Corrosion and Scale Inhibition Properties by Phosphate-free and Nitrogen-free Scale Inhibitor in Cooling Water System

The corrosion and scale inhibition properties of acrylic acid-oxalic acid-allylpolyethoxy carboxylate (AA-APEM9) were investigated by determining the corrosion and scale inhibition efficiency, the Tafel polarization curve and significant control of CaCO3 scales. The AA-APEM9 exhibits the highest inhibition efficiency of 81.4 % when the carbon steel immersion in 3 % NaCl solution. AA-APEM9 possess excellent CaCO3 inhibition, approximately 70.2 % at threshold dosage of 6 mg/L. Compared to T-225, HPMA, PAA, PESA, AA-APEM9, possessing PEG, shows a superior inhibitory efficiency. AA-APEM9 has the best inhibition because of possessing the greatest degree of polymerization of PEG among it. SEM and TEM images indicate that AA-APEM9 changes highly the morphology and size of CaCO3 crystals during the inhibition process. XRD analysis shows that the AA-APEM9 copolymer influence CaCO3 crystal crystallinity. AA-APEM9 may be a potentially useful corrosion and scale inhibitor in a cooling water system.