*Article* **Inhibitive Properties of Benzyldimethyldodecylammonium Chloride on Microbial Corrosion of 304 Stainless Steel in a** *Desulfovibrio desulfuricans***-Inoculated Medium**

#### **Chung-Wen Hsu 1, Tzu-En Chen 1, Kai-Yin Lo 2 and Yueh-Lien Lee 1,\***


Received: 13 December 2018; Accepted: 17 January 2019; Published: 18 January 2019

**Abstract:** Biocides are frequently used to control sulfate-reducing bacteria (SRB) in biofouling. The increasing restrictions of environmental regulations and growing safety concerns on the use of biocides result in efforts to minimize the amount of biocide use and develop environmentally friendly biocides. In this study, the antimicrobial activity and corrosion inhibition effect of a low-toxic alternative biocide, benzyldimethyldodecylammonium chloride (BDMDAC), on a 304 stainless steel substrate immersed in a *Desulfovibrio desulfuricans* (*D. desulfuricans*)-inoculated medium was examined. Potentiodynamic polarization curves were used to analyze corrosion behavior. Biofilm formation and corrosion products on the surfaces of 304 stainless steel coupons were examined using scanning electron microscopy (SEM), energy-dispersive X-ray spectrum, and confocal laser scanning microscopy (CLSM). Results demonstrated that this compound exhibited satisfactory results against microbial corrosion by *D. desulfuricans*. The corrosion current density and current densities in the anodic region were lower in the presence of BDMDAC in the *D. desulfuricans*-inoculated medium. SEM and CLSM analyses revealed that the presence of BDMDAC mitigated formation of biofilm by *D. desulfuricans*.

**Keywords:** microbial corrosion; sulfate-reducing bacteria; biocides; electrochemical test; confocal laser scanning microscopy
