium monofluorophosphate causes a shift of the corrosion potential in the positive direction, with a decrease of the anodic current density. The adsorption characteristics of this compound on the metal surface play a significant role in the inhibition process.

Calcium monofluorophosphate: a new class of corrosion inhibitors in NaCl medium

Calcium monofluorophosphate: a new class of corrosion inhibitors in NaCl medium

A corrosion inhibition study of iron by phosphonic acids in sodium chloride solution

The effect of a new class of corrosion inhibitors, namely piperidin-1-yl-phosphonic acid (PPA) and (4-phosphono-piperazin-1-yl) phosphonic acid (PPPA) on the corrosion of iron in NaCl medium has been investigated by electrochemical measurements. Potentiodynamic polarization studies clearly reveal the type of the inhibitor. The addition of increasing concentrations of phosphonic acids causes a shift of the pitting potential ( E pit) in the positive direction, indicating the inhibitive effect of the added phosphonic acid on the pitting attack. The potential of corrosion is moved towards negative values and the corrosion current is reduced. The values of the current are lower in the presence of PPA and PPPA. This is explained by the fact that most of the surface of the electrode is covered by the molecules adsorbed. PPPA has a strongly inhibitive effect on chloride pitting corrosion, it seems that the addition of the NCH 2PO 3H group (center adsorption) in the PPA para-position, giving PPPA, reinforces the active sites of this molecule and consequently increases its inhibition efficiency.

The influence of some Arylazobenzoyl acetonitrile derivatives on the behaviour of carbon steel in acidic media

The effect of a new class of corrosion inhibitors, namely, Arylazobenzoyl acetonitrile derivatives, on the corrosion of carbon steel in 2 M HCl and 1 M H 2SO 4 solutions has been studied by electrochemical polarisation methods (potentiodynamic, Tafel extrapolation and the determination of polarisation resistance). Generally, inhibition efficiency of the investigated compounds was found to increases with increasing concentration. Results obtained from both potentiodynamic and polarisation resistance techniques reveal that these compounds are good inhibitors and behave better in 2 M HCl than 1 M H 2SO 4. The adsorption of the compounds on the carbon steel in both acidic media follows a Langmuir adsorption isotherm.

Influence of 2,5-bis(4-dimethylaminophenyl)-1,3,4-thiadiazole on corrosion inhibition of mild steel in acidic media

An example of a new class of corrosion inhibitors, namely, 2,5-bis(4-dimethylaminophenyl)-1,3,4-thiadiazole (DAPT) was synthesized and its inhibiting action on the corrosion of mild steel in 1 M HCl and 0.5 M H2SO4 at 30 °C was investigated by various corrosion monitoring techniques. A preliminary screening of the inhibition efficiency was carried out using weight loss measurements. At constant acid concentration, inhibitor efficiency increases with concentration of DAPT and is found to be more efficient in 0.5 M H2SO4 than in 1 M HCl. Potentiostatic polarization studies showed that DAPT is a mixed-type inhibitor. The effect of temperature on the corrosion behaviour of mild steel in 1 M HCl with addition of DAPT was studied in the temperature range from 25 to 60 °C. Its was shown that adsorption is consistent with the Langmuir isotherm for 30 °C. The negative free energy of adsorption in the presence of DAPT suggests chemisorption of thiadiazole molecules on the steel surface.

Mannich Base Derivatives - A Novel Class of Corrosion Inhibitors for Cooling Water Systems

Limited resources of good quality water and the stringent environmental regulations on disposal of water warrant the operation of the present day's cooling water treatment systems with the highest practically feasible cycle of concentration (COC). However, with increase in COC, all the inorganic and organic constituents of the recirculating water increase proportionally thereby augmenting the possibility of failure of the system due to corrosion, scaling and fouling. Environmental concerns on the use of heavy metal based corrosion inhibitors have called for an effective alternative approach that is environmentally safe as well as cost-effective. The present investigation is aimed at evaluating the suitability of some Mannich base derivatives, namely, 4-methyl-2-fonnyl-6-(piperidine-1-yl methyl) phenol (MFPP) and 4-methyl2-formyl-6-(molpholine-1-yl methyl) phenol (MFMP), synthesized in our laboratory, as corrosion inhibitors for cooling water treatment systems, under simulated laboratory conditions. Mild steel was used as the substrate material and the inhibition efficiency of MFPP and MFMP were assessed under varying conditions of temperature, pH and dissolved salts. Both compounds exhibit good inhibition towards the corrosion of mild steel under varying experimental conditions. The other interesting feature about these compounds is their ability to perform as a self-indicator in the cooling water system based on the existence of their chemical structure under acidic and alkaline conditions, respectively, exhibiting a colourless and fluorescent green colour. This inherent property of these compounds is very useful in continuous monitoring and control of cooing water systems. Besides it also helps in identifying critical conditions like tolerance level of the acid dosage, given to prevent scaling, which would otherwise cause excessive metal attack and ultimately lead to a premature failure of the system.

Thioamidines as novel class of corrosion inhibitors

Abstract Four nitrogen substituted thiobisformamidines – phenyl thiobisformamidines (PTBF), tolyl thiobisformamidines (TTBF), anisidyl thiobisformamidines (ATBF), and 4-chlorophenyl thiobisformamidines (CPTBF) – were synthesised and their corrosion inhibiting behaviour for mild steel in 1M, 3M, and 5M HCl was studied. The optimum concentration of these compounds for maximum inhibition efficiency was determined by weight loss methods. All the investigated thiobisformamidines gave more than 95% inhibition in the presence of 1M HCl, and CPTBF showed the best inhibition efficiency (98% in 5M HCl). Potentiodynamic polarisation studies revealed that all the tested compounds are of mixed inhibitor type. The adsorption of these compounds from the acid solution obeyed Temkin's adsorption isotherm. All the inhibitors were able to reduce hydrogen permeation through the steel surface and their performance was enhanced by the addition of iodide ions. Electron impedance spectroscopic studies were also carried out in or...

3,5-bis(n-Hydroxyphenyl)-4-amino-1,2,4-triazoles and 3,5-bis(n-aminophenyl)-4-amino-1,2,4-triazoles: a new class of corrosion inhibitors for mild steel in 1m HCl medium

A new class of corrosion inhibitors, namely, 3,5-bis(n-hydroxyphenyl)-4-amino-1,2,4-triazoles and 3,5-bis(n-aminophenyl)-4-amino-1,2,4-triazoles which have been labelled n-HPAT and n-APAT has been synthesized. The influence of aminotriazoles on the corrosion of mild steel in 1m HCl has been studied using weight loss and electrochemical impedance spectroscopy. Results obtained show that these compounds are very good anodic inhibitors. The adsorption of these aminotriazoles is found to obey Langmuir adsorption isotherm.

Inhibiting effects of 3,5-bis(n-pyridyl)-4-amino-1,2,4-triazoles on the corrosion for mild steel in 1 M HCl medium

A new class of corrosion inhibitors, namely, 3,5-bis(n-pyridyl)-4-amino-1,2,4-triazoles (n-PAT) has been synthesised and its inhibiting action on the corrosion of mild steel in 1 M HCl has been investigated by various corrosion monitoring techniques such as corrosion weight loss tests and electrochemical impedance spectroscopy. The electrochemical study reveals that these compounds are anodic inhibitors. The adsorption of (n-PAT) on the steel surface obeys the Langmuir adsorption isotherm.

CHEMICAL STRUCTURE AND ADSORPTION OF ORGANIC MOLECULES AT THE POLARIZED MERCURY–ELECTROLYTE INTERFACE

Previous studies on electrochemical adsorption at mercury of a series of heterocyclic and aromatic nitrogen bases and their respective conjugate ions by electrocapillary measurements are extended to simple saturated heterocyclic compounds containing oxygen and to aliphatic alcohols with different degrees of unsaturation. Adsorption isotherms for various electrode potentials are derived, and standard electrochemical free energies of adsorption are calculated as before, to relate the influence of molecular and electronic structure of the adsorbates on the properties of the electrical double layer. Oxygen as the heteroatom in cyclic compounds and in the hydroxyl group of the alcohols plays a distinct role in the characteristics of metal–adsorbate and adsorbate–solvent interactions through its higher electronegativity as compared with nitrogen. Considerations of the different geometric areas of adsorbed molecules due to isomerism of the saturated heterocyclic compounds, and the varying unsaturation of the alcohols lead to more realistic interpretation of orientation effects, surface coverages, and degrees of adsorbability. Improvement in pressure control in the electrocapillarometer assembly gives better precision in surface tension measurements. Some preliminary results on the adsorption of furfurylamines and related analogues which constitute a newly available class of corrosion inhibitors are briefly discussed.