Preparation of supramolecular corrosion inhibitor based on hydroxypropyl-β-cyclodextrin/octadecylamine and its anti-corrosion properties in the simulated condensate water

Abstract

Purpose – This work was focused upon the main factors that influence the formation of a hydroxypropyl-β-cyclodextrin (HP-β-CD) supramolecular complex with octadecylamine (ODA) and their optimal processing conditions. The anti-corrosion properties of the products in the simulated boiler water condensate of power plants also needed to be tested. The paper aims to discuss these issues. Design/methodology/approach – A grinding method was applied to synthesize the supramolecular structures. Using Fourier transform infrared, X-ray diffraction and proton nuclear magnetic resonance spectroscopy (1H NMR), the specific structures of the complex were clarified. The anti-corrosion properties were obtained from gravimetric results, potentiodynamic polarization tests and electrochemical impedance spectroscopy measurements. Findings – The results reveal the highly soluble supramolecular complex could be formed between two HP-β-CD molecules and one ODA molecule at 85°C with a processing period of 15 minutes. In the condensate, the corrosion inhibition efficiency of the complex was over 95 percent, much higher than the inhibition efficiency of the hydrophobic ODA compound. Practical implications – The supramolecular corrosion inhibitor could be used as an anti-corrosion method for industrial boiler condensate to reduce the content of corrosive ions. In this way, it is easier to reuse the condensate without re-polishing. Originality/value – The research introduces supramolecular chemistry into corrosion science for the first time. The results provide a new option to modify the traditional corrosion inhibitors.