AC Impedance Studies on Relationship between Adsorption Behavior of Polar Organic Compounds on Anodically Polarized Nickel and the HSAB Principle

Aramaki, Kunitsugu; Nishihara, Hiroshi

doi:10.1149/1.2100616

Cited by 43 publications

(23 citation statements)

References 23 publications

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“…[3][4][5]39,[48][49][50][51] Basically, two types of correlations are consid- 48,49 where B is the adsorption-desorption equilibrium constant, X i denotes a quantum molecular index, A i denotes the regression coefficient and C is a constant. The latter equation appears to be more theoretically justified as it implies proportionality of the fundamental thermodynamic quantities that pertain to the inhibitor adsorption, ⌬H ads , ⌬G ads and ⌬S ads , to the linear combination of quantum indexes.…”

Section: C674mentioning

confidence: 99%

“…The equality = IE/100 is assumed in many articles. 5,6 It is worth stressing at this point that only in the case of pure geometric blocking of the electrode surface by the inhibitor, the efficiency, IE, can be treated as equivalent to the surface coverage, . 52 The Langmuir isotherm may itself be a crude approximation as the metal surface inhomogeneity and the interaction between the adsorbed molecules are neglected.…”

Section: C674mentioning

confidence: 99%

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Adsorption of Organic Anions on Low-Carbon Steel in Saturated Ca(OH)[sub 2] and the HSAB Principle

Martinez¹,

Valek²,

Stipanović

2007

J. Electrochem. Soc.

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This paper represents a fundamental study of corrosion inhibition behavior of selected organic anions on low-carbon steel in saturated Ca͑OH͒ 2 solution containing chlorides. The compounds studied include eight amino acids, two carboxylic acids, ascorbic acid and a mimosa tannin extract. All the inhibitors suppressed the reduction of O 2 , a process that is known to be strongly catalyzed on passive iron, the essential step being O 2 reaction with Fe͑II͒ surface sites. The proposed mechanism of inhibition involves formation of surface chelates which tend to stabilize iron in Fe͑III͒ state and increase the Tafel slope of the actual potential dependence of the ͓Fe͑II͔͒ surface centers. In accordance with the hard and soft acid and base principle, the corrosion inhibition effect was well correlated with the absolute electronegativity of the anions obtained from the semiempirical quantum molecular modeling calculations. The lack of correlation of the inhibition effect with the absolute hardness of the inhibitor anions has been explained by considering the charge of the anions as the companion parameter for absolute hardness. The highest degree of inhibition was observed for ascorbic acid that also showed a clearly pronounced increase in the pitting initiation potential.The overwhelming majority of literature on corrosion inhibitors deals with the effect of inhibitors on uniform corrosion, e.g., of steel in acidic or neutral solutions while the inhibitors for pitting corrosion are far less studied. 1,2 Since the adsorption of an aggressive anion on the film surface is associated with the breakdown of a passive film, cation inhibitors may suppress pitting corrosion via electrostatic interaction with the aggressive anion. 3 On the other hand, the action of the anion corrosion inhibitors for bare or oxidecovered metal surfaces can be interpreted in terms of the hard and soft acid and base ͑HSAB͒ principle. 4-6 In a corrosion system containing the aggressive anions and the inhibitor anions, oxidized metal acts as a hard Lewis acid and anions act as Lewis bases. Hence, the inhibitor anions should be harder bases than the aggressive anions, since they must preferentially bind to the highly oxidized metal ions on the film surface via replacement of oxide or hydroxide groups.In particular, compounds containing carboxylic group have been reported to be effective inhibitors of passive film breakdown with chloride on the surface of various metals and alloys by means of their competitive adsorption on the oxide film, since the carboxylate ions are harder bases than chloride. 7 The aim of the present work is to assess the adsorption behavior of eight amino acids ͑proline, PRO; cystine, CYS-SS-CYS; arginine, ARG; phenylalanine, PHE; tryptophane, TRP; tyrosine, TYR; alanine, ALA; and glutamic acid, GLU͒ and two carboxylic acids ͑ox-alic, OXA and tartaric, TAR͒ on steel in sat. Ca͑OH͒ 2 solution in the presence of chloride ions. Ascorbic acid ͑AA͒ and mimosa tannin ͑MT͒ have been investigated also for comparative purposes as some prev...

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Section: C674mentioning

confidence: 99%

Section: C674mentioning

confidence: 99%

Adsorption of Organic Anions on Low-Carbon Steel in Saturated Ca(OH)[sub 2] and the HSAB Principle

Martinez¹,

Valek²,

Stipanović

2007

J. Electrochem. Soc.

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“…The hard acids prefer to bind to hard bases forming a stable complex bond under the influence of electric interactions. The adsorption ability of anions is closely related to the HSAB principle [32]. The low coordination ability of the perchlorate ion, however, will tend to make it the least susceptible to adso~tion and hence the least capable to modi~ or affect the corrosion characteristics of a given metal.…”

Section: Resultsmentioning

confidence: 99%

Studies on the Kinetics of Aluminium Metal Dissolution in Aggressive Acid Media Containing Inorganic Anions

Aziz¹,

El-Awady²,

Abd-El-Nabey³

1997

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The kinetics of chloride ion pitting and inorganic anions inhibition of aluminium metal corrosion in 1.0M solutions of perchloric acid were studied at 30"C in the ranges 0 ~ Cl-~ 0.8 mol L-1; 0 ~ NO-; ~ 0.18 mol L-1 and'O ~ ST ~ 1,0 mol L-1, where ST represents the sum of sol-and HSO~ species all at an ionic strength I = 2.0. NaC104-The reactions were found to be governed by multistep equilibria in which Cl-, NO ~. HSO;, soland dissolved oxygen 02 (g) compete for the metal surface. The rate of coltosion was found to be zero-order overall with an observed rate constant dependence on CI-of the form: kK K [Cl-f (k-k) = 2 3 obs 0 K [0 ]+K [Cl-]+K K [Cl-f 1 2 2 2 3 where Kl is the equilibria constant for °2(g) adsorption and K2 & K3 are successive adsorption constants for Cl-ions. The addition of nitrate or sulfate ions resulted in the inhibition of aluminium corrosion. The results are discussed in tern\s of multistep competitive equilibria in which the nitrate or the sulfur containing species (SO~-, HS04) screen the metal surface from chloride attack. In all cases a mechanism involving three competitive equilibria viz. molecular oxygen adsorption, Cl-adsorption and inhibitor adsorption followed by a rate determining dissolution step is proposed for the reactions.

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“…where p'0 is a measure of the metal softness as an acid and ~'0 a constant (6,7). Assuming the Langmuir adsorption, the coverage values of the inhibitor and CI-, 01L and 02 L, are given by…”

Section: Discussionmentioning

confidence: 99%

Effect of Chloride Ion on the Relationship Between the Adsorption of Polar Organic Compounds on Nickel or Iron and the HSAB Principle

Aramaki¹,

Mochizuki²,

Nishihara³

1988

J. Electrochem. Soc.

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The hard and soft acids and bases principle (HSAB principle) was confirmed as being applicable to the adsorption behavior and corrosion inhibition effect of polar organic compounds on nickel and iron in HC104-HC1 solutions. Surface coverage of the compounds was calculated on the basis of the Frumkin adsorption. Since the softness of metal surface increased in the presence of CI-, the compound classified as a soft base was readily adsorbed on the surface where C1-was adsorbed. A polar organic compound, R.X:, acting as a corrosion inhibitor, is chemisorbed on a metal, M, by forming a charge transfer bond, as R~X: + M ~ R~X:M ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.117.10.200 Downloaded on 2015-03-16 to IP

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AC Impedance Studies on Relationship between Adsorption Behavior of Polar Organic Compounds on Anodically Polarized Nickel and the HSAB Principle

Cited by 43 publications

References 23 publications

Adsorption of Organic Anions on Low-Carbon Steel in Saturated Ca(OH)[sub 2] and the HSAB Principle

Adsorption of Organic Anions on Low-Carbon Steel in Saturated Ca(OH)[sub 2] and the HSAB Principle

Studies on the Kinetics of Aluminium Metal Dissolution in Aggressive Acid Media Containing Inorganic Anions

Effect of Chloride Ion on the Relationship Between the Adsorption of Polar Organic Compounds on Nickel or Iron and the HSAB Principle

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