EFFECTIVENESS OF Mimosa pudica EXTRACTS AS A BENIGN ANTI-CORROSION ADDITIVE.

This research investigated the suitability of Mimosa pudica leaf (MPL) and Mimosa pudica stem (MPS) extracts as an inexpensive and nontoxic corrosion inhibitor for mild steel in acidic environment. The experiments carried out to investigate the corrosion inhibition of mild steel in 1.0 M HCl and 0.5 M H2SO4 by Mimosa pudica leaf and stem extract were weight loss and potentiodynamic polarization methods to determine the extract adsorption potential, kind of protection and its corrosion inhibition efficiency. These parameters were evaluated and interpolated to map out the variations with time and extract concentration using Origin Pro8.0 and Power suite software. The data obtained were analyzed using Design Expert software to determine the optimum combination of extract concentration and exposure time to achieve maximum inhibition efficiency. The protection efficiency of the inhibitors were found to increase with increase in concentration of the inhibitor showing an optimum inhibition efficiency of 99% at 1000mg/L concentration of MPS inhibitor in 1.0 M HCl solution and 96% at the same concentration of MPL in the same acidic solution and in 0.5M H2SO4, the optimum inhibition efficiency was found to be 99% at 1000mg/L concentration of MPS extract and 97% at the same concentration of MPL in the same acidic solution. The inhibitor efficiencies determined by weight loss and polarization methods are in reasonable agreement. Based on the polarization results, the investigated MP extract can be classified as mixed-type inhibitor. The adsorption model obeys to the Langmuir adsorption isotherm. The result also revealed that MPS performs better than MPL in both acidic medium and that the efficiency of both extracts decreases with time. This suggests that MP extract is a good alternative corrosion inhibitor. It is therefore concluded that, to maximize the efficiency of MP extract, there is need to stabilize it to ensure a lasting efficiency with time.