Calculating Corrosion Inhibitor Adsorption and Desorption Rates Using Gradient-based and Data-Addition Methodologies

Abstract Accurately determining surfactant adsorption-desorption kinetic information is essential for understanding and optimizing corrosion inhibitor performance. Present methods rely on subjective inspection of the data resulting in inconsistent and difficult to reproduce analysis. This work addresses this challenge by developing two rigorous methods to identify the transition point between transient and steady-state conditions. The goal is to enable consistent calculation of adsorption (ka) and desorption (kd) kinetic rate constants, improving reproducibility in kinetic studies. The first method applies a gradient-based approach, identifying the point where the derivative of the corrosion rate data first vanishes to detect the transition point. The second method uses an iterative data-addition routine to fit experimental data by progressively truncating the corrosion rate curve. Each method was applied to a common dataset and compared for accuracy and performance. Both methods yielded statistically equivalent rate constants for adsorption and desorption, with excellent agreement in regression quality. Automation of both approaches provides a valuable consistency check, and their complementarity ensures reliability. The gradient-based method offers a faster, simpler workflow with minimal manual intervention, while the data-addition method provides greater scope for iterative fine-tuning. Together, these automated techniques offer robust, reproducible tools for kinetic analysis in corrosion inhibitor studies.