Non‐Antibacterial Mechanisms of <scp> <i>Agave sisalana</i> </scp> Saponins‐Glycerol as a Green Inhibitor for Biofilm‐Induced Corrosion on Copper Surfaces

Green corrosion inhibitors have gained attention as natural and eco-friendly solutions for microbiologically induced corrosion in various industries. This study investigates the potential of Agave sisalana saponins (ASS) combined with glycerol, a green solvent, to control biofilm-induced corrosion on copper surfaces. Bacterial strains with strong biofilm-forming abilities were isolated from Koel River water and identified through 16S rRNA gene amplification. Phylogenetic analysis confirmed the presence of Acinetobacter spp., Exiguobacterium sp. BFR12y, and Solibacillus sp. BFR13. Structural characterization of ASS using FTIR spectroscopy, NMR, and high-resolution mass spectroscopy confirmed the surfactant properties of extracted saponins. The Agave sisalana saponins-glycerol combination (ASSG) exhibited no antibacterial activity at the tested concentrations. However, colony-forming unit (CFU/biofilm) counts, CLSM, and SEM revealed a significant biofilm inhibition efficacy of 80.14%. Corrosion rate and electrochemical impedance spectroscopy study demonstrated 76.42% corrosion inhibition. The inhibitory effect of ASSG was attributed to its adsorption onto metal surfaces, resulting in a reduction in bacterial motility and adhesion, and Cu₂O formation, as confirmed by motility assay, contact angle measurement, and Raman spectroscopy analysis. The findings suggest the potential use of the Agave sisalana saponins-glycerol combination as a green, prospective corrosion inhibitor, with promising applications in cooling water systems across various industries.