The effect of aqueous extract of UAE Neem (Azadirachta Indica) on the corrosion inhibition of carbon steel in 1.0 M HCl solution was investigated electrochemically, and by weight-loss experiments at temperatures ranging from 303 to 343 K. The percentage inhibition increased with the increase of the concentration of the inhibitor. At a concentration of 2.0 g/L, the percentage inhibition reached about 87% at room temperature and 80% at 303 K. The percentage inhibition decreased with the increase of temperature. The thermodynamic parameters for the adsorption of this inhibitor on the metal surface were calculated using the Temkin adsorption isotherm. The aqueous Neem leaves extract was found to be an excellent potential corrosion inhibitor because of the high content of tannin content as well as the presence of a series of complex triterpene glycosides.

The inhibition and the effect of temperature and concentration of trans-4-hydroxy-4 -stilbazole on the corrosion of mild steel in 1 M HCl solution was investigated by weight loss experiments at temperatures ranging from 303 to 343 K. The studied inhibitor concentrations were between 1×10 −7 M and 1×10 −3 M. The percentage inhibition increased with the increase of the concentration of the inhibitor. The percentage inhibition reached about 94% at the concentration of 1 × 10 −3 M and 303 K. On the other hand, the percentage inhibition decreased with the increase of temperature. Using the Temkin adsorption isotherm, the thermodynamic parameters for the adsorption of this inhibitor on the metal surface were calculated. Trans-4-hydroxy-4 -stilbazole was found to be a potential corrosion inhibitor since it contained not only nitrogen and oxygen, but also phenyl and pyridine rings that are joined together with a double bond (-C=C-) in conjugation with these rings.

PurposeTo provide a novel synthesized stilbazole derivative as a corrosion inhibitor for researchers in the field of corrosion science.Design/methodology/approachElectrochemical corrosion measurements (tafel plots) were carried out in a 3‐electrode electrochemical cell on the mild steel electrode in 1.0 M HCl and in 1.0 M HCl containing various concentrations (1.0 × 10−7 M to 1.0 × 10−3 M) of the laboratory synthesized trans‐4‐hydroxy‐4'‐stilbazole.FindingsThe percentage inhibition of trans‐4‐hydroxy‐4'‐stilbazole on mild steel in 1 M HCl solution increased with the increase of concentration of that inhibitor. This percentage inhibition steeply increased from 10.11 percent (at 1.0 × 10−7 M) to 30.34 percent at 1.0 × 10−6 M. The slope of this increase slightly decreased at the concentration of 1.0 × 10−5 M to reach 39.61 percent. At higher concentrations, the increase of the percentage inhibition was steeper than the initial part, and reached 97.92 percent at 1.0 × 10−3 M.Practical implicationsThis inhibitor could have application in industries, where hydrochloric acid solutions are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline and may render dismantling unnecessary.Originality/valueThis paper is intended to be the building block or the nucleus for a new family or group of stilbazole derivatives in electrochemical studies of corrosion inhibitors.

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Purpose -The purpose of this paper is to study electrochemically and by weight loss experiments the effect of 4-vinylbenzyl triphenyl phosphonium chloride on the corrosion inhibition of mild steel in 1.0 M HCl solution, which will serve researchers in the field of corrosion. Design/methodology/approach -Electrochemical and weight loss measurements were carried out on carbon steel specimens in 1.0 M HCl and in 1.0 M HCl containing various concentrations (1.0 £ 10 2 7 to 1.0 £ 10 2 4 M) of the laboratory synthesized 4-vinylbenzyl triphenyl phosphonium chloride at temperatures ranging from 303 to 343 K. Findings -4-vinylbenzyl triphenyl phosphonium chloride was found to be a highly efficient inhibitor for carbon steel in 1.0 M HCl solution, reaching about 99 per cent at the concentration of 1 £ 10 2 4 M at room temperature and about 96 per cent at 303 K, a concentration and temperature considered to be very moderate. The percentage of inhibition in the presence of this inhibitor was decreased with temperature which indicates that physical adsorption was the predominant inhibition mechanism because the quantity of adsorbed inhibitor decreases with increasing temperature. Practical implications -This inhibitor could have application in industries, where hydrochloric acid solutions at elevated temperatures are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary. Originality/value -This paper is intended to be added to the family of phosphonium salt corrosion inhibitors which are highly efficient and can be employed in the area of corrosion prevention and control.