Evaluation of Microbiologically Influenced Corrosion Inhibition Behaviour of BIFILAC Drug on Mild Steel in Acidic and Saline Media

Recent research focuses on biofilm forming bacteria as potential corrosion inhibitor for the metallic surfaces. In the present study, commercially available BIFILAC tablets that contains Lactobacillus sporogenes 50 million, Streptococcus faecalis T-110 Joint Parliamentary Committee (JPC) 30 million, Clostridium butyricum TO-A 2 million and Bacillus mesentericus TO-A JPC 1 million used for the diagnosis or treatment of gastrointestinal disorders and bacterial infections is used as corrosion inhibitor for mild steel (MS) plates in 0.5 M H 2 SO 4 solution and 3.5% NaCl solution. The inhibiting nature of BIFILAC tablets is studied by various methods like weight loss measurements, potentiodynamic polarization studies, electrical impedance spectral studies and morphological analysis by atomic force microscopy (AFM). Weight loss measurements studies reveals that the concentration of 30 mL BIFILAC inhibitor in both the corrosion medium exhibit high inhibition efficiency. Further, kinetic and thermodynamic parameters for the corrosion of MS in the absence and presence of BIFILAC inhibitor is evaluated using Arrhenius and Transition state equations. Langmuir-adsorption kinetics reveals that the formation of biofilm by BIFILAC inhibitor on MS surface takes place via physisorption process. Potentiometric polarization studies showed the BIFILAC inhibitor as mixed type inhibitor in acid medium and as anodic inhibitor in 3.5% NaCl medium. Impedance studies confirms the increase of resistance charge transfer by the formation of passive biofilm of BIFILAC inhibitor on MS surface that renders the electron transfer between underlying MS plate and the corrosive medium. Morphological analysis using AFM further confirms the formation of passive biofilm on MS surface via the physisorption of BIFILAC inhibitor.