Synthesis Of Benzimidazole Inhibitor And Its Application In Water-based Anti-rust Liquid

Metal corrosion not only destroies the workpiece in shape, color and mechanicalproperties, what’s more, it also causes direct or indirect economic losses. This papercombined the idea of green manufacturing, developed a new water-based anti rust liquidaiming at the short-term anti rust of carbon steel products. The main research contents andresults are as follows:(1) TGA, FT-IR, ESI-MS and1H-NMR were used to analyse the main composition andcontent of an existing import anti rust liquid. Monoethanolamine, monoethanolamineborate, sodium nitrite and other substances were found in it. Among which, sodiumnitrite had been banned to use in anti rust liquid in many countries at present for it had astrong carcinogenic tendency.(2) Three kinds of benzimidazole inhibitors with surface activities2-hexyl amino-4-(benzimidazolyl)-amino-6-(2-sulfo ethyl)-amino-1,3,5-triazine (C6B),2-octyl amino-4-(benzimidazolyl)-amino-6-(2-sulfo ethyl)-amino-1,3,5-triazine (C8B) and2-twelveamino-4-(benzimidazolyl)-amino-6-(2-sulfo ethyl)-amino-1,3,5-triazine (C12B) weresynthesized using cyanuric chloride, aliphatic amines, taurine and2-amino benzimidazole.Their structures were characterized by FT-IR, ESI-MS and1H-NMR.(3) Weight loss experiments, polarization curves, electrochemical impedancespectroscopy and scanning electron microscopy were used to study the inhibition action of2-amino benzimidazole, C6B and C8B on the corrosion of No.45steel in1mol/L HClsolutions. Compared with2-amino-benzimidazole, C6B and C8B exhibited better inhibitioneffect, and the inhibition efficiencies increased significantly with the inhibitor concentrationincreasing. Within the scope of the study, the corrosion inhibition performance improvedsignificantly with the increasing length of hydrophobic chains of the inhibitors. Thus C8B wasthe best. Under the testing temperature of25°C, the highest inhibition efficiency of C8B was found at the concentration of0.9g/L, which was98.6%. The results of polarizationcurves showed that both C6B and C8B acted as mixed type inhibitors with cathodic inhibitionas the dominative action.(4) The synthesized C6B was used to replace the sodium nitrite to optimize the importanti rust liquid and produce a novel water-based anti rust liquid. Taking the monolithic rusttest as the standard, the best formula was obtained through response surface methodology thatmonoethanolamine was6.23%, monoethanolamine borate was5.84%, C6B was0.41%,PEG600was0.5%, CMC was0.2%, organic silicon defoamer was0.05%(the remainingcomponent was water) and the optimum concentration was8%. It showed that within thescope of the study, the homemade water-based anti rust liquid showed excellent anti rustperformance and was slightly better than the import anti rust liquid by comparingthe physicochemical properties and the scanning electron microscopy results of them.