Optimization of the parameters influencing the inhibition efficiency of 6063 Al alloy in 0.5 M NaOH using response surface methodology

In this study, the influence of two process parameters (concentration of inhibitor and temperature) on the corrosion current density and inhibition efficiency of 6063 Al alloy in 0.5 M NaOH environments using Coriandrum Sativum L. Extract (CSE) were examined by response surface methodology (RSM). The parameters considered for the study were found in 5 levels: temperature (X₁) at 30, 35, 40, 45 and 50⁰C and concentration of inhibitor (X₂) at 0.1, 0.2, 0.3, 0.4 and 0.5 g/l was taken to correlate the parameters with the inhibition efficiency as an output parameter. A regression model was established and authenticated before the parameters were optimized for the highest inhibition efficiency. The results revealed that the concentration of inhibitor has the significant effect on the inhibition efficiency followed by temperature, and the data predicted by regression analysis had a good agreement with the data obtained from the experiments with the values of R² = 0.9921 and Adj-R² = 0.99 for inhibition efficiency. The optimum settings for the studied parameters were found to be at temperature (30⁰C) and concentration of inhibitor (0.5 g/l) to achieve maximum inhibition efficiency of 74.11%. The study has also shown that the data obtained from response surface design is an effective technique for forecasting the optimum parameter setting required to maximize inhibition efficiency of 6063 Al alloy in 0.5 NaOH solution by incorporating all parameters under consideration.