Gleichenia linearis Burm. Leaf extract as corrosion inhibitor of mild steel in hydrochloric acid medium

Resam or Gleichenia linearis Bunn. is one of a wild shrub that thrives in Indonesia forests. Using Gleichenia linearis Bunn. leaf extract as corrosion inhibitor of mild steel in 1 M HCl investigated by weight loss, potentiodynamic polarization, Fourier-transform infrared spectroscopy, and scanning electron microscopy methods. The results prove that the chemical content of Gleichenia linearis Bunn. leaf extract can inhibit the corrosion rate of mild steel and exhibit high inhibition efficiency. The use of 4 g/L Gleichenia linearis Bunn. leaf extract in 1 M hydrochloric acid medium has inhibited the corrosion of mild steel with an inhibition efficiency reaching 84.54%. The adsorption of this extract on the surface of mild steel follows Freundlich adsorption isotherm. Potentiodynamic polarization measurements showed that Gleichenia linearis Bunn. leaf extract was a type of mixed inhibitor with more anodic effectiveness. The results of the analysis of corrosion products, extracts, and mild steel surfaces show different infrared spectra between extracts and corrosion products. The mild steel surface is covered by the extract and shows a smoother, flat surface. Kinetic and thermodynamic parameters indicate that the extraction occurs spontaneously on mild steel surfaces. Corrosion inhibition of Gleichenia linearis Bunn. leaf extract occurs due to the physical adsorption process on the steel surface.