Quenching of Phen Green-SK Quantifies Metal Corrosion in Ethanol-based Environments

The corrosive chemical reactions that occur at metal interfaces are not well understood in non-aqueous environments. We demonstrate that the corrosion of carbon steel 1045 and aluminum can be quantified by chelation enhanced quenching of Phen Green-SK (PGSK) in ethanol-based solutions. We first evaluate the dependence of fluorescence intensity of PGSK on iron and aluminum ions concentrations respectively. Subsequently, we apply PGSK to examine the anodic dissolution of metal corrosion. The observed time-dependent chelation enhanced quenching of PGSK quantifies the corrosion rates of two metals over 24-hour immersion in ethanol-based solutions. The PGSK-based quantification of corrosion is compared to scanning electron microscopy and electrochemical techniques, including open circuit potential and Tafel extrapolation. The corrosion rates calculated from chelation enhanced quenching of PGSK and Tafel extrapolation are in agreement, and both indicate a decrease in corrosion rates over 24-hour. Our work shows PGSK can efficiently quantify anodic chemical reactions at metal interfaces, especially in organic solvents or other non-aqueous environments where the application of electrochemical techniques is limited by the poor conductivity of surrounding medium.