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This paper aims to evaluate the inhibition efficiency of thiadiazole derivatives, such as 2,5-dimercapto-1,3,4-thiadiazole (DMTD), 5-methly-2-mercapto-1,3,4-thiadiazole (MMTD) and 2,5-dithiododecyl-1,3,4-thiadiazole (DDTD), in 50 mg/L hydrogen sulfide for silver strip.

Evaluation was carried out by corrosion-inhibiting test, electrochemical measurement and surface analysis techniques. 3D surface profiler, atom force microscopy, scanning electron microscopy and energy-dispersive X-ray analysis were applied and finally confirmed the existence of the adsorbed film.

The electrochemical measurement showed that the inhibition efficiency increases with increasing inhibitor concentration in 50 mg/L hydrogen sulfide solution, while the corrosion rate and the corrosion current decrease. Weight-gained measurements also indicated that inhibitor decreases the corrosion rate in the studied solution. The adsorption of DMTD and MMTD on the silver surface obeys Temkin’s adsorption isotherm, but the adsorption of DDTD follows Langmuir’s adsorption isotherm. That means that the inhibition mechanism is different between DMTD, MMTD and DDTD. The ΔG0_ad values of DMTD, MMTD and DDTD were −37.47, −37.29 and −38.69 kJ/mol, respectively. It showed that there was an adsorption bond between silver surface and inhibitor, and the adsorption belongs to chemical adsorption.

The inhibitors have an excellent inhibition efficiency, and the best inhibition efficiency is 91.76 per cent. Inhibitors can effectively inhibit metal corrosion in the oil and gas.

The purpose of this paper is to investigate the effects of several azole derivatives on the corrosion inhibition of irradiated and non‐irradiated plain carbon steel in 0.5 M nitric acid (HNO₃) solutions at 30‐60°C and to study the mechanism of their inhibitive action.

The inhibition efficiency was evaluated by means of weight‐loss determinations and polarization techniques at different temperatures. The type of adsorption isotherm, inhibition efficiency, surface coverage and kinetic data were determined.

The results showed that azole derivatives inhibit the corrosion of irradiated and non‐irradiated carbon steel in acidic solution. The inhibition efficiency increased with the inhibitor concentration and was greater in the case of irradiated carbon steel than for the non‐irradiated one. Kinetic parameters were calculated. The adsorption of inhibitors obeyed the Temkin Isotherm model. Thermodynamic parameters of activation were calculated in the presence of inhibitors.

Electrochemical studies such as electrochemical impedance spectra will throw more light on the mechanism of inhibition.

Azole derivatives can be used as inhibitors in acid medium and addition of halides can improve their inhibition efficiency.

The investigation revealed the possible application of azole derivatives as environmentally friendly inhibitors for corrosion prevention under specific conditions.

The purpose of this paper is to carry out laboratory studies of the inhibition effect of tyrosine (Tyr) on the corrosion of low chromium alloy steel (ASTM A213 grade T22) in 7 wt percent sulfamic acid solutions.

The corrosion inhibitive effect of Tyr was investigated using electrochemical impedance spectroscopy (EIS) and the new technique electrochemical frequency modulation (EFM).

It was found that the inhibition efficiency increased with increasing inhibitor concentration, while a decrease was detected with the rise of temperature and stirring speed. The corrosion inhibition is due to physical adsorption of Tyr on the steel surface. Adsorption of the inhibitor molecule, onto the steel surface follows the Temkin's adsorption isotherm.

The obtained results from both methods (EIS and EFM) at different experimental conditions were in high agreement and almost similar. This is an indication that the EFM technique can be used efficiently for monitoring the corrosion inhibition under the studied conditions.

2‐undecane‐5‐mercapto‐1‐oxa‐3, 4‐diazole (UMOD), 2‐heptadecene‐5‐mercapto‐1‐oxa‐3, 4‐diazole (HMOD) and 2‐decene‐5‐mercapto‐1‐oxa‐3, 4‐diazole (DMOD) were synthesized in the laboratory and their influence on the inhibition of corrosion of mild steel in 1N HCI and 1N H₂SO₄ was investigated by weight‐loss and potentiodynamic polarization techniques. The inhibition efficiency of these compounds was found to vary with concentration, temperature and immersion time. Good inhibition efficiency (IE) was evidenced in both acid solutions, remaining high (> 90 per cent) even at the concentration of 25ppm. The adsorption of these compounds on the steel surface for both acids was found to obey Temkin’s adsorption isotherm. The values of activation energy and free energy of adsorption indicated physical adsorption on mild steel surface. The potentiodynamic polarization data have shown that compounds studied are mixed type inhibitors.

To evaluate the effect of different parts of Carica papaya (leaves (LV), seeds (SD), heart wood (HW) and bark (BK)) as eco‐friendly and non‐toxic mild‐steel corrosion inhibitors in H₂SO₄ at 30 to 60 ^oC.

Acid extracts of the different parts of Carica papaya were used as inhibitors in various corrosion tests. Gravimetric and gasometric techniques were used to characterise the mechanism of inhibition.

The LV, SD, HW and BK extracts were found to inhibit mild steel corrosion in H₂SO₄. The inhibition efficiencies of the plant's part extracts follow the trend: LV > SD > HW > BK. Inhibition efficiency increased with extracts concentration but decreased with temperature. Physical adsorption of the phytochemical components of the plant on the metal surface is proposed as the mechanism of inhibition. The experimental data fits well into the Langmuir and Temkin adsorption isotherms.

The plant extracts can be used in chemical cleaning and picking processes.

The research provides information on the possible use of the different parts of Carica papaya as sources of cheap eco‐friendly and non‐toxic corrosion inhibitors.

Selected condensation products of aromatic aldehydes and thiosemicarbazide have been synthesized and evaluated as corrosion inhibitors of mild steel in 1N hydrochloric acid and 1N sulphuric acid by weight loss and potentiodynamic polarization methods. The values of activation energy and free energy of adsorption have also been determined to understand the mechanism of inhibition. The potentiodynamic polarization studies carried out at room temperature revealed that all the compounds are of mixed type inhibitors in both the acids. The adsorption of all the condensation products on the mild steel surface from both the acids has been found to obey Temkin’s adsorption isotherm. The inhibition efficiency of these compounds has been found to vary with the nature and concentration of the compounds, temperature, immersion time and nature of the acids.

Poly(styrenesulphonic acid)‐doped polyaniline has been synthesised and the influence of this polymeric compound on the inhibition of corrosion of mild steel in 1M HCl has been investigated using weight loss measurements, galvanostatic polarisation studies, electropermeation studies and a.c. impedance measurements. The polymer acts predominantly as an anodic inhibitor. Hydrogen permeation studies and a.c. impedance measurements clearly indicate a very effective performance of the compound as a corrosion inhibitor. The adsorption of the compound on the mild steel surface obeys Temkin's adsorption isotherm.

The influence of 4‐amino‐5‐mercapto‐3 n‐propyl‐1‐2‐4‐triazole (AMPT) on corrosion and hydrogen permeation through mild steel in 0.5M H₂SO₄ and 1M HCl has been studied using weight loss measurements and various electrochemical techniques. AMPT is found to be more inhibitive in H₂SO₄ than in HCl. Potentiodynamic polarisation studies clearly prove the fact that this compound behaves as a mixed inhibitor; but predominantly as a cathodic inhibitor. Hydrogen permeation studies and AC impedance measurements also indicate an improved performance of the compound in H₂SO₄. The adsorption of this compound on the mild steel surface obeys Temkin’s adsorption isotherm.

A study is carried out on the resistance to corrosion of mild steel in 5 per cent H₂SO₄ solutions at temperatures between 30 and 60°C. The effectiveness of quaternary ammonium salt used as corrosion inhibitor under the same experimental conditions was also investigated. Weight loss results and electrochemical data showed the good inhibiting action of the inhibitor, acting as anodic type. Thermodynamic parameters for adsorption of the compound are calculated using the Temkin adsorption isotherm.

The influence of thiophenol on the corrosion and hydrogen permeation 1M HCl and 0.SM H₂SO₄ has weightloss measurements, gasometric studies and other electrochemical techniques. Thiophenol inhibits the corrosion of mild steel in both the acids, but it is found to be more effective in H₂SO₄. It behaves predominantly as a cathodic inhibitor. It brings down the permeation current in both the acids, but is more effective in H₂SO₄. The adsorption of thiophenol on the mild steel surface from both the acids obeys Temkin’s adsorption isotherm.