Inhibition of Steel Corrosion in Simulated Oilfield Acidizing Medium Using Metallic Soap from Local Biomaterial

Metallic soap prepared by saponification of melon seed oil ( Cucumeropsis mannii N) with copper (II) salt was investigated as corrosion inhibitor for mild steel corrosion in 1 M hydrochloric acid solution. Results reveal that the metallic soap inhibited the corrosion process by spontaneous physical adsorption of the phytochemicals of the seed oil onto the mild steel surface. The highest inhibition efficiency of 82.7% was obtained at 30°C with 10 g/L of the metallic soap, but this efficiency decreased with increase in temperature. The fractional surface coverage data best fitted into Temkin adsorption model which was used to predict the inhibitor-metal binding strength as a function of temperature. Atomic Absorption Spectrophotometric assessment of copper (II) ion composition in the inhibitor afforded a value within the safe limit for health, environment and personnel. Density functional theorem (DFT) studies provided supportive evidence of possible involvement of the fatty acid phyto-components in the adsorption process. The mechanism of inhibition was also predicted by applying the recent temperature coefficient of inhibition efficiency equation.