The electron donating effect of novel pyrazolo-pyrimidine inhibitors on anticorrosion of Q235 steel in picking solution

Abstract

Three pyrazolo-pyrimidine derivatives with different electron-donating groups named 4-hydroxy pyrazolo-pyrimidine (HPP), 4-amino pyrazolo-pyrimidine (APP) and 4-mercapto pyrazolo-pyrimidine (MPP) were researched as novel inhibitors on anticorrosion of Q235 steel in picking solution at 298 K. The corrosion resistance ability was tested by electrochemical methods (EIS, Tafel) and surface topography analysis (SEM, AFM). The inhibition process was further analyzed by quantum chemical calculations, the molecular dynamic (MD) simulation, energy dispersive spectrometer (EDS) and adsorption isotherm studies. These results show that the inhibition ability increased with the concentration of inhibitors and the maximal corrosion inhibition effect was up to 99% for MPP. It also demonstrates that the inhibition performance followed the order: HPP < APP < MPP, which agrees with the electron donating ability of substituents (-SH > -NH2 > -OH).