Corrosion inhibition of mild steel in stimulated cooling water by blends of molybdate, nitrite and picrate as new anodic inhibitor

Purpose - The purpose of this paper is to investigate how to improve the corrosion inhibition behavior of molybdate-based inhibitors for mild steel, using organic compounds containing a phenyl ring together with nitrite agent. As picrate contains a phenyl ring together with three substituent nitrite anions, it is used as an organic compound. In this study a new molybdate-based inhibitor was introduced with the composition of 60 ppm molybdate/40 ppm nitrite/20 ppm picrate. Inhibition efficiency of molybdate alone and with nitrite and picrate on the uniform corrosion of mild steel in stimulated cooling water was assessed. Design/methodology/approach - The inhibition efficiency of molybdate alone and with nitrite and picrate on the uniform corrosion of mild carbon steel in stimulated cooling water (SCW) was assessed by electrochemical techniques such as potentiodynamic polarization, electrochemical impedance (AC impedance) measurements and weight loss determinations at the room temperature. Studies of electron microscopy included scanning electron microscopy (SEM) photography and X-Ray energy dispersive (EDS) microanalysis were used. Findings - The results obtained from the polarization and AC impedance curves were in agreement with those from the corrosion weight loss results. The results indicated that the new inhibitor was as effective as molybdate alone, though at one quarter of the concentration range of molybdate, which is economically favorable. Originality/value - The paper demonstrates improvement in corrosion inhibition of mild steel in SCW via a blend of molybdate, nitrite and picrate as a new anodic inhibitor.