Effect of Temperature and Acid Concentration on Rhizophora mucronata Tannin as a Corrosion Inhibitor

The effect of temperature and acid concentration on a newly formulated tannin as a corrosion inhibitor for carbon steel in oil and gas facilities was investigated. Corrosion rate of carbon steel in HCl acid solutions (0, 5, 10, 15, 20, 25 and 30%) by Rhizophora mucronata tannin (RMT) was studied using chemical (weight loss method) and spectroscopic (FTIR) techniques at various temperatures in the ranges of 26–70 °C. At 20% optimum concentration of acid, the FTIR result showed the presence of hydroxyl group, aromatic group, esters and the substituted benzene group, indicating the purity of the tannin. The increase in HCl acid concentration and temperature increased the corrosion rate, but the rate of corrosion was mild with RMT. Therefore, the use of RMT as a cost-effective and environmental-friendly corrosion-inhibiting agent for carbon steel is herein proposed