The Extract of Siamih (Ageratum conyzoides L) Leaf as a Green Eco-Friendly Corrosion Inhibitor for the Mild Steel St. 37 in HCl Solution

The extract of siamih (Ageratum conyzoides L) leaf was tested as a corrosion inhibitor of St. 37 steel in HCl medium using weight loss method, potentiodynamic polarization, Fourier Transform Infrared (FT-IR) analysis, and Scanning Microscopy Electron (SEM) analysis. Based on the method of weight loss, it can be seen that the corrosion rate decreases with the addition of the extract of siamih leaf. The highest inhibitory efficiency was 85.33% with the addition of an extract of 8 g/L, without the addition of iodide ions. The effect of temperature causes the inhibition efficiency to decrease with increasing temperature. Potentiodynamic polarization measurements show that the extract of siamih leaf is a mixed type inhibitor. SEM analysis shows the difference in the surface of the steel immersed in HCl without and with the addition of the extract of siamih leaf. There was a change in the shift in the wavenumber shown by the FT-IR spectrum before and after the extract of siamih leaf was added. The extract of siamih leaf adsorption on the steel surface corresponds to the Langmuir adsorption isotherm.