Composite corrosion inhibitor for restraining corrosion of carbon steel in seawater and preparation method thereof

The invention discloses a composite corrosion inhibitor for restraining corrosion of carbon steel in seawater and a preparation method thereof. The composite corrosion inhibitor consists of, by weight percentage, 22-30% of o-oxy-acetatebenzaldehyde-4-methyl pyridine acyl hydrazone, 0.6-4% of dehydroabietylamine o-vanillin Schiff base, 13-20% of zinc sulfate and 46-58% of Tween 80. Structurally, the acyl hydrazone contains carbonyl, hypo-amido and imino, and the dehydroabietylamine Schiff base contains iminos which all have O atoms and N atoms with big electronegativity and are easy to coordinate with the ions on the surface of metal to form a chemical adsorption layer; and the iminos all have C=N and aromatic ring structure and are easy to form rho-pi conjugation, so the dehydroabietylamine Schiff base has stable structure and is not as easy as other Schiff bases to hydrolyze. The joint use of the inorganic salt zinc sulfate and Tween 80 serving as surfactant together with the Schiff base in the composite corrosion inhibitor effectively improves the corrosion resistance of the film. The corrosion inhibitor is rich in material source, low in cost, low in toxicity and high in efficiency and does not cause pollution to the environment.