The inhibitory effect of Chromolaena Odorata and Tithonia diversifolia on low-carbon steel in carbonic acid (H₂CO₃) environments for slurry pots in oil and gas applications

This study investigates the inhibitory effect of Chromolaena Odorata and Tithonia diversifolia leaf extract against the corrosion process of low-carbon steel in simulated carbonic acid (H₂CO₃) conditions, to develop a corrosion-resistant slurry pot for oil and gas applications. The plant extract was prepared through methanolic extraction, and its effectiveness as an inhibitor of corrosion was assessed by evaluating the weight loss and potentiodynamic polarization techniques. Examining the surface morphology before and after the period of immersion using a Scanning Electron Microscope (SEM) with an attached Energy Dispersive Spectrometer (EDS). Fourier-Transform Infrared (FTIR) was used to study the functional groups responsible for the inhibition, which validated that the corrosion inhibition mechanism is significantly influenced by the hydroxyl (O-H) and unsaturated (C=C) bonds present in the extract. The results from SEM provided evidence of decreased surface degradation with the addition of the extract. The weight loss study showed a significant reduction in corrosion rate with increasing extract concentration, resulting in an 83.33 % inhibitory efficiency with 0.5 g/L of Tithonia Diversifolia extract and 80.95 % inhibitory efficiency with 0.5 g/L of Chromolaena Odorata extract. With the inclusion of the inhibitor, the potentiodynamic polarization data showed a decrease in the density of the corrosion current from 250.00 μA/cm² to 38.00 μA/cm² and 27.45 μA/cm² for Tithonia Diversifolia Chromolaena Odorata extract, respectively. Likewise, there is an increase in polarization resistance from 190.08 Ω to 917.82 Ω and 909.47 Ω for Tithonia Diversifolia and Chromolaena Odorata extract, respectively. Overall, it was discovered that Tithonia diversifolia and Chromolaena Odorata are efficient and environmentally friendly inhibitors for low-carbon steel corrosion in carbonic acid solution with potential application in corrosion control mechanisms.