Electrochemical and Theoretical Studies on Amino Phosphonates as Efficient Corrosion Inhibitor for N80 Steel in Hydrochloric Acid Solution

Abstract

Amino phosphonate compounds, namely, dimethyl-(4-methoxyphenyl) (phenylamino) methyl phosphonate (DMMP) and dimethyl phenyl (phenylamino) methylphosphonate (DPMP) were synthesized and studied as inhibitors for N80 steel corrosion in 15% HCl solution using the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Polarization studies showed that both studied inhibitors were of mixed type in nature. The adsorption of inhibitors on the N80 steel surface obey Langmuir adsorption isotherm. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM) were performed for surface study of uninhibited and inhibited N80 steel samples. Density functional theory (DFT) was employed for theoretical calculations.