S. S. Abd El-Rehim

4-Aminoantipyrine as an inhibitor of mild steel corrosion in HCl solution

Abstract4-aminoantipyrine (AAP) was tested as a corrosion inhibitor for mild steel in 2 M HCl solution using different techniques: weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that AAP is an inhibitor for mild steel in this medium. The inhibition was assumed to occur via adsorption of the inhibitor molecule on the metal surface. In the 20 to 60 ∘C temperature range, the AAP adsorption follows the Flory–Huggins isotherm and/or the El-Awady et al. kinetic-thermodynamic model. The protection efficiency increases with increasing inhibitor concentration (in the range 10−310−2 M) but decreases with increasing temperature. The thermodynamic functions of dissolution and adsorption processes were calculated.

Corrosion Inhibition of Mild Steel in Acidic Medium using 2-amino Thiophenoland 2-Cyanomethyl Benzothiazole

The corrosion inhibition characteristics of 2-amino thiophenol (ATP) and 2-cyanomethyl benzothiazole (CNMBT) on two types of steel in 1m HCl medium were investigated at different temperatures (25, 30, 35, 40 and 50°C). The pitting corrosion behaviour for the same system was studied using a potentiodynamic technique. The pitting corrosion resistance of steel samples increased with increase in concentration of the ATP and CNMBT. Some samples were examined by scanning electron microscopy. The effects of the inhibitors on the general corrosion of the two samples were investigated by using gravimetric and galvanostatic polarization techniques. The inhibition efficiencies increased with increase their concentration but decreased with increase in temperature. Free energies of activation, enthalpies and entropies for the inhibition processes were determined from rate constant data measured and different temperatures at different concentrations of ATP and CNMBT. Results were compared with fits obtained from the application of the Langmuir isotherm. Results were correlated to the chemical structure of the inhibitors. The inhibition efficiency of CNMBT is higher than that of ATP.

Inhibition of chloride localized corrosion of mild steel by PO43-, CrO42-, MoO42-, and NO2- anions

The effect of phosphate (PO43−), chromate (CrO42−), molybedate (MoO42−) and nitrite (NO2−) ions on the pitting corrosion of steel in 0.1 M NaCl solution has been studied using potentiodynamic polarization and SEM techniques. The addition of increasing concentrations of PO43−, CrO42−, MoO42− and NO2− anions causes a shift of the pitting potential (Epit) in the positive direction, indicating the inhibitive effect of the added anions on the pitting attack. The adsorption characteristics of these anions on the steel surface play a significant role in the inhibition processes. The PO43−anion has a strong inhibitive effect of chloride pitting corrosion. The effect of different inorganic anions on the pitting corrosion of steel samples I and II (with different composition) was also studied in 0.1 M NaCl solution.

Electrodeposition of cobalt-nickel alloys from Watts-type baths

The electrodeposition of cobalt-nickel alloys was carried out from Watts-type baths of composition 5–60gl−1 CoSO4 · 7H2O, 100–300gl−1 NiCl2 · 6H2O and 25gl−1 H3BO3 at a pH of 4.4. The cathodic polarization during electrodeposition and the alloy composition were greatly influenced by the concentrations of the depositable metal ions; whereas, the cathodic efficiency was only slightly affected. Under the examined conditions, the electrodeposition of the alloys belonged to the anomalous type. X-ray diffraction studies revealed that the alloys were deposited in the face-centred cubic structure and consisted of a mixture of the two phases α(Co) andβ(Ni). Sound, smooth and bright alloy deposits were obtained and their properties were improved by increasing the nickel content of the bath.

Electroplating of a Co-Cu alloy from a citrate bath containing boric acid

The effects of bath composition, current density and temperature on cathodic polarization, cathodic current efficiency of codeposition, composition and structure of Co–Cu alloys electroplated on a steel substrate from citrate baths have been studied. Addition of boric acid to citrate electrolyte increases the percentage of Co in the deposits and improves the quality of these deposits. The cathodic current efficiency of the baths is relatively high and increases with increases in the metal content in the bath and the current density but decreases with temperature. The composition of the deposit is controlled by the applied current density. At low current densities, Cu-rich alloys were obtained. At higher current densities, the composition of the alloys was controlled by the limiting current density of Cu codeposition. The Co content of the deposits increases with increases in the metal content in the bath and the temperature. The structure of the deposited alloys was characterized by anodic stripping and X-ray diffraction techniques. The deposited alloys consisted of a single solid solution phase with a face-centred cubic structure. © 2000 Society of Chemical Industry

Electropolymerization of o-Aminobenzoic Acid and Characterization of the Obtained Polymer Films

ABSTRACT Poly(ortho-aminobenzoic acid), as a ring substituted derivative of aniline, has been synthesized electrochemically from acid medium on platinum electrode. The reaction parameters such as current density, hydrochloric acid concentration, monomer concentration, temperature, and reaction duration time were investigated. The kinetic study shows that the orders of polymerization reaction are 1.01, 1.33, and 0.41 with respect to hydrochloric acid concentration, monomer concentration, and current density, respectively. The apparent activation energy (Ea) is found to be 134.8 kJ mol−1. The polymer films obtained have been characterized by cyclic voltammetry, X-ray diffraction, elemental analysis, thermogravimetric analysis, scanning electron microscopy, 1H-NMR, and IR spectroscopy. The mechanism of the electrochemical polymerization reaction has been discussed.

Electrochemical Polymerization of 2-Amino-4-(4-methoxyphenyl)thiazole and Characterization of the Obtained Polymer

ABSTRACT Electrochemical oxidative polymerization of 2-amino-4-(4-methoxyphenyl)thiazole on platinum electrode in hydrochloric acid medium was carried out. Different reaction parameters were investigated such as current density, acid concentration, monomer concentration, and temperature with duration of time. The orders of the electropolymerization reaction were found to be 1.10, 1.10, and 0.99 with respect to current density, HCl acid, and monomer concentrations, respectively. The apparent activation energy (Ea) was found to be 66.91 KJ mol−1. The obtained polymer films are characterized by IR, UV, 1H-NMR, elemental analysis, and cyclic voltammetry. The mechanism of the electropolymerization reaction has also been discussed.

Electrochemical Polymerization of 3-Methoxyaniline and Characterization of the Obtained Polymer

ABSTRACT Electropolymerization of 3-methoxyaniline on platinum electrode in acid medium was carried out under different reaction conditions such as temperature, current density, hydrochloric acid, and monomer concentrations with duration time. The initial rate of the electropolymerization reaction is small and the orders are found to be 0.99, 0.98, and 0.97 with respect to current density, acid, and monomer concentrations, respectively. The apparent activation energy (Ea) is found to be 59.673 KJ mol−1. The rate law is RP = K2[D]0.99 [HCl]0.98 [M]0.97. The obtained polymer films were characterized by 1H-NMR, elemental analysis, IR, and cyclic voltammetry. The mechanism of the electropolymerization reaction has also been discussed. The thermogravimetric analysis (TGA) was used to confirm the proposed structure and determination of the number of water molecules in the polymeric chain unit. X-ray and scanning electron microscopic analysis were used to investigate the surface morphology.

Electrochemical Polymerization of 2-Chloroaniline and Characterization of the Obtained Polymer Films

ABSTRACT Electrochemical polymerization of 2-chloroaniline on platinum electrode in acid medium was carried out under various reaction conditions, altering temperature, current density, hydrochloric acid, and monomer concentrations and time duration. The initial rate of the electropolymerization reaction is small and the orders are found to be 1.00, 1.06, and 0.96 with respect to current density, acid, and monomer concentrations, respectively. The apparent activation energy (Ea) is found to be 44.336 kJ mol−1. The rate law is RP = K 2[D]1.00[HCl]1.06[M]0.96. The obtained polymer films are characterized by 1H-NMR, elemental analysis, IR, and cyclic voltammetry. The mechanism of the electropolymerization reaction is also discussed. The thermogravimetric analysis (TGA) is used to confirm the proposed structure and determination of the number of water molecules in the polymeric chain unit. X-ray and scanning electron microscopic analysis are used to investigate the surface morphology.

Electrocopolymerization of a Binary Mixture of 2-chloroaniline and 2 -amino -4 -(4 -methoxyphenyl) thiazole

Electropolymerization of a binary mixture of 2-chloroaniline and 2-amino-4-(4-methoxyphenyl) thiazole on platinum electrode in acid medium was carried out under varying reaction conditions as temperature, current density, hydrochloric acid, and monomer concentrations with duration time. The initial rate of the electrocopolymerization reaction was small and the rate law was RP = K2[D]0.92[HCl]0.98[M]1.93. The apparent activation energy (Ea) was found to be 57.34 kJ mol−1. The obtained copolymer films were characterized by 1HNMR, elemental analysis, GPC, IR, UV-visible, and cyclic voltammetry compared with those of the two homopolymers. The mechanism of the electrocopolymerization reaction had been also discussed. The monomer reactivity ratio (r1 and r2) was calculated. The thermogravimetric analysis (TGA) was used to confirm the proposed structure and determination of the number of water molecules in the copolymeric chain unit. X-ray and scanning electron microscopic analysis were used to investigate the surface morphology.