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To study the effect of inhibition of new bipyrazole derivatives on the corrosion of steel in HCl media at various temperatures.

In this study, novel corrosion inhibitors, namely bipyrazoles were synthesised and tested as corrosion inhibitors for steel in 1 M HCl. The degree of corrosion was measured using various techniques including weight loss measurements, potentiodynamic polarisation, linear polarisation resistance (Rp) and impedance spectroscopy (EIS).

It was found that 1,5,5′‐trimethyl‐1H,2′H‐3,3′‐bipyrazole (P₁) gave the best inhibition effect. The inhibition efficiency increased with the concentration of P₁ to attain 79 per cent at 10⁻³ M. Good agreement between the various methods explored was observed. Polarisation measurements also showed that P₁ acted essentially as a cathodic inhibitor. The cathodic curves indicated that the reduction of proton at the steel surface was an activating mechanism. P₁ adsorbed on the steel surface according to Frumkin adsorption model.

The synthesis route offers the possibility of other pyrazolic compounds to be tested in the future.

The inhibitory efficiency of P₁ increased with the increase of both the concentration and the temperature (in the 298‐353 K range). As such, P₁ can be used in chemical cleaning and pickling processes.

The originality of this work is the synthesis of new inhibitors based on pyrazolic organic compounds.

The purpose of this paper is to study electrochemically and by weight loss experiments the effect of P,P′‐Bis (triphenylphosphonio) methyl benzophenone dibromide (TPPMB) on the corrosion inhibition of mild steel in 1.0M HCl solution, which will serve researchers in the field of corrosion.

Weight loss measurements were carried out on mild steel specimens in 1.0M HCl and in 1.0M HCl containing various concentrations (2×10⁻⁸M and 2×10⁻⁵M) of the laboratory synthesized TPPMB at temperatures ranging from 303 to 343 K.

TPPMB was found to be a highly efficient inhibitor for mild steel in 1.0M HCl solution, reaching about 98% at the concentration of 2×10⁻⁵M 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.

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.

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.

This paper aims to evaluate the inhibition efficiency (IE) of oxalate ions in controlling corrosion of aluminum at pH 10.

The IE has been determined by the classical weight loss method. The corrosion behavior of aluminum was investigated by using potentiodynamic polarization and electrochemical impedance measurements. Ultra violet (UV)-visible and Fluorescence spectra have been used to analyze the film formed on the aluminum surface after immersion.

The maximum IE was 88 per cent, which was offered by a mixture of 250 ppm oxalate ions and 50 ppm [Zn²⁺]. Potentiodynamic polarization data revealed that the protective film was formed on the metal surface. UV-visible and Fluorescence spectra indicated the presence of Al³⁺−oxalate complex in the protective film formed on aluminum substrate after immersion in [OX]/[Zn²⁺] solution.

The findings of this work shed more light on the corrosion inhibition of aluminum by oxalate self-assembling monolayers.

The purpose of this paper is to study the inhibition effect of (6-phenyl-3-oxopyridazin-2-yl) acetohydrazide (GP4) on the corrosion of mild steel in acidic medium by gravimetric measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS).

Weight loss measurements, potentiodynamic tests and EIS were performed during this study.

(6-phenyl-3-oxopyridazin-2-yl) acetohydrazide (GP4) was found to be a very efficient inhibitor for mild steel in 1.0 M HCl solution, reaching about 85 per cent with inhibitor concentration 1.0 × 10-3 M at 303 K.

(6-phenyl-3-oxopyridazin-2-yl) acetohydrazide (GP4) was found to play an important role in the corrosion inhibition of mild steel in acidic solution.

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

The purpose of this paper is to investigate the adsorption and corrosion inhibition of two isomeric compounds (C4H5N3) as aminopyrazine (AP) and 2-amino-pyrimidine (2AP) on mild steel (MS) in 0.5 M HCl. The study was a trial to combine experimental and modelling studies and research effect of molecular geometry on inhibition effect of inhibitor molecules.

The thermodynamic, kinetic and quantum parameters were determined. The electrochemical impedance spectroscopy and anodic polarisation measurements were obtained. The scanning electron microscope was used for monitoring electrode surface. The highest occupied molecular orbital, energy of the lowest unoccupied molecular orbital, Mulliken and natural bonding orbital charges on the backbone atoms, absolute electronegativity, absolute hardness were calculated by density functional theory (DFT)/B3LYP/6-311G (++ d,p).

Results showed that AP and 2AP suppressed the corrosion rate of MS. The corrosion current values were 0.530, 0.050 and 0.016 mA cm-2 in HCl, AP and 2AP containing HCl solutions, respectively. It was illustrated with the blocked fraction of the MS surface by adsorption of inhibitors which obeyed the Langmuir isotherm. The inhibition efficiency follows the order: 2AP > AP which is in agreement with experimental and quantum results.

This paper provides lay a bridge on the molecular geometry and inhibition efficiency by electrochemical tests and modelling study. The inhibition effect of AP and 2AP has not been compared with each other, neither experimentally nor theoretically. This study put forward possible application of 2AP as corrosion inhibitor especially for closed-circuit systems.