| Based on the silicone and organic phosphine compound have excellent corrosive performance, in this paper the compounds containing two phosphonate radicals, N, N-dimethylenephosphonic acid propylamine (DPPA), N, N-dimethylenephosphonic acid aminopropyl dimethyl-silanediol (DPDS) and N, N-dimethylenephosphonic acid aminopropyl methyl-silanediol (DPMS), were designed and synthesized via Mannich reaction. At the same time polysiloxane containing phosphonic acid ester was also prepared. Polarization curves and electrochemical impedance spectroscopy (EIS) results indicated that three compounds behaved as mixed-type inhibitors for the corrosion of iron in H2SO4 solution. Fourier transfer infrared spectroscopic (FT-IR) analysis and X-ray Photoelectron Spectroscopic (XPS) characterization demonstrated that all of DPPA, DPDS and DPMS molecules bound to the iron substrate through interaction of phosphonate radicals with oxidized iron surface. At the same time, Langmuir adsorption isotherm model was found to be a good description for the adsorption behavior of three inhibitors on the iron surface. The adsorbed DPMS molecules with the process of hydrolysis and polycondensation of silicon hydroxyl could self-organize into a more compact protective layer than adsorbed DPPA or DPDS molecules, and the stability of the self-assembled film would be further strengthened on the metal surface. As a result, DPMS showed the better inhibition efficiency than DPPA or DPDS. In order to further study the organic silicon corrosion inhibitor, this paper also studied the corrosion inhibition of EDTMS, HDTMS, PAES and EDPP through the polarization curves. According to the test, in a certain extent the number of adsorption center and molecular weight can be influenced the cover area and stability on the metal surface.Corrosion inhibition performance can be improved via the synergistic effect. In order to improve the corrosion inhibition performance of DPDS, we studied the corrosion inhibition of DPDS and inorganic salt. Polarization curves and electrochemical impedance spectroscopy (EIS) results indicated that this compound behaved as mixed-type inhibitors for iron in H2SO4 solution. Similarly, the analysis of FT-IR and XPS confirmed the adsorption of DPDS/KI on the iron surface. And the adsorption process of DPDS/KI was determined to be chemisorption. The analysis of synergism parameter, the combination of DP AS and KI displayed very good synergistic effect in the corrosion inhibition of iron. In acid medium, iodine ions firstly adsorbed on metal surface. And then the adsorption center of the inhibitor molecules adsorbed on the layer of iodine ions. As a result, this phenomenon enhanced the adsorption stability of DPDS on the metal surface. Thereby synergistic effect has good corrosion resistance performance for the metal. Compared with the corrosion inhibitor of DPDS, the corrosion inhibition was enhanced after the addition of KI obviously.Based on organic phosphine has better scale inhibition performance, this paper study the scale inhibition performance of DPP A, DPDS and DPMS. The scale inhibition performance of DPMS was slightly higher than the scale inhibition performance of DPP A or DPDS. |
