Corrosion Inhibition and Adsorption Characteristics of Rice Husk Extracts on Mild Steel Immersed in 1M H₂SO₄ and HCl Solutions

摘要

Corrosion inhibition characteristics of extract of rice husk ash on mild steel in 1 M HCl and H2SO4was investigated in this work. The study was carried out using mass loss, inhibition efficiency, atomicadsorption spectroscopy (AAS), FT-IR spectroscopy and surface analysis as bases for assessing theinhibition and adsorption properties of the extract in the acid solutions. The analyses of the resultsshowed that the inhibition efficiency increased with increase in concentration of the inhibitor anddecreased with temperature in both acid solutions. The efficiency of the extract in HCl (96%) wasnoted to be more than in H2SO4 (86%) solution. Thermodynamic parameters revealed that theadsorption of extract onto the metal surface was spontaneous. FTIR results showed that the inhibitionmechanism was by absorption process, through the functional groups present in the extract. The SEMimages of the corrosion product confirmed the protection offered by the extract on the surface of themetal immersed in both media. The data obtained were fitted into Langmuir and Freundlich adsorptionisotherms though the Langmuir model was found to be better fitted than the Freundlich.