Red Onion Skin Extract-formaldehyde Resin as Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Solution

The resin formed with red onion skin extract (ROSE) and formaldehyde has been studied as a possible inhibitor for corrosion of Mild Steel in 1 M HCl at 30-50°C by weight loss measurement. The corrosion rate of mild steel and the inhibition efficiencies of the resin were calculated. The studies reveal that at constant acid concentration, the resin acts as an effective inhibitor for mild steel corrosion in HCl media. Inhibition efficiency increases with increase in the concentration of the resin but decreases with an increase in temperature. The adsorption of the resin was in accordance with the Langmuir adsorption isotherm at all the temperature studied. The mechanism of physical adsorption is proposed for the inhibitory action of the resin based on observed decrease in inhibition efficiency with increase in temperature.