S. Rajendra, B.V. Apparao and N. Palaniswamy
The synergistic effect of sodium salt of 2‐chloroethyl phosphonic acid (2‐Cl EPA) and Zn2+, in controlling corrosion of carbon steel in a neutral aqueous environment containing…
Abstract
The synergistic effect of sodium salt of 2‐chloroethyl phosphonic acid (2‐Cl EPA) and Zn2+, in controlling corrosion of carbon steel in a neutral aqueous environment containing 60ppm Cl–, was evaluated by weight‐loss and electrochemical methods. A formulation consisting of 300ppm 2‐Cl EPA and 300ppm Zn2+ was observed to deliver 95 percent inhibition efficiency. A suitable mechanism of corrosion inhibition has been proposed which is based on the results obtained from polarization study and uv‐visible absorption and reflectance spectra. 2‐Cl EPA‐Zn2+ system appears to function as a mixed inhibitor. The protective film consisted of Fe2+ ‐2‐Cl EPA complex, Zn(OH)2 and oxides of iron. The film was found to be semiconducting in nature.
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S. Rajendran, B.V. Apparao and N. Palaniswamy
The inhibition efficiencies of ethyl phosphonic acid (EPA) and 2‐chloroethyl phosphonic acid (2‐Cl EPA) in the presence of Zn2+, in controlling the corrosion of mild steel in a…
Abstract
The inhibition efficiencies of ethyl phosphonic acid (EPA) and 2‐chloroethyl phosphonic acid (2‐Cl EPA) in the presence of Zn2+, in controlling the corrosion of mild steel in a neutral aqueous environment containing 60ppm Cl‐ have been evaluated by weight‐loss method and compared. It is observed that 2‐Cl EPA‐Zn2+ system has more inhibition efficiency than an EPA‐Zn2+ system. It is due to the electron withdrawing power of the Cl atom and its size. The nature of the protective film formed on the surface of the metal has been analysed by X‐ray diffraction, uv‐visible reflectance and luminescence spectra.
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Susai Rajendran, B.V. Apparao and N. Palaniswamy
The formulation consisting of 50ppm polyacrylamide (PAA), 300ppm phenyl phosphonic acid (PPA) and 50ppm Zn2+ has 95 per cent inhibition efficiency in controlling corrosion of mild…
Abstract
The formulation consisting of 50ppm polyacrylamide (PAA), 300ppm phenyl phosphonic acid (PPA) and 50ppm Zn2+ has 95 per cent inhibition efficiency in controlling corrosion of mild steel in a neutral aqueous environment, containing 60ppm Cl—, a situation commonly encountered in cooling water systems. A discussion of mechanistic aspects of corrosion inhibition is based on the results obtained from a potentiostatic polarization study, UV‐visible, FTIR and luminescence spectra. The protective film is found to be luminescent and to consist of Fe2+‐PAA complex, Fe2+‐PPA complex and Zn(OH)2.
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S. Rajendran, B.V. Apparao and N. Palaniswamy
The inhibition efficiency of the HEDP‐Zn2+ system, in a wider concentration range of Zn2+ and HEDP (10, 50, 100, 150, 200 and 300ppm), in controlling corrosion of mild steel…
Abstract
The inhibition efficiency of the HEDP‐Zn2+ system, in a wider concentration range of Zn2+ and HEDP (10, 50, 100, 150, 200 and 300ppm), in controlling corrosion of mild steel immersed in low chloride medium (Cl‐ = 60ppm) has been evaluated by weight‐loss study. Synergism parameters have been calculated between HEDP and Zn2+. The plot of C/θ vs. C gives a straight line. The HEDP‐Zn2+ system functions as a mixed inhibitor. The protective film has been analysed by UV‐visible reflectance spectra and X‐ray diffraction.
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S. Rajendran, B.V. Apparao and N. Palaniswamy
The inhibition efficiencies of 2‐carboxyethyl phosphonic acid (2 CEPA) – Zn2+ system and ethyl phosphonic acid (EPA) – Zn2+ system in controlling corrosion of mild steel in a…
Abstract
The inhibition efficiencies of 2‐carboxyethyl phosphonic acid (2 CEPA) – Zn2+ system and ethyl phosphonic acid (EPA) – Zn2+ system in controlling corrosion of mild steel in a neutral aqueous environment containing 60ppm CI– have been compared. Polarization study reveals that both the systems function as mixed inhibitors. The inhibition efficiencies of these systems decrease with period of immersion due to the dissolution of the protective film as the period of immersion increases. The 2 CEPA – Zn2+ system has a better inhibition efficiency than the EPA–Zn2+ system. This is due to the fact that the amount of Fe2+– 2 CEPA complex present on the metal surface is higher than that of Fe2+– EPA complex, as revealed by fluorescence spectra. The molecular size of the iron phosphonate complex exercises a greater influence than the electronic (inductive) effect of the substituent in controlling corrosion of mild steel in chloride environment.
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S. Rajendran, B.V. Apparao and N. Palaniswamy
The influence of a cationic surfactant, N‐cetyl‐N, N, N‐trimethyl ammonium bromide (CTAB) on the inhibition efficiency (IE) of calcium gluconate (CG) – Zn2+ system in controlling…
Abstract
The influence of a cationic surfactant, N‐cetyl‐N, N, N‐trimethyl ammonium bromide (CTAB) on the inhibition efficiency (IE) of calcium gluconate (CG) – Zn2+ system in controlling corrosion of mild steel in a neutral aqueous environment containing 60ppm Cl‐ has been evaluated by weight‐loss method. The formulation consisting of 200 ppm CG and 50ppm Zn2+ has 86 per cent IE (immersion period = three days). Addition of various concentrations of CTAB to the above system improves the IE to 99 per cent. Presence of CTAB facilitates the transport of CG and Zn2+ from the bulk of the solution to the metal surface. The nature of the protective film formed on the surface of mild steel has been analysed by FTIR and fluorescence spectra. The protective film is found to be fluorescent and to consist of iron‐CG complex, iron‐CTAB complex and Zn(OH)2.
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S. Rajendran, B.V. Apparao and N. Palaniswamy
2‐chloroethyl phosphonic acid (2‐Cl EPA) and Zn2+ show a synergistic effect in controlling corrosion of carbon steel in a neutral aqueous environment containing 60 ppm Cl‐. The…
Abstract
2‐chloroethyl phosphonic acid (2‐Cl EPA) and Zn2+ show a synergistic effect in controlling corrosion of carbon steel in a neutral aqueous environment containing 60 ppm Cl‐. The protective film consists of Fe2+–2–Cl EPA complex and Zn(OH)2; it is found to be uv‐luminescent.
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Susai Rajendran B. and N. Palaniswamy
The formulation consisting of 300ppm 1‐hydroxyethane‐1, 1‐diphosphonic acid (HEDP) and 50ppm Zn2+ offered 99 per cent inhibition to the corrosion of mild steel immersed in neutral…
Abstract
The formulation consisting of 300ppm 1‐hydroxyethane‐1, 1‐diphosphonic acid (HEDP) and 50ppm Zn2+ offered 99 per cent inhibition to the corrosion of mild steel immersed in neutral aqueous environment containing 60ppm chloride. This formulation functioned as a mixed inhibitor. The protective film was found to be luminescent and to consist of Fe2+‐HEDP complex and Zn(OH)2.
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Susai Rajendran, B.V. Apparao, V. Periasamy, G. Karthikeyan and N. Palaniswamy
The formulation consisting of 50ppm ATMP and 300ppm MoO42‐ had only 32 per cent efficiency in inhibiting the corrosion of mild steel immersed in a neutral aqueous environment…
Abstract
The formulation consisting of 50ppm ATMP and 300ppm MoO42‐ had only 32 per cent efficiency in inhibiting the corrosion of mild steel immersed in a neutral aqueous environment containing 60ppm C1‐, whereas the ATMP (50ppm) ‐ MoO42‐ (300ppm) ‐ Zn2+ (50ppm) system had 96 per cent inhibition efficiency. The lower inhibition efficiency in the former case was due to the dissolution of the protective film formed on the metal surface, and getting precipitated in the bulk of the solution; this system controlled the anodic reaction only. The latter system controlled both the anodic and cathodic reactions; the dissolution of the protective film formed on the metal surface was reduced to a greater extent.
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S. Rajendran, B.V. Apparao and N. Palaniswamy
The formulation consisting of 300ppm 1‐hydroxyethane‐1, 1‐diphosphonic acid (HEDP), 50ppm polyacrylamide (PAA) and 50 ppm Zn2+ offered 99 per cent corrosion inhibition and 99 to…
Abstract
The formulation consisting of 300ppm 1‐hydroxyethane‐1, 1‐diphosphonic acid (HEDP), 50ppm polyacrylamide (PAA) and 50 ppm Zn2+ offered 99 per cent corrosion inhibition and 99 to 99.9 per cent biocidal inhibition to mild steel in neutral aqueous environment containing 60ppm Cl‐ , a situation commonly encountered in cooling water systems. The nature of the protective film formed on the metal surface was analysed using X‐ray diffraction, UV‐visible reflectance, FTIR and luminescence spectra. The film was found to be luminescent and to consist of Fe2+ ‐HEDP complex, Fe2+ ‐PAA complex and Zn(OH)2.