Use of Equisetum arvense extract as a novel green corrosion inhibitor for low carbon steel in 0.5M H2SO4

High cost, high toxicity and non-availability of organic inhibitors led to the use of naturalproducts as anti-corrosion material [1, 2]. For example, morus alba pendula leaves extract [1],Centaurea cyanus aqueous extract [2] and Saraca ashoka [3] have been reported as effectivecorrosion inhibitor for steel. In this research, for the first time, the extract obtained fromEquisetum arvense extract was studied as an environment-friendly corrosion inhibitor of lowcarbon steel in H2SO4 media. In this regard, electrochemical methods such as potentiodynamicpolarization and electrochemical impedance spectroscopy (EIS) were used. Investigation of theresults shows that the Equisetum arvense extract, with mean efficiency of 96.3% atconcentrations of 1.0 g/L have good inhibiting properties. Polarization curves designated thatEquisetum arvense extract is a mixed type inhibitor. The effect of temperature on the corrosioninhibition effect of Equisetum arvense extract was also studied by using potentiodynamicpolarization method in the temperature range of 35-65 °C. After obtaining the coverage surface(Ө), different types of adsorption isotherms were tested in all of temperatures. The resultsshowed that the extract is adsorbed on the surface of carbon steel according Langmuir adsorptionisotherm. The values of ΔGads for all temperatures were close to -17 kJ mol-1, which indicates theelectrostatic adsorption (physical adsorption) of the extracts molecules on the surface of themetal. Thermodynamic adsorption parameters (Kads, ΔGads) of inhibitor were calculated using theLangmuir adsorption isotherm. Activation parameters of the corrosion process such as activationenergies, Ea, activation enthalpies, ΔH*and activation entropies, ΔS*, were calculated by theobtained corrosion rates at different temperatures.

کلیدواژه ها:

Low Carbon Steel ، Acid Corrosion ، Equisetum Arvense Extract ، Electrochemical Polarization Method ، Electrochemical Impedance Spectroscopy