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.