Preparation, Characterization, and Inhibition Effect of Novel Nonionic Gemini Surfactants Based on Sebacic Acid against Carbon Steel Corrosion in Acidic Medium

Three nonionic gemini surface active agents on the base of sebacic acid with different propoxylated units were prepared for this research work, and their forms were studied using infra-red and hydrogen nuclear magnetic resonance spectroscopy. The surfactants physical characteristics were determined. They were found to be inhibitors of the corrosion for carbon steel in a HCl solution. In this investigation, the weight loss and the electrochemical techniques were applied. All of the studied agents were shown to be persuasive inhibitors of corrosion, with inhibition efficiency values exceeding 99%. The efficiency of the inhibition was shown to improve as the surfactant concentration and the exposure time increased, as well as the number of propylene units per a surfactant molecule. The studied surfactants acted as mixed-type inhibitors, according to polarization studies. Surfactants were found to protect steel from acidic corrosion by physically adsorbing their molecules onto the steel surface and forming a protective barrier between the metal and the corrosive liquid, decreasing the corrosion rate. Surfactants adsorption followed the Langmuir adsorption isotherm. Atomic force spectroscopy was used to investigate the surface of the carbon steel as blank specimen and in an acidic solution. The acquired images, as well as the surface properties measured, agree with the results obtained via other techniques used.