Chitosan-Stabilized Selenium Nanoparticles: Enhanced Corrosion Inhibition for Carbon Steel in H2SO4 with Antibacterial Activity

Chitosan-stabilized selenium nanoparticles (Ch-Se NPs) were synthesized via a green route using ascorbic acid as a reductant. The synthesized Ch-Se NPs were characterized using TEM, DLS, Zeta potential, XRD, and FT-IR, revealing spherical particles with an average size of 59.8 nm and good colloidal stability (+17 mV). The dual functionality of Ch-Se NPs as corrosion inhibitors and antibacterial agents was investigated. Electrochemical and gravimetric measurements demonstrated that Ch-Se NPs act as a mixed-type inhibitor for carbon steel in 1.0 M H2SO4, achieving a maximum inhibition efficiency of 93.02% at 500 ppm. Adsorption studies indicated Langmuir isotherm behavior, involving both physisorption and chemisorption mechanisms. Surface morphology analysis (AFM and SEM) confirmed the formation of a protective film. Additionally, biological screening revealed significant antibacterial activity against S. aureus, K. pneumoniae, and E. coli with a minimum inhibitory concentration (MIC) of 50 µg/mL. These findings suggest Ch-Se NPs are a promising, eco-friendly candidate for industrial corrosion protection and environmental safety.