Synthesis and Corrosion Inhibition of Ethylenediamine Bis-Schiff Bases as Acidification Corrosion Inhibitors

Four bis-Schiff bases N, N'-dicinnamylidene-1, 2-diaminoethane (NDCE), N, N'-dibenzylidene-1, 2-diaminoethane (NDBE), N, N'-disalicylidene-1, 2-diaminoethane (NDSE) and N, N'-bis(4-dimethylaminobenzylidene)-1, 2-diaminoethane (NDDE) were prepared as acidizing corrosion inhibitors through condensation reaction using ethylenediamine and aromatic aldehydes as raw materials. The chemical structures of Schiff bases were confirmed by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The corrosion inhibition of the inhibitors to N80 steel in 15% HCl solution at 90℃ was investigated by static weight loss measurement and electrochemical testing. The results show that NDCE had the best corrosion inhibition than others, and the inhibition efficiency of NDCE reached 99.17% at a concentration of 0.75%. The adsorption process of NDCE onto the steel surface obeys Langmuir adsorption isotherm. NDCE is a mixed type inhibitor, which could effectively inhibit the corrosion in acid solution by forming protective layer on the surface of N80 steel.