Optimization and Statistical Estimates of Locust Bean Pod Extract as an Inhibitor to Combat Corrosion on Aluminium Metal (AA3003) in Hydrochloric Acid

Abstract

To study the process of aluminium metal corrosion using locust bean pod as an inhibitor with a view to evaluating the weight loss, rate of corrosion, statistical data, and optimum process conditions in an aggressive medium was carried out using the gravimetry method. Optimization of the variables that affect corrosion of metals surface was undertaken with the aid of desirability function of the quadratic model in Response Surface Methodology (RSM). To obtain the maximum loss in weight of the aluminium metal in the presence of the locust bean pod inhibitor, four parameters were varied via; process time, the concentration of hydrochloric acid, locust bean pod extract concentration, temperature and their reciprocal effects on loss in weight aluminium metal were confirmed. The model predicted the optimum aluminium weight loss of 1.08187 g at 6.95 hours, 1.50 M, 111.98 ppm, and 64.12 ^oC for process time, hydrochloric acid concentration, locust bean pod extract concentration, and temperature, respectively. The existence of aromatic combination, and amine bond groups that are evidenced in locust bean pod FTIR analysis meet the descriptive qualities of typical corrosion inhibitors.  An increase in HCl concentration led to an increase in the rate of aluminium metal dissolution in the inhibited and uninhibited media. The highest corrosion rate values obtained were 105.50 mm/yr and 103.35 mm/yr for uninhibited and 20 ppm inhibitor concentration respectively at 1.5 M HCl concentration. The useability of locust bean pod extract as an inhibitor in mitigating corrosion of aluminium metal in oil and gas facilities in the presence of hydrochloric acid and its optimum process values were confirmed in this present study.