Corrosion Inhibition of Mild Steel in 1M Hydrochloric Acid using Haematostaphis barteri Leaves Extract

Phytochemical analysis was carried out on Haematostaphis barteri leaves extract to determine the biological constituent present in the extract for corrosion inhibition application. Also, weight loss technique was used to study the corrosion inhibition efficiency of the extract on mild steel in 1 M hydrochloric acid (HCl) at varied concentrations (13, 26 and 40 g/l) and temperatures (301, 313 and 323 K). The phytochemical analysis results showed the presence of alkaloids, flavonoids, tannins, phenolic compound, saponins, and the absence of cardiac glycosides. The inhibition efficiency of the extract was directly proportional to the concentration, but inversely proportional to the temperature. The highest efficiency was 73.74%, at 301 K and a concentration of 40 g/l. The standard free energy were negative values under all the studied conditions. The extract's corrosion inhibition mechanism was found to be spontaneous and was by mixed adsorption (comprehensive). The Temkin and modified Langmuir (El-Awady) adsorption isotherms were plotted in order to show the adsorption pattern of the inhibitor on the metals surface. The data obtained fits both adsorption isotherms. (C) 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the organizing committee of SMPM 2019.