Experiment design for copper corrosion inhibition using an expired drug

This study investigates the use of a liquid pharmaceutical drug as a corrosion inhibitor for copper in 1M perchloric acid, aiming to explore environmentally friendly corrosion protection solutions.

Response Surface Methodology (RSM) was employed to optimize and model the inhibition efficiency based on key experimental parameters: drug concentration (0.1% to 0.5%), temperature (20°C to 60°C), and immersion time (0.5 to 1.5 hours).

A quadratic model was developed to predict inhibition efficiency. Upon careful examination of the main effect coefficient plot, it was observed that a negative sign in the coefficients signifies an antagonistic effect of the factors on inhibition efficiency, whereas a positive sign indicates a synergistic effect, enhancing the efficiency of the inhibitor. The optimization process identified conditions that yielded the highest inhibition efficiency (99.71%), specifically at a drug concentration of 0.49%, a temperature of 20.71°C, and an immersion time of 1 hour. The experimental design was validated by a high coefficient of determination (R² = 0.994), an adjusted R² of 0.986, and a predictive Q² value of 0.945, all of which indicate strong model reliability.

This study highlights the practicality of repurposing pharmaceutical compounds for corrosion inhibition, thereby contributing to green chemistry by promoting the use of environmentally benign substances. The successful application of RSM underscores its utility in optimizing corrosion inhibition processes. The findings encourage further exploration of pharmaceutical inhibitors in various corrosive environments, suggesting potential advancements in sustainable corrosion protection strategies.