Performance and mechanism of a composite scaling–corrosion inhibitor used in seawater: 10-Methylacridinium iodide and sodium citrate

An environment-friendly scaling–corrosion inhibitor composed of 10-methylacridinium iodide (MAI) and sodium citrate (SC) was developed, whose scale inhibition performance were studied through weight loss, electrochemical techniques, static tests and surface analysis techniques (SEM, SECM, XPS, XRD). The optimum mass ratio of MAI and SC corrosion inhibition was found to be 1:2, and the optimum mass ratio of scale inhibition was 1:3. The experimental results showed that MAI–SC mixture as mixed-type scaling–corrosion inhibitor with excellent corrosion (ηw = 92.7%) and scale inhibition performance (ηCa = 98.3%). The electrochemical stability of the inhibitor film was investigated by chronoamperometry (CA). SEM and XRD simulations indicated that the MAI–SC mixture inhibitor can distort and disperse the crystal lattice of calcium carbonate without forming scale, and it plays a dominant role in the inhibition of calcite (110) surface growth. The structure-activity relationship between the molecule structure of the MAI–SC mixture and its scale–corrosion inhibition performance was discussed based on the quantum chemistry calculation.