Inhibition of Mild Steel Corrosion in 1.0 M HCl by Water, Hexane and Ethanol Extracts of Pimpinella Anisum Plant

Corrosion inhibition of mild steel in 1 M hydrochloric acid by water, hexane and ethanol extracts of Pimpinella Anisum plant were study using weight loss and Tafel polarization curves. The effects of temperature on the corrosion behavior of mild steel in 1M hydrochloric acid with addition of extracts were also studied. The inhibition efficiency (IE) increases with increasing concentration of Pimpinella Anisum extracts but decreases with increasing the temperature. The adsorption of the extracts on the surface of metal follows a Langmuir isotherm model. Polarization studies show that the extracts behave as mixed type inhibitors. Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) study confirmed that the inhibition of corrosion of mild steel is through adsorption of the extracts molecules on the surface of metal. Gas chromatography-mass spectroscopy (GC-MS) results showed that anethole was the major compound of both Yemeni and Moroccan Pimpinella Anisum plant.