Corrosion inhibition and biocidal activity of a cationic surfactant

The inhibition efficiency (IE) of CTAB - Zn 2+ system in controlling corrosion of carbon steel in well water has been evaluated by weight loss method. Enumeration of microorganisms from well water and biocidal efficiency of inhibitor system (CTAB-Zn 2+ ) were also determined by serial dilution technique and spread plate method. The formulation consisting of 200 ppm of CTAB and 5 ppm of Zn 2+ shows an IE of 98%. Potentiodynamic polarization curves indicate that the CTAB ― Zn 2+ system functions as anodic inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. FTIR spectra suggest that the protective film consists of Fe 2+ - CTAB complex and Zn(OH) 2 . The optimum concentration of CTAB for destroying the bacterias viz. E. coli, Salmonella and Shigella is ≥ 25 ppm. At ≥ 25 ppm of CTAB, it shows 100% biocidal efficiency in well water containing 5 ppm of Zn 2+ .