Corrosion inhibition and adsorption mechanism studies of Hunteria umbellata seed husk extracts on mild steel immersed in acidic solutions

The corrosion inhibition characteristics of Hunteria umbellata seed husk extracts on mild steel immersed in 1 M HCl and H2SO4 solutions were investigated. Mass loss, atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used as basis for studying the corrosion inhibition behavior of the extracts. The results show that the extracts contain OH, CN and unsaturated CC functional groups which were identified as contributing to the inhibition exhibited by the extracts. The inhibition efficiency was found to increase with increase in extract concentration in the acidic solutions but decreases with increase in temperature. Specifically, the inhibition efficiency of the extracts was observed to be generally very high but more effective in 1 M HCl compared to 1 M H2SO4 solution. Langmuir isotherm best fits the data obtained suggesting physical adsorption as the adsorption mechanism between the extract and the mild steel substrate.