42 research outputs found
Influence of halide ions on the adsorption of diphenylamine on iron in 0.5M H2SO4 solutions
Halide ions are found to enhance the inhibition performance of amines due to enhanced adsorption of amines by the adsorbed halide ions on
the metal surface. In this work, the synergistic action of halide ions on the corrosion inhibition of iron in 0.5M H2SO4 by diphenylamine has
been found out by electrochemical impedance and polarization methods. Analysis of impedance data has been made with equivalent circuit with
constant phase angle element for calculation of double layer capacitance values. Experiments have been carried out in the concentration range of
100–1000 ppm of diphenylamine in the presence of 0.5–1.0×10−3M of halide ions. Diphenylamine is found to be a cathodic inhibitor and the
inhibition efficiency of about 65% is obtained at 1000 ppm. The anodic and cathodic Tafel slopes in the presence of diphenylamine alone and with
halide ions are 65±5 and 105±5mV, respectively. Diphenylamine inhibits corrosion by adsorption and the surface coverage values are increased
considerably in the presence of halide ions. In the presence of iodide ions, the inhibition efficiency of diphenylamine at 100 ppm is increased to
more than 90%. In the case of other halide ions, the inhibition efficiency of diphenylamine in increased to 80% at 1000 ppm. The order of synergism
of halide ions is I−�Br− >Cl−. The highest synergistic effect of iodide ions is due to chemisorption with metal surface due to its larger size and
ease of polarizability
Effect of cerium ions on corrosion inhibition of PANI for iron in 0.5 M H2SO4
In recent years conducting polymers such as polyaniline are used as corrosion inhibitors for metals in acids. The performance of the inhibitor
can be enhanced either by the addition of halide ions or metal cations. A study has been made on the effect of addition of ceric ions on the corrosion
inhibition performance of polyaniline for iron in 0.5 M H2SO4. Techniques such as electrochemical impedance spectroscopy, potentiodynamic
polarization and linear polarization resistance methods have been employed to study the corrosion inhibition. The polyaniline has been used in the
concentration range of 10–100 ppm and the ceric ions concentration has been maintained at 1 � 10�3 M. The inhibition efficiency of polyaniline at
10 ppm has been increased from 53 to 88% and for 50 ppm from 71 to 90% in the presence of ceric ions. The enhanced inhibition of polyaniline in
presence of ceric ions is due to the higher coverage of polyaniline–cerium complex
Co-adsorption effect of polyaniline and halide ions on the corrosion of iron in 0.5 M H2SO4 solutions
The synergistic effect of halide ions on the inhibition of corrosion of iron in 0.5 M H2SO4 solutions by polyaniline has been studied
by polarization and impedance methods. Addition of 0.5 · 103M I ions enhanced the inhibition efficiency of polyaniline at
10 ppm from 53% to 90%. However in the case of bromide and chloride ions, the inhibition efficiency of polyaniline at 50 ppm has
been increased from 71% to 90%. The synergism parameter in all cases is found to be greater than 1. The synergistic effect is attributed
to enhanced adsorption of polyaniline by the adsorbed halide ions
Influence of metal cations on the inhibitive effect of polyaniline for iron in 0.5 M H2SO4
Polyaniline and metal cations such as Zn2+ and Mn2+ ions have been found to inhibit corrosion of iron in sulphuric acid moderately. It has been reported that the metal cations are found to interact directly with polyaniline via protonation of imine nitrogen atom of quinoid groups of polyaniline and induce chemical and confirmational changes to polymer. Hence a study has been made on the inhibition of iron in 0.5 M H2So4 by polyaniline in the presence of Zn2+ and Mn2+ ions (1 * 10pow-3 M) by electrochemical impedance spectroscopy, linear polarization and tafel polarization methods. The inhibition efficiencies of polyaniline are found to be 40% for 10 ppm and 72% for 100 ppm. But in the presence of metal cations, the inhibition efficiencies of polyaniline are found to be increased to 80% for 10 ppm and more than 90% for 100 ppm. Higher inhibition efficiency of polyaniline in the presence of metal cation is attributed to the increased electron rich benzenoid groups absorb more effectively on iron surface and there by reduces the corrosion rate markedl
Corrosion Inhibition of Iron in 0.5 mol L-1 H2SO4 by Halide Ions
O efeito de inibição de Ãons haletos, tais como iodeto, brometo e cloreto, na corrosão de ferro em
solução 0,5 mol L-1 de H2SO4, e o comportamento da adsorção desses Ãons na superfÃcie do eletrodo,
foram estudados pelos métodos de polarização e de impedância. Foi observada uma inibição de
aproximadamente 90% para Ãons iodeto a 2,5 × 10-3 mol L-1 e para Ãons brometo a 10 × 10-3 mol L-1, e de
80% para Ãons cloreto a 2,5 × 10-3 mol L-1. O efeito da inibição aumenta com o aumento da concentração
dos Ãons haletos I– e Br–, mas decresce no caso do Cl–, para concentrações maiores que
5 ×10-3 mol L-1. Os valores de capacitância de dupla camada diminuÃram consideravelmente na presença
dos Ãons haletos, o que indicou que esses ânions são adsorvidos no ferro no potencial de corrosão.
The inhibition effect of halide ions such as iodide, bromide and chloride ions on the corrosion of
iron in 0.5 mol L-1 H2SO4 and the adsorption behaviour of these ions on the electrode surface have
been studied by polarization and impedance methods. It has been found that the inhibition of nearly
90% has been observed for iodide ions at 2.5 × 10-3 mol L-1, for bromide ions at 10 × 10-3 mol L-1 and
80% for chloride ions at 2.5 × 10-3 mol L-1. The inhibition effect is increased with increase of halide
ions concentration in the case of I– and Br– ions, whereas it has decreased in the case of Cl– ion at
concentrations higher than 5 × 10-3 mol L-1. The double layer capacitance values have decreased
considerably in the presence of halide ions which indicate that these anions are adsorbed on iron at
the corrosion potential
Investigation of the inhibitive effect of poly(diphenylamine) on corrosion of iron in 0.5 M H2SO4 solutions
In recent years, polymer amines such as polyaniline has been reported as an efficient corrosion inhibitor for iron in acid media. In this
paper, the performance of poly(diphenylamine) as corrosion inhibitor for iron in 0.5 M H2SO4 has been evaluated by potentiodynamic
polarization, linear polarization and electrochemical impedance spectroscopy and compared with the performance of the diphenylamine
monomer. It has been found that poly(diphenylamine) is an efficient inhibitor since the maximum efficiency of 96% has been observed at
very low concentration of 10 ppm where as the monomer has given an efficiency of 75% at 1000 ppm. Besides, poly(diphenylamine) has
been found to improve the passivation characteristics of iron in 0.5 M H2SO4. FTIR studies have shown that the poly(diphenylamine) is
strongly adsorbed on the iron surface and inhibits the corrosion effectively
Inhibition of iron corrosion in 0.5 M sulphuric acid by metal cations
Corrosion inhibitors are widely used in acid solutions during pickling and descaling. Mostly organic compounds containing N, O, and S groups
are employed as inhibitors. In this study, the inhibition performance of metal cations such as Zn2+, Mn2+ and Ce4+ ions in the concentration range
1–10 � 10�3 M has been found out. The corrosion behaviour of iron in 0.5 M H2SO4 in the presence of metal cations is studied using polarization
and impedance methods. It is found that the addition of these metal cations inhibits the corrosion markedly. The inhibition effect is in the following
order Ce4+ � Mn2+ > Zn2+