Benzalkonium chloride/titanium dioxide as an effective corrosion inhibitor for carbon steel in a sulfuric acid solution

In this study, the corrosion performance of carbon steel samples in 0.5 M sulfuric acid by the addition of novel inhibitors, 200 ppm of (25% and 50%) titanium dioxide nanoparticles in benzalkonium chloride, was thoroughly investigated. Gravimetric measurements, cyclic and linear potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and hydrogen collection by water displacement evaluated inhibition performance. Analogously, TiO₂/ILB (50%), TiO₂/ILB (75%), and ILB inhibitors enhanced corrosion protection with over 80% inhibition efficiency in electrochemical tests. In addition, weight loss and hydrogen collection measurements reached comparable results. According to potentiodynamic polarization curves, inhibitors exhibited dual behavior, but cathodic protection was more predominant. Scanning electron microscopy (SEM) was employed to examine the surface morphology before and after immersion using corrosion tests. The correlation between electronic properties and inhibition efficiencies of tilted inhibitors was determined by simple linear regression. Electronic properties were calculated for neutral and protonated forms using a polarizable continuum model by the DFT method at the B3LYP/6-311+G (d, p) level of theory. The active adsorbed sites of HM1-HM3 on the metal surface were determined by analyzing their corresponding electrostatic surface potentials (ESP). Furthermore, molecular dynamics simulations were performed to illustrate the most conceivable adsorption configuration between the inhibitors and metal surfaces.