Abstract:
In this paper, the results of testing a new nonionic surfactant as a corrosion inhibitor in a 0.5M hydrochloric
acid solution are given. The corrosion inhibitor was synthesized by catalytic esterification of maleic
anhydride with polyoxyethylene sorbitan and further amidating of the ether with diethanolamine. The
structure and composition of the developed inhibitor were characterized by the methods of FT-IR and 1H
NMR spectroscopy. Results showed that the reagent MA/Tween-DEA effectively inhibited the corrosion of
carbon steel in hydrochloric solution with an optimal inhibition efficiency of 94 % (100 ppm) at 303 K from
weight loss test. Thermodynamic parameters such as adsorption heat (ΔHa), adsorption entropy (ΔSa) and adsorption
free energy (ΔGads) were obtained from experimental data of the temperature studies of the inhibition
process at five temperatures ranging from 303 to 343 K. The thermodynamic parameters of the corrosion
process were calculated in the absence and presence of inhibitor and discussed. The mechanism of action of
inhibitor protection of a steel plate by a synthesized inhibitor has been studied. Adsorption of MA/Tween-
DEA on the carbon surface in 0.5 M HCl follows the Langmuir isotherm model.
