Evaluation of Nitrilotrimethylene Phosphonic Acid and Nitrilotriacetic Acid as Corrosion Inhibitors of Mild Steel in Sea Water

The inhibition efficiency of nitrilotrimethylene phosphonic acid (NTP) in controlling mild steel corrosion in sea water has been evaluated by galvanostatic polarization, electron scanning for chemical analysis (ESCA), and scanning electron microscope (SEM) methods. The results are compared with those obtained for nitrilotriacetic acid (NTA). NTP is found to be more effective in protecting mild steel against sea water corrosion as compared to NTA. The surface of mild steel in presence and absence of NTP and NTA is characterized by ESCA and SEM. From the ESCA studies, it is found that NTP formed a stable and compact film over the mild steel.