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

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.

2014 ◽  
Vol 10 (3) ◽  
pp. 2388-2402 ◽  
Author(s):  
M.P. Chakravarthy ◽  
Dr. K. N. Mohana ◽  
C.B. Pradeep Kumar

Dapsone derivatives Viz., 4, 4’-sulfonylbis(N-((1H-pyrrol-2-yl)methylene)aniline) (SBPMA) and 2-dimethylamino-5-[(4-{4-[(4-dimethylamino-benzylidene)-amino]-benzenesulfonyl}-phenylimino)-methyl]-benzene (DBBPB), a new class of corrosion inhibitors have been synthesized and their corrosion inhibition efficiency on mild steel in 0.5 M H2SO4 was investigated by mass loss,  Tafel polarization and AC impedance measurements. Potentiodynamic polarization studies showed that, these compounds behave as mixed type of corrosion inhibitors. The adsorption process was found to obey Langmuir isotherm model. Electrochemical impedance spectroscopy (EIS) studies revealed that polarization resistance (RP) increases and double layer capacitance (Cdl) decreases as the concentration of the inhibitors increases. Various thermodynamic parameters for the adsorption of inhibitors on mild steel were computed and discussed. FTIR, EDX and SEM analyses were performed to study the film persistency of the inhibitors.


Author(s):  
Prakash Katuwal ◽  
Ramesh Regmi ◽  
Susan Joshi ◽  
Jagadeesh Bhattarai

Effects of Nepal origin plant species of Vitex negundo, Catharanthus roseu, Aegle marmelos and Elaeocarpus ganitrus extracts on mild steel corrosion were explored in bioethanol (E100) and its blend (E15) in airtight condition at 25±2 °C using static immersion, inhibition efficiency and mechanism tests which were complemented with adsorption isotherms and potentiodynamic polarization studies. Corrosion resistance of the mild steel was increased with increasing 500-2000 ppm concentrations of each plant extract in E100 and E15 biofuels. Additions of V. negundo and C. roseus extract separately in both the biofuels seems to be more effective inhibition actions to prevent the mild steel corrosion than A. marmelos or E. ganitrus addition so as the corrosion rates of the mild steel in E100 and E15 are successfully lowered even than in commercial gasoline (E0). The results obtained from the corrosion rate revealed the order of the corrosion inhibition efficiency (IE) as V. negundo > C. roseus > A. marmelos > E. ganitrus. The maximum IE (IEmax) in V. negundo and C. roseus leaves was showed about 89-86% and 71-75%, respectively, at 2000 ppm concentration, in spite of the other two more plants leaf extract also used as the corrosion inhibitors for the mild steel in both E100 and E15 biofuels. The IE increased on increasing inhibitor concentration following the Langmuir and Temkin adsorption isotherms but decreased with immersion time which suggested that the corrosion inhibition mechanism is of physical type of adsorption of the leaves constituents on the mild steel surface. A. marmelos extract acted as an anodic type of inhibitor in E100 and E15, while E. ganitrus acted as mixed


Author(s):  
N’guessan Yao Silvère Diki ◽  
Nagnonta Hippolyte Coulibaly ◽  
Kadjo François Kassi ◽  
Albert Trokourey

The corrosion inhibition of mild steel by 7-(ethylthiobenzimidazolyl) theophylline (7-ETBT) in 1 M HCl medium was investigated through weight loss and Tafel polarization techniques within a temperature range of 298 to 318 K. The inhibition efficiency depends on the concen­tration of 7-ETBT and reaction system temperature. The maximum inhibition efficiency values of 90.73 and 87.06 %, respectively, were estimated using both weight loss and Tafel polarization techniques at 298 K. The results suggest spontaneous and predominant physical adsorption of 7-ETBT on the metal surface which obeys Langmuir isotherm model. Furthermore, Tafel polarization method revealed that 7-ETBT is a mixed-type inhibitor. Po­tentiodynamic polarization results are in accordance with weight loss data to a good extent.


RSC Advances ◽  
2016 ◽  
Vol 6 (19) ◽  
pp. 15639-15654 ◽  
Author(s):  
Chandrabhan Verma ◽  
L. O. Olasunkanmi ◽  
I. B. Obot ◽  
Eno E. Ebenso ◽  
M. A. Quraishi

The inhibition of mild steel corrosion in 1 M HCl by four 5-arylpyrimido-[4,5-b]-quinoline-diones has been investigated using weight loss, electrochemical, surface, and quantum chemical calculations and molecular dynamics simulation methods.


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