%0 Journal Article
%T Corrosion Inhibition of Carbon Steel in 0.5£¿M H2SO4 by Phtalocyanine Blue
%A J. C. Valle-Quitana
%A G. F. Dominguez-Pati£¿o
%A J. G. Gonzalez-Rodriguez
%J ISRN Corrosion
%D 2014
%R 10.1155/2014/945645
%X Phthalocyanine blue dye has been investigated as a carbon steel corrosion inhibitor in 0.5£¿M sulfuric acid by using polarization curves, electrochemical impedance spectroscopy, and gravimetric tests. Dye concentrations included 0, 100, 200, 400, 600, 800, and 1000£¿ppm, whereas testing temperatures were 25, 40, and 60¡ãC. Results indicated that phtalocyanine blue is a good corrosion inhibitor with its efficiency increasing with the concentration up to 40¡ãC, but it increases at 60¡ãC. Inhibitor improves the passive film properties and it forms an adherent, compact, protective film, acting, therefore, as an anodic-type inhibitor. At 25 and 40¡ãC the corrosion process was under charge transfer, whereas at 60¡ãC the adsorption/desorption of some species from the metal surface controlled the corrosion process. 1. Introduction Organic compounds containing atoms such as nitrogen, sulphur, and oxygen are commonly used to reduce the corrosion attack on steel in acidic media. These compounds adsorb on the metal surface, block the active sites on the surface, and thereby reduce the corrosion process [1¨C6]. The inhibiting action of such compounds is based on the adsorption ability of their molecules, where the resulting adsorption film isolates the metal from the aggressive media. The corrosion inhibition of organic compounds is related to their adsorption properties. Adsorption depends on the nature and the state of the metal surface, on the type of corrosive environment, and on the chemical structure of the inhibitor [7]. Studies report that the adsorption of organic inhibitors mainly depends on some physicochemical properties of the molecule, related to its functional groups, to the possible steric effects and electronic density of donor atoms; adsorption is suppose, also to depend on the possible interaction of the -orbitals of the inhibitor with the d-orbitals of the surface atoms, which induce greater adsorption of the inhibitor molecules onto the surface of metal, leading to the formation of a corrosion protection film [8]. Recently, there has been a lot of attention paid to the use of organic dyes as potential corrosion inhibitors for different metalsenvironments [9¨C24]. Thus, Oguzie evaluated the use of Congo red [9], methylene blue [10], indigo blue [11], safranin-o, thymol blue, and fluorescein [12] as corrosion inhibitors for mild steel in acidic media, although in some cases they evaluated these dyes for aluminum in hydrochloric acid [13]. Alizarin yellow and Bromophenol blue have been used also but now studying the synergistic effect of iodide ions for the
%U http://www.hindawi.com/journals/isrn.corrosion/2014/945645/