Abstract

The present study was initiated with an objective of investigating a plant extract as an effective corrosion inhibitor useful for protection of carbon steel in aqueous environment containing chloride ions. For this purpose, the leaf extract of the plant ‘Aerva lanata’ belonging to Amaranthaceae family of genus Aerva was chosen. The required optimum concentration of the extract for an effective inhibition was found to be 5 %, resulting in the inhibition efficiency of 95 % against corrosion of carbon steel in 200 ppm of NaCl solution. The extract introduced as a corrosion inhibitor was found to be effective in the pH range from 4.0 to 9.0. The extract could retain its inhibition efficiency for about an immersion period of 60 days and also up to a temperature of 333 K. The 5 % extract was found to control corrosion of carbon steel in highly aggressive medium containing 300 ppm of NaCl also. In order to maintain the protective nature, the required concentration of the extract was 2 %. From these studies, it was inferred that the Aerva lanata leaf extract exhibits good inhibitive properties for carbon steel in aqueous environment in wide ranges of pH, temperature and aggressiveness of medium.

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