Investigation of Temperature and Inhibitor Concentration Effect of Dipotassium Hydrogen Phosphate on the Corrosion of Carbon Steel in Sodium Chloride Solution

In this study, the inhibition effect of dipotassium hydrogen phosphate (DKP) on the corrosion behavior of carbon steel ASTM A۱۰۶ in a temperature range between ۲۵ and ۵۵ °C and an inhibitor concentration range between ۷ and ۲۳ mM in ۱ mM sodium chloride solution was studied by using the potentiodynamic polarization method. As the temperature rises from ۲۵ to ۳۵ °C, the corrosion current density increases from ۳۰ to ۱۲۰ μA /cm۲. Interaction between the inhibitor concentration and solution temperature showed that with an increase in temperature, the system will be passivated at higher concentrations of inhibitor. Adsorption mechanism of DKP was investigated by the help of thermodynamic parameters. By addition of ۷ mM DKP into the solution, the value of activation energy (Ea) decreased from ۸۲ to ۵۰ kJ/mol. This reduction in the presence of inhibitor indicates the chemical adsorption of inhibitor on carbon steel surface. In addition, results showed that the inhibitor is more efficient at higher temperatures e.g. when the solution temperature increases from ۲۵ to ۳۵ °C at a concentration of ۷ mM DKP, the inhibitor efficiency increases from ۳۳ to ۶۷ percent. The electrochemical observations were confirmed by scanning electron microscopy (SEM) and X-ray spectroscopy (EDS).

کلیدواژه ها:

Corrosion inhibitor ، Dipotassium hydrogen phosphate ، Potentiodynamic polarization ، Activation energy ، عارفی نیا ، رضا استادیار مهندسی شیمی ، دانشگاه فردوسی مشهد ، دانشکده مهندسی محققی ، امیر دانشجوی دکتری مهندسی شیمی ، دانشگاه فردوسی مشهد ، دانشکده مهندسی