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Adsorption rate and protective effect of tributyl(cyclohexyl)ammonium chloride inhibitor on the acidic corrosion of steel
Author(s) -
Magerramov A. M.,
Rzayev Z. M. O.,
Aliyev I. A.,
Khalilova F. I.
Publication year - 2010
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.200905462
Subject(s) - adsorption , chemistry , ammonium chloride , corrosion , chloride , gravimetric analysis , inorganic chemistry , electrochemistry , metal , ammonium , corrosion inhibitor , polarization (electrochemistry) , electrode potential , electrode , nuclear chemistry , organic chemistry
The inhibition of corrosion of a steel surface by an inhibitor, tributyl(cyclohexyl)ammonium chloride (TBCA), was investigated by gravimetric and electrochemical polarization measurements in various aqueous solutions of HCl and H 2 SO 4 acids. It is known that the most extensive corrosive destruction proceeds during the initial stage of contact between the metallic surface and the aggressive surroundings. The change from H 2 SO 4 to HCl considerably decreases the time for formation of an adsorption layer. The high adsorption of the surface‐active cationic TBCA on the steel electrode surface can be explained by the specific adsorption of Cl − anions increasing the negative charge on the electrode surface. It was observed that the value of the polarizing current can be increased from time to time by addition of more TBCA inhibitor. This fact can be explained by the low stability of the film‐forming layer on the steel. A similar decrease of the protective effect was also observed in HCl solution. The inhibitor provides at least a slowing of the corrosion process ( τ = 21 min). It was found that an increase in H 2 SO 4 concentration from 1.0 to 0.2 N did not change the protective action of the inhibitor and had rather high values ( θ = 283 ma/h, ψ = 84%, and τ = 14 min at [I] = 3.5 × 10 −4 mol/L). It was shown that the attraction constant has a negative value ( A = −1.5 and K a = 22.3) for the inhibitor, which relates to a high value for the adsorption ability of TBCA in HCl solution and therefore with the intermolecular repulsive force between adsorption molecules having similar charges. The protective action of TBCA increases with an increase in temperature, which is correlated with the chemical nature of its adsorption on the steel surface.