Synthesis of new bioactive leaf extract for corrosion inhibition of steel pipelines in the acidic medium of oil and gas industry

This manuscript investigated the corrosion inhibition and adsorption behavior of Dioscorea alata leaf extract on mild steel to explore their bioactive anti-corrosion potentials in 1M H2SO4 environment. It used chemical and electrochemical methods and phytochemical screening. The weight loss measurement revealed that samples with 1 to 5 g/300 ml extract recorded maximum inhibitory efficiency of 72.4, 78.4, 81.1, 81.5, and 83.3 %, respectively, within their first 5 days. Generally, their inhibitory efficacy has been observed to decrease with greater exposure time, while the computed Gibbs free energy of the adsorption process (ΔG°ads) values from the weight loss data ranged from -9.5491 to -9.7165 kJ mol-1, and the adsorption isotherm measurements corresponds well with the Temkin adsorption isotherm, demonstrating a physisorption reaction between the extract molecules and the surface of the coupons. Phytochemical screening showed steroids, saponins, and terpenes were active ingredients in the extract. On the other hand, the potentiodynamic test produced maximum percentage inhibition efficiency of 97.99, 31.51, 97.30, and 98.17 %, respectively, for 1 to 5 g/300 ml extract concentrations. The highest corrosion rate of 9.905e+003 mpy was obtained from the sample without extract. Based on the corrosion inhibition effectiveness of the extract obtained through both methods, it is suggested that the extract be added in the production of paints that are used to cover pipelines in the oil and gas industry. This is because it has chemicals in it like saponins, terpenes, and steroids that can stick to the metal's surface and inhibit corrosion in acidic media.