The Use of Citrullus Lanatus for Corrosion Inhibition of A36 Steel in a CO2 Saturated Saline Solution: A Thermodynamic and Kinetic Model Approach

Citrullus lanatus was tested for its suitability as an Inhibitor on Mild Carbon Steel in a Carbon (IV) Oxide (CO2) saturated saline solution. The mechanism of corrosion was investigated with and without Inhibitor additive in order to compare the effectiveness of the Inhibitor. Thermodynamic computations namely Enthalpy, Entropy and Gibbs free energy were used to determine the Inhibitive property of the Citrullus lanatus Extract.  In addition, four Kinetic Models namely; Langmuir, Temkin, Flory-Huggins and Frumkin were also used to fit the experimental data. Gas Chromatography-Mass Spectroscopy and Fourier Transfer Infrared Spectroscopy were used to characterize the Watermelon Seed Extract. Analysis of the results shows that Inhibitor efficiency decreases with increasing Temperature. The result also shows Inhibition efficiency within the range of 17.39%-71.79%. From the Result, the test sample without Inhibitor has the least Activation Energy in comparison with those with Inhibitor additives. The investigation also revealed that the Frumkin model at 50oC best fits the Experimental data with a Coefficient of determination, R2 of 99.9%, though; the other Models also fit the Experimental data

Influence of PH, Immersion Time and Inhibitor Concentration on the Corrosion Inhibition Characteristic of Citrullus Lanatus Extract on A36 Carbon Steel in A CO2 Saline Solution

The use of Watermelon Seed Extract was employed to monitor the corrosion process of A36 Carbon Steel using varying pH (3.15-8.0), Immersion Time (24hrs-120hrs) and Inhibitor Concentration (50-200ppm). A 3.5wt% Sodium Chloride solution was prepared by dissolving 3.5g of NaCl in deionised water. Carbon (IV) oxide gas was bubbled onto the saline solution with the corresponding Ph measured and recorded using a calibrated Ph Meter (HANNA). Varying concentration (50-200ppm) of the Inhibitor was introduced into the Solution. A36 Carbon Steel Coupon was immersed into the CO2 Saline solution of varying PH. Weight Loss and Inhibition Efficiency was employed to test the investigation. Scanning Electron Microscope Analysis on the surface morphology of the Carbon Steel Coupon with and without the Inhibitor was carried out to corroborate the findings