Hindawi Publishing Corporation International Journal of Corrosion Volume 2011, Article ID 548528, 8 pages doi:10.1155/2011/548528 Research Article Study of Temperature Effect on the Corrosion Inhibition of C38 Carbon Steel Using Amino-tris(Methylenephosphonic) Acid in Hydrochloric Acid Solution Najoua Labjar, 1, 2 Fouad Bentiss, 3 Mounim Lebrini, 2 Charafeddine Jama, 2 and Souad El hajjaji 1 1 Laboratoire de Spectroscopie Infrarouge, Facult´ e des Sciences, University Med V Agdal, avenue Ibn Battouta, BP 1014, Rabat 10000, Morocco 2 Unit´ e Mat´ eriaux et Transformations (UMET), Ing´ enierie des Syst` emes Polym` eres CNRS UMR 8207, ENSCL, BP 90108, 59652 Villeneuve d’Ascq Cedex, France 3 Laboratoire de Chimie de Coordination et d’Analytique, Facult´ e des Sciences, Universit´ e Chouaib Doukkali, BP 20, El Jadida 24000, Morocco Correspondence should be addressed to Souad El hajjaji, selhajjaji@hotmail.com Received 13 March 2011; Revised 17 July 2011; Accepted 12 August 2011 Academic Editor: Carmen Andrade Copyright © 2011 Najoua Labjar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tafel polarization method was used to assess the corrosion inhibitive and adsorption behaviours of amino- tris(methylenephosphonic) acid (ATMP) for C38 carbon steel in 1M HCl solution in the temperature range from 30 to 60 ◦ C. It was shown that the corrosion inhibition efficiency was found to increase with increase in ATMP concentration but decreased with temperature, which is suggestive of physical adsorption mechanism. The adsorption of the ATMP onto the C38 steel surface was found to follow Langmuir adsorption isotherm model. The corrosion inhibition mechanism was further corroborated by the values of kinetic and thermodynamic parameters obtained from the experimental data. 1. Introduction Corrosion inhibition of steel in acid solutions by different types of inhibitors has been extensively studied. The use of environmentally acceptable inhibitors is favoured. Phospho- nates are known to be environmentally friendly corrosion inhibitors, which form adsorbed layers on oxide- or hydro- xide-covered metal surfaces [1–4]. Many works can be found in the literature about the interactions between phospho- nates and iron or steels. In particular, Ochoa and al. [2, 4] studied the interaction between phosphonocarboxylic acid salts (monophosphonates) and carbon steel. Their environ- mental impact at usual concentrations for corrosion inhibi- tion is negligible [5, 6]. Moreover, in contrast to inorganic phosphorous compounds, they do not cause eutrophication. Their high stability to hydrolysis and resistance to degrada- tion is also beneficial. It was found that few inhibitors with acid-metal systems have specific reactions that are still effective at high temperatures as (or more) they are at low temperatures [7, 8]. A large number of investigations have studied the temperature effects on acidic corrosion and corrosion inhibition of iron and steel in HCl and H 2 SO 4 solutions [9–17]. In previous work [1], the improving of the corrosion resistance of C38 carbon steel in 1 M HCl solution using ATMP has been investigated at 30 ◦ C by means of gravimetric and electrochemical (ac impedance and Tafel polarisation) methods. We have found that this compound is efficient inhibitor in 1 M HCl and the corrosion inhibition is mainly controlled by a physisorption process. The antibacterial acti- vity investigations have been shown that the ATMP has an antibacterial effect against both Gram-positive and Gram- negative bacteria [1]. A great limitation of the inhibitor application is the fall down of their efficiencies at high tem- peratures. The effect of temperature on the inhibited acid- metal reaction is highly complex because many charges