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To evaluate the effect of natural rosemary oil as non toxic inhibitor on the corrosion of steel in H₃PO₄ media at various temperatures.

The oil was hydro‐distilled. The oil was used as inhibitor in various corrosion tests. Gravimetric and electrochemical techniques were used to characterise the corrosion mechanism.

Chromatographic analysis by GC showed that the oil was rich in 1,8‐cineole. The oil was a good inhibitor. But, its efficiency decreased with temperature.

The inhibition efficiency increased with the concentration of the natural oil to attain 73 per cent at 10 g/l. Good agreement between the various methods explored was observed. Polarisation measurements showed that rosemary oil acted essentially as a cathodic inhibitor.

The efficiency of the oil increased with the concentration but decreased with the rise of temperature in the 298‐348 K range. The natural oil could thus be used in chemical cleaning and pickling processes.

The originality of this work is the finding of a safe and cheap inhibitor from natural plants.

The inhibition of the copper corrosion in aerated 3 per cent sodium chloride solution was studied by using electrochemical polarisation, weight loss and impedance measurements in the presence of different concentration of synthesised bipyrazolic compounds: N,N‐bis (3,5‐dimethylpyrazol‐1‐ylmethyl) butylamine (bipy1); N,N‐bis (3,5‐dimethylpyrazol‐1‐ylmethyl) allylamine (bipy2); N,N‐bis (3,5‐dimethylpyrazol‐1‐ylmethyl) ethanolamine. (bipy3); N,N‐bis (3,5‐dimethylpyrazol‐1‐ylmethyl) cyclohexylamine (bipy4); N,N‐bis (3‐carbomethoxy‐5‐methylpyrazol‐1‐ylmethyl) cyclohexylamine (bipy5); N,N‐bis(3‐carboethoxy‐5‐methylpyrazol‐1‐ylmethyl) cyclohexylamine (bipy6). The inhibition efficiencies obtained from cathodic Tafel plots, polarisation resistance and weight loss are in good agreement with electrochemical impedance spectroscopy (EIS) measurements. All these additives were found to be excellent inhibitors of copper corrosion. The difference in inhibition efficiencies of these inhibitors was not big, but the optimum concentration for maximum efficiency was slightly dependent on the substitution of each molecule. The studied molecules act as mixed‐type inhibitors. Detailed study of bipy1 shows that the maximum inhibition efficiency revolves around 99 per cent from 5×10⁻⁴ M of inhibitor. This latter adsorbs on the copper surface according to the Frumkin isotherm model. The inhibition efficiency of bipy1 decreases with the rise of temperature in the range 25 – 60°C.

This paper aims to study the inhibition effect of 2-pyridinealdazine on the corrosion of mild steel in an acidic medium. The inhibition effect was studied using weight loss, electrochemical impedance spectroscopy, and Tafel polarization measurements.

Weight loss measurements, potentiodynamic tests, electrochemical impedance spectroscopy, X-ray diffraction and spectral and conformational isomers analysis of A (E-PAA) and B (Z-PAA) were performed were investigated.

2-pyridinealdazine (PAA) acts as a good inhibitor for the corrosion of steel in 2.0 M H₃PO₄. The inhibition efficiency increases with an increase in inhibitor concentration but decreases with an increase in temperature.

This paper is intended to be added to the family of azines which are highly efficient inhibitors and can be used in the area of corrosion prevention and control.

This paper seeks to evaluate the effect of natural menthols and their synthesised epoxy‐allylmenthols as a non‐toxic inhibitor on the corrosion of steel in HCl media at various temperatures.

Epoxy‐allylmenthols were synthesised and characterised. Gravimetric technique was used to measure the efficiency of corrosion inhibition.

Modified allylmenthol (to epoxy‐allylmenthol) exhibited a good inhibition. But its efficiency decreases with temperature.

The inhibition efficiency increases with the concentration of inhibitor to attain 74 percent at 0.8 g/l.

The efficiency of menthol derivatives increases with the concentration but decreases with rise of temperature in the 303‐328 K range. Natural inhibitor can be used in chemical cleaning and pickling processes.

The originality of this work is to find a safe and cheap eco‐friendly inhibitor from natural plants.

The inhibition of the corrosion of the mild steel in 1M HCl by new bipyrazolic compounds has been studied by weight loss, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. Results obtained reveal that these compounds are very good inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration and reached 94 at 10^–3M for the bipyrazoles studied. Potentiodynamic polarisation studies clearly reveal that the presence of the bipyrazoles does not change the mechanism of the hydrogen evolution reaction and they act essentially as cathodic inhibitors. The effect of temperature on the corrosion behaviour of mild steel in 1M HCl without and with the bipyrazoles at 10^–3M was studied in the temperature range from 298° to 343°K. EIS measurements show the increase of the transfer resistance with the inhibitor concentration.

The effects of the addition of poly(4‐vinylpyridine) (P4VP) and its derivative poly(4‐vinylpyridine poly‐3‐oxide ethylene) (P4VPPOE) on the corrosion of Cu60‐Zn40 in 0.5M HNO₃ have been investigated by potentiodynamic and weight loss measurements. Both of the studied polymers decrease the corrosion rate. Their inhibition efficiency (E%) increases with the concentration. The maximum of inhibition was obtained for P4VPPOE (100 per cent at 10^–5M). E% obtained from cathodic Tafel plots and weight loss methods were in good agreement. The inhibitors were adsorbed on the Cu60‐Zn40 surface according to the Frumkin adsorption isotherm model. P4VPPOE acts as a cathodic inhibitor and its efficiency is temperature independent.

The effects of natural Artemisia oil on the corrosion of steel in molar hydrochloric acid were studied by the measurements of weight loss, electrochemical and EIS polarisation. The results obtained revealed that Artemisia oil reduced the rate of corrosion. The corrosion inhibition efficiency increased with the increase of inhibitor concentration. Potentiodynamic polarisation studies clearly revealed that the presence of the natural Artemisia oil did not alter the mechanism of the hydrogen evolution reaction and acted essentially as a cathodic inhibitor. Good agreement between gravimetric and electrochemical polarisation results was noted. The effect of temperature on the corrosion behaviour of steel in 1M HCl, with and without the oil in the temperature range of 308‐353 K, indicated that inhibition efficiency increased with temperature. The adsorption of Artemisia oil on the steel is followed by Frumkin adsorption isotherm.

To evaluate the effect of some tetrazole compounds as corrosion inhibitors of copper in HNO₃ at various temperatures.

1‐phenyl‐5‐mercapto‐1,2,3,4‐tetrazole (PMT) was selected as the best inhibitor among the tetrazole compounds tested. Gravimetric and electrochemical techniques were conducted.

PMT was an excellent inhibitor for copper in acid. Its efficiency attained 97.5 per cent and decreased slightly with temperature.

The inhibition efficiency increased with the concentration of PMT to reach 97.5 per cent at 10⁻³ M. Good agreement between the various methods explored was observed. Polarisation measurements also showed that PMT acted as a mixed inhibitor.

The efficiency of PMT increased with the concentration but decreased with rise of temperature in the 298‐333 K range. As such, PMT could be used in chemical cleaning and pickling processes.

The originality of this work was the finding of an efficient inhibitor (PMT) having a nearly 100 per cent efficiency.

The purpose of this paper is to make people aware of organic corrosion inhibitors.

As it is a literature review paper, no specific method is used.

It has been found that plant extracts and oils show inhibition efficiency up to 98 percent, so it is certain that plant extracts and oils are effective corrosion inhibitors and can be successfully used at the industrial level.

Plant extracts and oils are also found to be non‐toxic, highly efficient, renewable and cheap. But less effort has been given towards the identification of which compound is active in the extract.

The paper shows detailed account of the inhibitors obtained from plants, which are used as natural corrosion inhibitors.

To evaluate the effect of synthesised calixarenes as new inhibitors on the corrosion of steel in HCl media at various temperatures.

Calixarenes have been synthesised and tested as corrosion inhibitors. Gravimetric technique and potentiodynamic polarisation and impedance spectroscopy methods were used.

Calixarenes exhibited a good inhibition. Their efficiency decreases slightly with temperature.

It was found that the inhibition efficiency increases with the concentration of inhibitors to reach 92 per cent at 10⁻⁴M.

The efficiency of calixarene derivatives increases with the concentration and falls slowly with temperature to attain 84 per cent at 353 K range. Calixarenes can be used in chemical cleaning and pickling processes.

The originality of this work is to find an inhibitor to give protection close to 100 per cent.