The Polymerization Of Brominated-N-m-benzylamine Pyridine Propargyl Alcohol And Corrosion Inhibition For X70 Steel

Acid solution is widely used in steel pickling and oil refining equipment cleaning,in acidic conditions,metal corrosion not only lead to increased production costs but also endanger the safety of the operator.So,anti-corrosion is an eternal challenge for the scientists and engineers,and the research and development of efficient,low toxicity and environmental begnin corrosion inhibitors are a lasting issue.From the point of view of molecular design,brominated-N-m-benzylamino-pyridine and propargyl alcohol were covalently linked to construct the present inhibitor,so that these two moieties in the target molecule to cooperate synergetically agaist steel corrosion in acid solution as a good corrosion inhibitor.The triple bond and aniline units in target compound can form a three-dimensional network structure on the steel sheet by way of in situ polymerization,hindering the desorption of organic polymer molecules from the metal surface at high temperature and the loss of corrosion inhibitor performance as the small inhibitor molecules do at high temperature.Aniline moiety can polymerize in the acidic solution.It offers the posibility of coupling the polymerization and corrosion inhibition.So,the in situ polymerization and corrosion inhibition carries out simutaneously.Therefore,in this paper,p-chloromethylpyridine hydrochloride,propargyl alcohol and 3-?bromomethyl?phenylcarbamic acid tert-butyl ester were used as raw materials to synthesize the new brominated-N-m-benzylaminopyridine propargyl alcohol?designated as BAP?corrosion inhibitor.The corrosion inhibition performance of BAP on X70 in 5 M HCl solution was studied by BAP solution and BAP in situ polymerization on X70 steel surface.The main contents of this paper are as follows:1)The novel corrosion inhibitor BAP,which has not been reported,has been synthesized and characterized by ¹H NMR,¹³C NMR,FT-IR and GC-MS.The results confirmed that the compound was consistent with the target molecular structure.2)The corrosion inhibition performance of BAP solution to X70 steel was evaluated by weight loss method and electrochemical method.The weight loss method results showed that the corrosion inhibition efficiency of BAP in hydrochloric acid solution increased with the increase of BAP concentration and the temperature of the corrosion system.The adsorption of BAP on the surface of X70 steel conforms to the Langmuir adsorption mode of the monolayer.The?35?G⁰_{ad s} values during the adsorption process were between-28.47 k J mol^-1 and-35.27 k J mol^-1,which means that the corrosion inhibitor is adsorbed on the surface of the X70 steel sheet by corrosion inhibitor in the X70 steel surface is entropy increase process.The E_a value in the solution without corrosion inhibitor is larger than the E_a value containing the corrosion inhibitor,which further confirms that the adsorption of the corrosion inhibitor on the surface of the X70 steel sheet is chemical adsorption.The results of Tafel polarization curves show that the value of corrosion current density decreases with the increase of the concentration of BAP.The maximum corrosion potential difference was 14 m V,indicating that the corrosion inhibitor was a mixed type.Electrochemical impedance test results show that the charge transfer resistance increases with the increase of the concentration of the inhibitor,and the electric double layer capacitance decreases with the increase of the concentration of BAP,which indicates that the corrosion inhibitor adsorbed on the metal/solution interface formation of anticorrosion film to prevent the transfer of surface charge and mass loss of metal.The corrosion inhibition efficiency obtained by weight loss method and electrochemical method is in good consistency.3)The in situ polymerization corrosion resistance of BAP on X70 steel sheet was evaluated by weight loss method.The experimental results demonstrate that the corrosion inhibition efficiency of the corrosion inhibitor increases with the increase of the concentration of BAP.The anticorrosion efficiency of the BAP increases with the increase of the temperature of the corrosion system.The corrosion inhibition efficiency of the BAP increases with the increase of the soaking time.The anticorrosion efficiency of the BAP also increases with the increase of hydrochloric acid concentration.In the range of concentrations studied,?%?BAP in situ polymerization?>?%?PBAP-2?>?%?BAP?can be seen.In particular,at a low concentration,the difference between?%?BAP in situ polymerization?,?%?PBAP-2solution?and?%?BAP?is large,for example,at 90°C,10 ppm,?%?BAP?was51.97%,?%?PBAP-2?was 70.28%and?%?BAP in situ polymerization?was87.69%.However,the difference between?%?BAP in situ polymerization?,?%?PBAP-2?and?%?BAP?is continuously reduced with the increase of the corrosion inhibitor concentration,for example,at 90°C,70 ppm,the?%?BAP?was 95.72%,the?%?PBAP-2?was 97.57%and the?%?BAP in situ polymerization?was 98.86%.This reveals that through twice in situ polymerization can improve the corrosion efficiency of BAP,thereby reducing the amount of corrosion inhibitor.It was clear from the SEM image that the surface of the X70 steel had a filamentous of polymer film after the polymerizaion of acetylenic moiety in BAP molecule.The surface morphology of X70 steel was flower-like and became more dense after in situ polymerization of the aniline moiety on the surface of X70 steel.This dense layer can prevent the corrosion of X70 steel.The FT-IR analysis of the protective film on the steel sheet shows that the characteristic absorption peak of C?C at 2122.04 cm^-1disappears completely,indicating that BAP forms a PBAP-1 protective film on the structure),1463.13 cm^-1?stretching vibration of C=C of benzene ring?characteristic absorption peaks are indicated that the PBAP-2?a?corrosion inhibition film is formed by secondary in situ polymerization of the aniline moiety on the surface of X70 steel in the BAP molecule.4)The corrosion inhibition performance of BAP on X70 steel was studied by density functional theory?DFT?and molecular dynamics simulation?MD?.The parameters such as hardness???,softness?S?,energy gap??35?E?,dipole distance?m?and electron transfer number??35?N?were calculated.The calculated results show that BAP has good reactivity and corrosion inhibition performance.When adsorbed on the surface of iron,the BAP molecules are adsorbed on the Fe?100?plane in a nearly flat manner,confirming that there is a strong interaction between the corrosion inhibitor molecules and the Fe atoms,forming a layer of efficient corrosion inhibition film,reducing the dissolution of iron,showing its good corrosion inhibition performance.The results of the theoretical calculations are in good agreement with the results obtained by weight loss and electrochemical experiments.