Chitosan was used as the raw material. A quaternization reaction was carried out between 2,3-epoxypropyltrimethylammonium chloride and water-soluble chitosan to prepare quaternary ammonium salt water-soluble chitosan (QWSC), and its corrosion inhibition performance against the corrosion of carbon steel in stone processing wastewater was evaluated. The corrosion inhibition efficiencies of QWSC on carbon steel in stone processing wastewater were investigated through weight loss, as well as electrochemical and surface morphology characterization techniques. The results show that QWSC has superior corrosion inhibition performance for A3 carbon steel. When an amount of 60 mL·L−1 is added, the corrosion inhibition efficiency can reach 59.51%. Electrochemical research has shown that a QWSC inhibitor is a mixed-type corrosion inhibitor. The inhibition mechanisms of the QWSC inhibitor revealed that the positive charge on the surface of carbon steel in stone wastewater was conducive to the adsorption of Cl− in the medium, which produced an excessive negative charge on the metal’s surface. At the same time, the quaternary ammonium cation and amino cation formed in QWSC in stone processing wastewater can be physically absorbed on the surface of A3 carbon steel, forming a thin-film inhibitor to prevent metal corrosion.
