Effect of Molybdate, Nitrite and Zinc Ions on the Corrosion Inhibition of Mild Steel in Aqueous Chloride Media Containing Cupric Ions

2008 ◽  
Vol 1 (1) ◽  
pp. 82-91 ◽  
Author(s):  
M. R. Ali ◽  
C. M. Mustafa ◽  
M. Habib
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibitor ◽  
Corrosion Inhibition ◽  
Steel Corrosion ◽  
Zinc Ions ◽  
High Concentration ◽  
Mild Steel Corrosion ◽  
Aqueous Chloride ◽  
Acidic Chloride ◽  
Presence And Absence

An investigation has been conducted on the corrosion inhibition of mild steel by molybdate, nitrite and zinc ions in aqueous chloride media containing cupric ions. Molybdate inhibits mild steel corrosion in near neutral and alkaline (pH 6 and above) chloride media and accelerates corrosion in acidic media (below pH 6) both in the presence and absence of cupric ions. Nitrite inhibits mild steel corrosion in chloride media at pH 4.5 and above, but accelerates corrosion below pH 4.5 both in the presence and absence of cupric ions. Molybdate and nitrite act as a synergistic corrosion inhibitor in chloride media with or without cupric ions at pH 4.5 and above. In the acidic region between pH 3 and 4.5, the combination can decrease corrosion with a low concentration of molybdate and high concentration of nitrite. These concentrations depend on the relative amounts of molybdate and nitrite present in the system. Zinc ions inhibit mild steel corrosion only in acidic chloride media. Based on the experimental results, mechanisms of action of molybdate, nitrite and zinc ions on mild steel corrosion in aqueous chloride media with or without cupric ions have been proposed.Keywords: Molybdate; Nitrite; Mild steel; Corrosion rate; Synergistic corrosion inhibitor.© 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v1i1.1053

Electrochemical Studies of some New Mannich Bases Compounds as Corrosion Inhibitors for Mild Steel in Acidic Media

2012 ◽  
Vol 538-541 ◽  
pp. 2329-2333 ◽  
Author(s):  
Hui Xia Feng ◽  
Jian Li ◽  
Xiao Hong Gao
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibition ◽  
Corrosion Inhibitors ◽  
Steel Corrosion ◽  
Mannich Bases ◽  
Maximum Efficiency ◽  
Tafel Polarization ◽  
Mild Steel Corrosion ◽  
Polarization Studies ◽  
Inhibition Property

The corrosion inhibition behaviour of four selected Mannich bases compounds,namely 3-((N-methyl,N-phenyl)-methyl)2,4-Acetylacetone(MPMAA),3-((N-phenyl)-methyl) 2,4-Acetylacetone (PMAA),3-((N, N-diethyl)-methyl) 2, 4-Acetylacetone(DMAA) and 3-((N, N-methyl)-methyl) 2, 4-Acetylacetone (MMAA) as corrosion inhibitors for mild steel in 1M HCl solutions. Tafel polarization methods were performed to determine the corrosion parameters and inhibition efficiencies. Experimental results showed that PMAA is an excellent inhibitor for mild steel corrosion in 1M HCl solutions; showing a maximum efficiency 92.3% at concentration of 40mg/L. Polarization studies showed that the Mannich bases compounds can be regarded as mixed-type inhibitors and the inhibition efficiency of the four inhibitors followed the order PMAA > MPMAA > DMAA > MMAA. Then scanning electron microscope (SEM)techniques were also employed to examine the mechanism of corrosion inhibition property.

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