Experimental and computational chemical studies on the corrosion inhibitive properties of metamizole sodium pharmaceutical drug compound for CS in hydrochloric acid solutions

The effect of sodium metamizole as a corrosion inhibitor for carbon steel (CS) in 1 M hydrochloric acid at various concentrations was studied by using chemical (weight loss, WL) and electrochemical [electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP)] methods. The results of WL showed that the effectiveness of sodium metamizole as a CS preservative in a hydrochloric acid solution at room temperature raised by improvement of the concentration of the inhibitor and reached 82.87% at 300 ppm and 25 °C. The effect of temperature on the CS was studied and the thermodynamic parameters of activation and adsorption were computed and discussed. The results showed that the inhibition efficiency (IE) decreases with increasing temperature, suggestive of physisorption. This was collaborated by values of activation energy, which are all below 80 kJ mol^?1 and free energy which are below 20 kJ mol^?1. The adsorption mechanism was coherent with Langmuir adsorption model. Results of the PDP revealed that the inhibitor was adsorbed on CS surface by mixed type of behavior. Furthermore, EIS revealed the dip in the values of double-layer capacitance and improvement in the charge transfer resistance with increased dose of sodium metamizole. Surface examinations were performed using altered techniques. The theoretical studies were calculated to confirm the validity of the practical results and the results of both were compared with each other, demonstrating the validity of the results obtained.     

Corrosion inhibition of mild steel by highly stable polydentate schiff base derived from 1,3- propanediamine in aqueous acidic solution

Recently, the hydrolysis of Schiff bases under experimental conditions gives suspicion for their corrosion inhibition performance. The current study employs a stable Schiff base namely, 2,2′-{propane-1,3-diylbis[azanylylidene (E) methanylylidene]}bis(6-methoxyphenol) (LPD) as corrosion inhibitor for mild steel (MS) in 1 M HCl solution. The presence of the characteristic peak of the imine group in UV-visible spectra was taken as an indicator for LPD stability in acidic media. The inhibition action was examined using electrochemical techniques including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) besides gravimetric measurement. The inhibition efficiency reached 95.93 % for 0.75 mM LPD after 24 h of immersion at 25 °C. This high efficiency is owing to the presence of the characteristic imine group and other heteroatoms and π- electrons of the aromatic benzene rings. The mechanism of inhibition depends on adsorption phenomena on mild steel surface which obeys Langmuir isotherm model. The calculated values of adsorption equilibrium constant (K_ads), adsorption free energy ΔG_ads, adsorption enthalpy ΔH_ads and adsorption entropy ΔS_ads indicated spontaneous exothermic adsorption process of both physical and chemical nature. By rising temperature, the inhibition efficiency of LPD was decreased. The calculated activation energy was increased as the concentration of LPD increased. LPD was considered as a mixed-type inhibitor as indicated from PDP measurements. The obtained surface morphology and composition analysis using SEM/EDS, AFM and FTIR techniques ensures the high efficiency of LPD as corrosion inhibitor.     

Experimental and theoretical studies of carbon steel corrosion protection in phosphoric acid solution by expired lansoprazole and rabeprazole drugs

The effects of expired lansoprazole and rabeprazole on the corrosion protection of carbon steel in phosphoric acid (3.0 ?M) solution were examined by Tafel polarization and electrochemical impedance spectroscopy (EIS). Lansoprazole and rabeprazole concentrations (0.5, 1.0, 5.0 and 10 ?mM) in acid solution were raised, which improved corrosion prevention. Both lansoprazole and rabeprazole as the mixed inhibitors retarded the anodic and cathodic processes, as indicated by polarization data. With the increasing temperature in the range of 25–55 ?°C, the inhibition efficiency drops from 92.9% to 69.3% for lansoprazole and from 94.8% to 74.2% for rabeprazole. The major decrease in the inhibition efficiency with ascending temperature proved the physisorption of the drugs. The activation energies for carbon steel corrosion in H₃PO₄solution were enhanced from 41.6 ?kJ ?mol^?1 to 81.9 ?kJ.mol^?1and 85.9 ?kJ ?mol^?1 for lansoprazole and rabeprazole, respectively. The influence of temperature on the corrosion process of carbon steel in the acid medium was used to derive the thermodynamic quantities of corrosion. The adsorption of both lansoprazole and rabeprazole on carbon steel followed the Langmuir adsorption isotherm. The polarization data yielded outcomes that were consistent with the results arising from impedance measurements. The theoretical study of both lansoprazole and rabeprazole was done by a density functional theory (DFT) approach to realize the effects of molecular structure on their inhibitive action. Both lansoprazole and rabeprazole contain a higher E_HOMO, a lower E_LUMO and a lower energy gap than some inhibitors earlier reported as good corrosion inhibitors in the literature.     

On the corrosion inhibition of iron in hydrochloric acid solutions,Part I: Electrochemical DC and AC studies

The inhibitive action of 4-methyl pyrazole (4MP) against the corrosion of iron (99.9999%) in solutions of hydrochloric acid has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). At inhibitor concentration range (10^?3–10^?2 M) in 1.0 M acid, the results showed that 4MP suppressed mainly the anodic processes of iron corrosion in 1.0 M HCl by adsorption on the iron surface according to Temkin adsorption isotherm. Both potentiodynamic and EIS measurements reveal that 4MP inhibits the iron corrosion in 1.0 M HCl and that the efficiency increases with increasing inhibitor concentration. Data obtained from EIS were analyzed to model the corrosion inhibition process through an equivalent circuit.     

Adsorption and inhibitive properties of aminobiphenyl and its Schiff base on mild steel corrosion in 0.5 M HCl medium

Electrochemical measurements were performed to investigate the effectiveness and adsorption behaviour of aminobiphenyl (Aph) and 2-(3-hydroxybenzylideneamino)biphenyl (Aph-S), as corrosion inhibitors for mild steel (MS) in 0.5 M HCl solution. Potentiodynamic polarization, linear polarization resistance (LP) and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behaviour in the absence and presence of different concentrations of Aph and Aph-S. In order to gain more information about adsorption mechanism the AC impedance technique was used to evaluate the potential of zero charge (PZC) from polarization resistance (R_p) versus voltage (E) plot. Potentiodynamic polarization measurements showed that Aph act as cathodic type inhibitor where as Aph-S act mixed type. The inhibition efficiency (IE%) increases with increasing concentration of compounds and reached 92.6% for Aph and 97.2% for Aph-S at 5 × 10⁻³ M. Double layer capacitance (C_dl) and polarization resistance (R_p) values are derived from Nyquist plots obtained from AC impedance studies. The experimental data fit Langmuir isotherm for both Aph and Aph-S, and from the adsorption isotherm some thermodynamic data for the adsorption processes are calculated and discussed. The effect of exposure time on the corrosion behaviour of mild steel in the absence and presence of inhibitor over 168 h was also studied.     

Experimental and theoretical investigations of adsorption of fexofenadine at mild steel/hydrochloric acid interface as corrosion inhibitor

The present study examines the effect of fexofenadine, an antihistamine drug, on corrosion inhibition of mild steel in molar hydrochloric acid solution using different techniques under the influence of various experimental conditions. Results revealed that fexofenadine is an effective inhibitor and percent inhibition efficiency increased with its concentration; reaching a maximum value of 97% at a concentration of 3.0 × 10⁻⁴ M. Fourier-transform infrared spectroscopy (FTIR) observations of steel surface confirmed the protective role of the studied drug. Polarization studies showed that fexofenadine is a mixed-type inhibitor. The adsorption of the inhibitor on mild steel surface obeyed the Langmuir adsorption isotherm with free energy of adsorption (∆G°_ads) of −40 kJ mol⁻¹. Energy gaps for the interactions between mild steel surface and fexofenadine molecule were found to be close to each other showing that fexofenadine has the capacity to behave as both electron donor and electron acceptor. The results obtained from the different corrosion evaluation techniques are in good agreement.     

Influence of pyridazine derivative on corrosion inhibition of mild steel in acidic media

The inhibition behavior of 6-methyl-4,5-dihydropyridazin-3(2H)-one (MDP) on corrosion of mild steel in 1 M HCl and 0.5 M H₂SO₄ was investigated using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. The results indicated that the corrosion inhibition efficiency depends on concentration, immersion time, solution temperature, and the nature of the acidic solutions. It is also noted that MDP is at its the most efficient in 1 M HCl and least in 0.5 M H₂SO₄. The effect is more pronounced with MDP concentration. It is found that the inhibition efficiency attains 98 % at 5 × 10^?3 M in 1 M HCl and 75 % at 5 × 10^?2 in 0.5 M H₂SO₄. Polarization measurements showed that the MDP acts as a mixed inhibitor. EIS diagrams showed that the adsorption of MDP increases the transfer resistance and decreases the capacitance of the interface metal/solution. From the temperature studies, the activation energies in the presence of MDP were found to be superior to those in uninhibited medium. Finally, a mechanism for the adsorption of MDP was proposed and discussed.     

Indole‐3‐acetic acid and N‐acetyltryptophan corrosion inhibition effects on mild steel in 1 M hydrochloric acid solution

Corrosion inhibition of indole‐3‐acetic acid and N‐acetyl tryptophan on carbon steel was investigated using polarization and electrochemical impedance spectroscopy (EIS). Polarization results revealed that corrosion inhibitors could reduce the rate of cathodic and anodic reactions on metal surface. EIS analysis showed inhibition efficiency of indoles increases by increasing the inhibitor concentration. The maximum inhibition efficiency was 97% and 80% in solutions containing 10 mM indole‐3‐acetic acid and 10 mM N‐acetyl tryptophan, respectively. The adsorption of inhibitors was found to follow Langmuir isotherm. Adsorption and film formation of inhibitors on the metal substrate were confirmed by calculating thermodynamic adsorption parameter (ΔG⁰_ads) and characterization of exposed metals' surface through contact angle measurements. Copyright © 2014 John Wiley & Sons, Ltd.     

Inhibition of CTAB on the Corrosion of Mild Steel in Hydrochloric Acid

The inhibition effect of cetyl trimethyl ammonium bromide (CTAB) on the corrosion of mild steel in 1.0 mol L^?1 hydrochloric acid (HCl) has been studied at different temperatures (25–60°C) by weight loss and potentiodynamic polarization methods. The results reveal that CTAB behaves as an effective inhibitor in 1.0 mol L^?1 HCl, and the inhibition efficiency increases with the inhibitor concentration. Polarization curves show that CTAB is a mixed-type inhibitor in hydrochloric acid. The results obtained from weight loss and polarizations are in good agreement. The effect of immersion time on corrosion inhibition has also been examined and is discussed. The adsorption of inhibitor on mild steel surface obeys the Langmuir adsorption isotherm equation. Thermodynamic parameters have been obtained by adsorption theory. The inhibition effect is satisfactorily explained by the parameters.     

Corrosion inhibition performance of 2-ethyl phenyl-2, 5-dithiohydrazodicarbonamide on Fe (110)/Cu (111) in acidic/alkaline solutions: Synthesis,experimental, theoretical,and molecular dynamic studies

Herein, 2-ethyl phenyl-2,5-dithiohydrazodicarbonamide (2EPDCA) was synthesised and tested as a corrosion inhibitor for mild steel (MS) and copper (Cu) in 1 M HCl and 3.5% NaCl, respectively. Fourier transform infrared spectroscopy (FT-IR) and (NMR) nuclear magnetic resonance (¹H, ¹³C) were used to identify the chemical structure. Both experimental and computational approaches have been conducted to evaluate inhibitor efficiency on both metal systems. The electrochemical results showed that the 2EPDCA inhibition efficiency for MS systems was 95% at 1 × 10^?2 M, while in copper systems it was 97.5% at 1 × 10^?2 M. The Langmuir adsorption isotherm was fitted using adsorption surface coverage data, and for inhibitor in both systems, the kind of adsorption was mixed (physisorption and chemisorption). Through scanning electron microscopy (SEM), EDX, and atomic force microscopy (AFM) tests, we have confirmed the presence of the inhibitor molecules on the metal surface in both systems. Quantum chemistry simulations indicate that the superior corrosion inhibition efficacy of 2EPDCA on copper compared to mild steel surfaces is attributable to the former's greater electron donating propensity on copper. The adsorption of 2EPDCA molecules on Fe (110) and Cu (111) surfaces was further verified by molecular dynamic simulations, with the former having a greater adsorption energy. The results indicate that the corrosion inhibitor was effective even in harsh conditions, and it can be thought of as a novel corrosion inhibitor for mild steel and copper that provides good protection.     

Adsorption Behavior and Inhibition Corrosion Effect of Sodium Carboxymethyl Cellulose on Mild Steel in Acidic Medium

The effect of sodium carboxymethyl cellulose (Na-CMC) on the corrosion behavior of mild steel in 1.0 mol·L⁻¹ HCl solution has been investigated by using weight loss (WL) measurement, potentiodynamic polarization, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) methods. These results showed that the inhibition efficiency of Na-CMC increased with increasing the inhibitor concentration. Potentiodynamic polarization studies revealed that the Na-CMC was a mixed type inhibitor in 1.0 mol·L⁻¹ HCl. The adsorption of the inhibitor on mild steel surface has been found to obey the Langmuir isotherm. The effect of temperature on the corrosion behavior of mild steel in 1.0 mol·L⁻¹ HCl with addition of 0.04% of Na-CMC has been studied in the temperature range of 298–328 K. The associated apparent activation energy (E^*_a) of corrosion reaction has been determined. Scanning electron microscopy (SEM) has been applied to investigate the surface morphology of mild steel in the absence and presence of the inhibitor molecules.     

Carmine and Fast Green as Corrosion Inhibitors for Mild Steel in Hydrochloric Acid Solution

The inhibition action of carmine and fast green dyes on corrosion of mild steel in 0.5 M HCl was investigated using mass loss, polarization and electrochemical impedance (EIS) methods at 300 K. The inhibition efficiency was found to increase with increasing concentration of the inhibitors. The inhibition efficiency of fast green (%η - 98) is higher than that of carmine (%η - 92) and found to be maximum in 1 × 10^-3 M solution. The inhibitors act as mixed type with predominant cathodic effect. The inhibitors were adsorbed on the mild steel surface according to the Temkin adsorption isotherm. The surface morphology of the mild steel specimens was evaluated using SEM images.     

Corrosion inhibition of carbon steel immersed in a 1 M HCl solution using benzothiazole derivatives

Corrosion inhibition effect of 2-mercaptobenzothiazole (MBT) and 2-aminobenzothiazole (ABT) compounds on ST-37 carbon steel in 1 M hydrochloric acid solution was investigated by electrochemical impedance spectroscopy (EIS), and it was observed that both of these compounds have corrosion inhibition effect on carbon steel. Evaluation of electrochemical behavior in test solutions showed that by increasing the immersion time from 15 to 300 min, corrosion resistance of samples is increased and at the same immersion time MBT has a better corrosion inhibition in comparison to ABT. AFM technique was performed for MBT and ABT. The results of calculations showed superior inhibition efficiency of MBT in comparison to ABT. This can cause easier protonation and consequently adsorption on the metal surface occurs.     

Corrosion behavior of the steel used as a huge storage tank in seawater

Open-circuit potential (OCP), polarization curve, and electrochemical impedance spectroscopy (EIS) measurement were used to investigate the corrosion behaviors of high-strength low-alloy (HSLA) steel and mild steel in seawater. Both steels were used in the construction of a huge oil storage tank. The OCP results show that the HSLA steel quickly reached more negative E _OCP values than the mild steel. Polarization curve results reveal that the HSLA steel exhibits higher corrosion currents and more negative corrosion potentials than the mild steel. EIS measurements reveal that both steels exhibit similar corrosion behaviors up to 144 h, one increased capacitance loop can be shown in EIS diagrams. The mild steel presents higher corrosion resistances than the HSLA steel at former stage, which is associated with the effect of the grain size. After 240 h of immersion, both steels present different corrosion behaviors. The EIS diagrams exhibit two capacitance arcs for the HSLA steel and one capacitance arc for the mild steel, which is due to the formation of intact corrosion scales on the electrode surface of the HSLA steel as to introduce a new reaction interface. The HSLA steel exhibits higher corrosion resistances than the mild steel at latter stage of experiment, which is ascribed to the synthetic actions of residual Fe₃C and the protective property of corrosion products.     

Electrochemical investigation of corrosion and corrosion inhibition of iron in hydrochloric acid solutions

The inhibition effect of 1-methyl pyrazole (MPA) on the acidic corrosion of iron in 1.0 M HCl was studied at different concentrations (10^?3–10^?2 M) by potentiodynamic polarization and electrochemical impedance spectroscopy, and EIS measurements. It is found from the polarization studies that methyl pyrazole (MPA) behaves mainly as anodic inhibitor in HCl. Values of polarization resistance (R_p) and double layer capacitance (C_dl) in the absence and presence of MPA in 1.0 M HCl are determined. The adsorption of MPA on iron surface from HCl is found to obey Temkin adsorption isotherm.     

Quantum chemical study of inhibition of the corrosion of mild steel in 1 M hydrochloric acid solution by newly synthesized benzamide derivatives

The inhibitory effect of some new synthesized benzamide compounds on corrosion of mild steel in 1 M HCl solution has been studied by use of weight loss measurements and the electrochemical techniques potentiodynamic polarization and electrochemical impedance spectroscopy. The inhibiting action is more pronounced with increasing concentration. Inhibition efficiency is maximum (approximately 99 %) at 10^?3 M. Polarization measurements also show that the compounds act as mixed inhibitors. The cathodic curves indicate that reduction of protons at the mild steel surface occurs as a result of a pure activating mechanism. EIS measurements reveal increased transfer resistance with increasing inhibitor concentration. The presence of heteroatoms increases inhibition efficiency without causing a drastic change in adsorption mechanism, which follows the Langmuir isotherm model. Significant correlations were obtained between inhibition efficiency with the chemical indexes calculated, by use of the standard software Gaussian03, on the basis of density functional theory (DFT) at the B3LYP/6-31G** level of theory, indicating that variation of inhibition with inhibitor structure may be explained in terms of electronic properties. The effect of temperature on the corrosion behaviour of steel in 1 M HCl without and with inhibitors at 10^?3 M was studied in the temperature range from 308 to 333 K, and the associated activation energy was determined.     

Comparative inhibition study of mild steel corrosion in hydrochloric acid by new class synthesised quinoxaline derivatives: part I

7-Cchloro-3-(4-methoxystyryl)quinoxalin-2(1H)-one (CMOSQ) and 7-chloro-2-(4-methoxyphenyl)thieno(3.2-b)quinoxaline (CMOPTQ) have been investigated for mild steel corrosion in 1 M HCl at different concentrations using weight loss measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy methods. Generally, inhibition efficiency of the investigated compounds was found to depend on inhibitor concentration and their structures. Comparitive results showed that CMOPTQ was the best inhibitor and the inhibition efficiency increased with increasing the concentration and attained 86 and 87 % at 10^?3 M of CMOPTQ and 10^?3 M of CMOSQ, respectively. Potentiodynamic polarization studies clearly reveal that these inhibitors act essentially as cathodic-type inhibitors. The inhibition efficiency increases with immersion time and reaches 95 % CMOPTQ at 24 h. The electrochemical impedance spectroscopy result showed that these compounds act by formation of film.     

Corrosion inhibition of steel in molar HCl by triphenyltin2–thiophene carboxylate

The effect of triphenyltin2–thiophene carboxylate (TTC) on the corrosion of steel in hydrochloric acid medium was studied using gravimetric, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor to reach 97% at 10^?3 M. Polarisation study shows that TTC is an efficient inhibitor and acts as a mixed-type inhibitor. EIS results indicate the increase of resistance transfer (R_T) and the decrease of double layer capacitance (C_dl) with TTC concentration. Triphenyltin2–thiophene carboxylate molecules lead to the formation of a protective layer on the surface of steel. The inhibitor is adsorbed on the steel surface according to Langmuir isotherm.     

Monitoring corrosion and corrosion control of low alloy ASTM A213 grade T22 boiler steel in HCl solutions

Rates of corrosion of low alloy ASTM A213 grade T22 boiler steel were monitored in aerated stagnant 0.50 M HCl solutions at different temperatures (283–303 K) using Tafel extrapolation method and the non-destructive electrochemical frequency modulation (EFM) technique, complemented with XPS examinations. Serine (Ser) was introduced as a corrosion-safe inhibitor. Corrosion rates (in μm y^?1) obtained from these two methods was in good agreement. Tafel plots showed that Ser acted mainly as a cathodic-type inhibitor. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. XPS examinations of the electrode surface confirmed the existence of such adsorbed film. The inhibition efficiency increased with increase in Ser concentration, while it decreased with temperature, suggesting physical adsorption. Activation energies have been calculated in the absence and presence of various concentrations of Ser by measuring the temperature dependence of the corrosion rate obtained from the two methods employed. It was found that the activation energy in the presence of Ser is higher than that in bare HCl solution. The adsorptive behaviour of Ser followed Temkin-type isotherm. The standard free energy of adsorption was estimated to be ?25 kJ mol^?1 at 303 K. These results confirmed the occurrence of physical adsorption.     

Hierarchically porous tobacco midrib-based biochar prepared by a simple dual-templating approach for highly efficient Rhodamine B removal

High volatile matter contents in the feedstock could promote the development of porous structures and the reactivity of biochar. Herein, tobacco midrib with high volatile matter contents was used to prepare biochar by a dual-templating approach with mild activators (K₂C₂O₄·H₂O, CaCO₃). The characterizations of textural properties indicated that tobacco midrib-based biochar possessed numerous meso-, micro-, and macro-pores, specific surface area reached 1841.9 m² g^?1. As a dye adsorbent, the adsorption capacity of this biochar towards Rhodamine B reached 588.7 mg g^?1. After recycling 5 times, it still retained over 90% of its initial adsorption capacity. Moreover, thermodynamic parameters assessed with full vańt Hoff equation confirmed that dye molecules replace water molecules connected on biochar surface during the adsorption according to negative heat capacity change (-3.9 kJ mol^?1 K^?1), ΔH⁰ (–22.1 kJ mol^?1) and ΔS⁰ (0.3 kJ mol^?1) revealed that the adsorption process of Rh B by TMB was exothermic and the disorder of the solid–liquid interface increased. Overall, this research provides a mild and effective approach to modifying biochar from special tissue of agriculture waste and an insight into the process of dye adsorption on biochar from thermodynamics.