Corrosion Inhibition of Chito-Oligosaccharide to Q235 steel in Seawater

The corrosion inhibition of chio-oligosaccharide (COS) and compound inhibitors of COS and inorganic inhibitors to Q235 steel in seawater was investigated by corrosion immersion test, scanning electron microscopy (SEM) and electrochemical experimental methods. The electrochemical experimental results show that the inhibition efficiency hit the maximum of 65.73% when COS was added individually. The synergetic inhibition efficiency of COS compounded with NaNO₂ in seawater was 90.67%, and this compound inhibitor exhibited anodic type. The largest synergetic inhibition efficiency of COS compounded with Na₂MoO₄ was only 71.65%, and the COS and Na₂MoO₄ inhibited mutually. In corrosion immersion test the inhibition efficiency was the best with the value of 85.90%, when COS was compounded with NaNO₂. The mechanism of COS on the surface of Q235 steel was monomolecular adsorption, a spontaneous chemisorption process. The absorption of COS on the surface of Q235 steel obeyed the Langmuir model.