The inhibitive synergistic effect between a cationic gemini surfactant, 1,3-propane-bis(dimethyl dodecylammonium bromide)
(12-3-12), and bromide ion for the corrosion inhibition of cold rolled steel in 0.5molL−1 H2SO4 was investigated by weight loss, potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The
inhibition system composed by 12-3-12 and bromide ion is efficient. The adsorption mechanism of the 12-3-12 and bromide ion
on steel in acidic medium is discussed on the basis of experimental data and an adsorption model is proposed. Adsorption of
inhibitor system on the mild steel surface in acidic medium obeys Langmuir’s adsorption isotherm. In addition, potentiodynamic
polarization studies show that the system acts as a mixed-type inhibitor. Electrochemical impedance spectroscopy also suggests
the formation of a protective layer on the steel surface by the adsorption of surfactant molecules and bromide ions.
"Such results indicate that the synergistic effect not only increases inhibition efficiency at less cost, but also provides more opportunities for choosing appropriate and environmentally safer inhibitors. Halide ions with surfactants have recently been shown as capable of obvious synergistic effect on the corrosion of metals in different acidic solutions (Amin et al., 2009; Bouklah et al., 2006; Eddy et al., 2009; Merah et al., 2008; Umoren and Ebenso, 2007; Wu et al., 2009). The important role of halide ions in maintaining the stability of surfactants on the metal surface has been confirmed and their inhibiting effects in acidic solutions have been shown to decrease in the order of I À > Br À > Cl À (Umoren et al., 2010). "
[Show abstract][Hide abstract] ABSTRACT: The purpose of this investigation is to propose a strategy for minimizing the creation of spent pickling liquors through the synergistic corrosion inhibition of OP-10 and potassium iodide, thus facilitating a cleaner production process for acid pickling of metals with a high-concentration solution (6.0 mol/l) of hydrochloric acid. Results obtained with the methods of weight loss and electrochemical polarization showed that adding KI and OP-10 could enhance the energy barrier of the corrosion reaction and improved the corrosion inhibition for mild steel in high concentration of HCl solutions. A synergistic effect was identified when KI and OP-10 were present in suitable proportions. The results of the electrochemical experiments and scanning electron microscope (SEM) observations showed that the complex inhibitor was a mixed-type inhibitor and it formed a compact film on the metal surface, thus providing an effective protection for the metal in the aggressive solutions, which significantly minimized the creation of spent pickling liquors. A simple and convenient method was also proposed for the quantificational evaluation of the inhibition degree in the creation of spent pickling liquors.
[Show abstract][Hide abstract] ABSTRACT: The electrochemical behavior of mild steel in sulfamic acid solution in the presence of a gemini cationic surfcatant, butanediyl-1,4-bis(dodecyldimethylammonium bromide (12-4-12), and its monomeric counterpart, dodecyltrimethylammonium bromide (DTAB), was investigated as a function of the surfactant concentration by means of electrochemical impedance spectroscopy (EIS). The critical micelle concentration (cmc) values of DTAB and 12-4-12 in 1M sulfamic acid solution, measured by surface tension measurement, were found to be 1.2 and 0.02mM, respectively. The EIS results revealed a higher charge transfer resistance in 12-4-12 solution compared to that in DTAB solution at the same concentration normalized by the cmc (c/cmc). The morphology of the steel samples after being exposed to the acidic test solutions was examined by atomic force microscopy (AFM). The AFM micrographs showed a reduction of surface roughness in the presence of the surfactant which is more evident at higher surfactant concentrations. The adsorption of both surfactants in the sulfamic acid solution was studied by Langmuir and Flory-Huggins adsorption isotherms at submicellar concentrations.
[Show abstract][Hide abstract] ABSTRACT: The influence of halide ions (Cl−, Br−, I−) on the corrosion inhibition efficiencies of various organic-type inhibitors including polymers, natural products of plant origin, organic dyes, surfactants, drugs etc. on metals corrosion in various aqueous aggressive environments and under different experimental conditions has been widely reported in the literature and is discussed in this paper. Most of the available data show that the halide additives synergistically increased the inhibition efficiencies of most organic cation-type molecules in the order Cl− < Br− < I− in the different environments investigated. Such synergistic effects often show sensitivity to various factors including nature and concentration of the additives, temperature as well as nature of the metal and aggressive environments. Mechanisms proposed for the synergistic interactions have been compared and evaluated with respect to the reported experimental data.
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