Inhibition Effects of 6-Substituted 1, 3, 5-Triazine-2, 4-dithiol Monosodium Salts on Corrosion of Copper

Abstract

The inhibition effect of 6-substituted 1, 3, 5-triazine-2, 4-dithiol monosodium salts (R-TDT) on the corrosion of copper in the ASTM aqueous solution without stirring at 501°C for 10-20 days has been investigated.The percent inhibition efficiency depended upon the structure of 6-substituted groups (R) in R-TDT and increased in the following order where R' was an alkyl or an, aryl group. The key atoms in the R groups seemed to play an important role for the inhibition of the copper corrosion. The R' groups with a large coverage area and with little steric hindrance gave a high inhibition efficiency. The concentration of RTDT, being effective for the inhibition of copper corrosion, was dependent upon R: x 10-6 mol/l for R'NH-TDT and 8 x10-6-10-4 mol// for (R'), N-TDT. Thee were good inhibitors in the pH range of 5.5-12. The inhibition efficiency of R-TDT decreased in the presence of salts such as NaCI, KCl, Na₂S₂O^2-, Fe2(SO₄)3, and (NaPO^2-)6, but the corrosive action of the salts could be inhibited upon increasing concentration of R-TDT.
R-TDT was found by polarization mesurements to act as an anodic inhibitor.
R-TDT such as C6H₅NH-TDT reacted easily with copper powder, Cu20, or CuO in water at 50°C for 72 hr. On the basis of the elemental analysis and infrared spectra of the obtained products, the chemical structure of the surface films appeared in this inhibition was discussed and generally indicated by the following structural formula.