ORIGINAL PAPER Investigation of 2-aminoethanethiol as corrosion inhibitor for steel using response surface methodology (RSM) Gözde Tansuğ & Tunç Tüken & Nur Kıcır & Mehmet Erbil Received: 17 April 2013 /Revised: 20 June 2013 /Accepted: 20 July 2013 /Published online: 4 August 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract The inhibition efficiency of 2-aminoethanethiol (2- AEE) has been investigated against steel corrosion in 0.1 M HCl solution. The effect of temperature, pH, and concentra- tion were studied with the help of potentiodynamic measure- ment, electrochemical impedance spectroscopy, scanning electron microscopy, and atomic absorption spectroscopy techniques. The potential of zero charge (E pzc ) studies showed that the adsorption occurs via -SH group; the metal surface is positively charged in corrosive test solution. The adsorptive interaction is evaluated, and best correlation was obtained with Langmuir isotherm. 2-AEE was shown to have signifi- cant inhibition efficiency against steel corrosion. The response surface methodology was employed to explain the relation between pH, inhibitor concentration, and the efficiency. The regression analysis was realized for development of an equa- tion between independent variables and the output. The suc- cess of fitting model was tested with basic statistical argu- ments, residual and variance analysis, T and F tests, and R 2 value. The statistical evaluations showed that the obtained polynomial equation can be successfully used for optimization of applications involving the use of 2-AEE as inhibitor. Keywords Electrochemical characterizations . Electrochemical stability . Modeling . Electron microscopies Introduction The organic inhibitors are widely used for prevention of acid corrosion in various industrial processes like pickling, descaling, oil well acidizing, and cleaning [1–5]. The efficiency is strictly related to adsorptive interaction with the metal surface, via electron rich functional groups. The sulfur containing com- pounds are generally known to have higher efficiency among this type of inhibitors [6–10]. Environmental concerns are push- ing forward the studies, aiming to develop new inhibitors, so green and film assembling inhibitors have been frequently stud- ied [11–15]. For the same reason, the utility should also be improved and optimized in order to employ fewer chemicals in practical applications. Inhibitor application in open cooling water systems in- volves specifically designed inhibitor mixture formulation with co-additives (anti scaling agents, biocides, etc.), taking into account the characteristics of the system [4]. In any industrial corrosion protection application, the environmental conditions exhibit inconsistency in a definite range. Therefore, all significant parameters (pH, temperature, inhibitor concen- tration, possible ions) must be well controlled and optimized for the success of inhibitor application. In recent years, Goh et al. reported the study subjecting the evaluation of the effect of pH, contact time on phosphate inhibition for copper corro- sion. They utilized the response surface methodology (RSM) for optimization of independent variables in order to get highest utility with protection [16, 17]. Since the efficiency of an organic inhibitor is proportional to its ability for physical adsorption, the temperature and pH have vital importance for the efficiency. Variable temperature con- ditions affect the adsorption–desorption equilibrium of mole- cules on the surface. Also, the pH is important for the metal surface morphology; some corrosion products may exist on the G. Tansuğ (*) Mechanical Engineering, Ceyhan Engineering Faculty, Çukurova University, 01960 Adana, Turkey e-mail: gozde.tansug@gmail.com T. Tüken : N. Kıcır : M. Erbil Chemistry Department, Faculty of Science and Letters, Çukurova University, 01330 Adana, Turkey Ionics (2014) 20:287–294 DOI 10.1007/s11581-013-0966-2