Study on corrosion inhibition by N-sulfonic amino-dimethylenephosphonic acid

The corrosion inhibition by SADP (N-sulfonic amino-dimethylene phosphonic acid) on 0Cr13 stainless steel was studied by linear polarization and anodic polarization curve methods in 0. 10mol/L H₂SO₄ solutions, compared with HEDP ( 1-hydroxyethylidene-1, 1-diphosphonic acid) and ATMP (aminotrimethylenephosphonic acid). It was found that these three phosphonic acids have remarkable inhibition effect on the corrosion of 0Cr13 stainless steel in H₂SO₄ solutions. The corrosion inhibition mechanism by SADP, HEDP, ATMP on 0Cr13 was found to be the geometric blocking effect. Results showed that the adsorption of all these three phosphonic acids follows the Langmuir adsorption isotherm. The order in the corrosion inhibition efficiency may be arranged as follows: ηSADP > ηATMP > ηHEDP.