Abstract:

In order to provide advice for the application of trisodium phosphate,the influencing factors of its corrosion inhibition performance were systematically studied.The corrosion inhibition effect of trisodium phosphate on the wastewater of a certain combined station was evaluated by static weight loss method,polarization curves and electrochemical impedance spectroscopy.The influence of other factors including calcium and magnesium ions concentration,oxygen content and temperature of the sewage medium on its corrosion inhibition performance was also estimated.Results showed that trisodium phosphate as an anodic corrosion inhibitor had obvious corrosion inhibition effect only when its mass concentration was greater than 25 mg/L. It must be noted that the application concentration should be higher than the minimum effective concentration.Moreover,the presence of calcium and magnesium ions as well as the increase of temperature would inhibit the corrosion inhibition effect of trisodium phosphate,while the appropriate oxygen content could promote the formation of oxide film on the steel surface and further promote the corrosion inhibition.In addition,field practice showed that trisodium phosphate had a good application effect as an inexpensive corrosion inhibitor.

Key words: oil area wastewater, corrosion inhibitor, trisodium phosphate, polarization curve, AC impedance