Water-soluble N-methylpolypyrrole nanoparticles as a highly efficient eco-friendly corrosion inhibitor for carbon steel in 3.5 wt% NaCl solution

Abstract

Metal corrosion is a significant problem in industrial units that can disrupt operations and increase costs. A corrosion inhibitor (CI) is an effective solution to this issue. Organic compounds are suitable and efficient CIs for carbon steel (CS) against corrosion. Among them, intrinsically conducting polymers (ICPs) are gaining traction in numerous industries due to their eco-friendliness, low cost, high stability, and simple production process. One of the major obstacles associated with employing ICPs as CI is their limited solubility in aqueous media. The present study aimed to synthesize water-soluble N-methylpolypyrrole (NmPPy) nanoparticles through a facile, rapid, and cost-effective approach. The successful synthesis of the NmPPy nanoparticles has been confirmed through characterization using scanning electron microscopic (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV–vis spectra. The effectiveness of NmPPy nanoparticles in protecting CS against corrosion in a 3.5 wt% NaCl solution with varying concentrations at ambient temperature was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements. The findings from the study indicate that the NmPPy nanoparticles exhibit a noteworthy corrosion protection capacity for CS. At a concentration of 300 mg L−1, the NmPPy acted as a mixed-type inhibitor and yielded around 95% inhibition efficiency. Moreover, the adsorption behavior of the particles followed the Langmuir isotherm model with chemical adsorption. Surface morphology analysis techniques, including scanning Kelvin probe (SKP), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX), have confirmed the development of a protective film on the CS. The analysis indicates that the CS has a smooth surface, and the NmPPy nanoparticles exhibit high inhibition efficiency. Therefore, the water-soluble NmPPy nanoparticles effectively inhibit CS corrosion in NaCl solution. They hold immense promise for the future development of advanced protective materials.