Study On Corrosion Inhibition Performance Of Ternary Complexes Of Rare Earth And Transition Metal

In industry,pickling is one of the most effective methods to remove scale and rust,in which sulfuric acid and hydrochloric acid are the most widely used pickling agents.Due to the strong corrosiveness of pickling agents,rust and scale removal will also produce strong corrosion to metals,resulting in huge economic losses and harm.Among all kinds of anti-corrosion measures,adding corrosion inhibitor is an economical and effective method.The molecular structure of commonly used corrosion inhibitors generally contains N,O,P,S and other heteroatoms,and they are also common metal complex ligands.In recent years,it has been reported that metal complexes have better corrosion inhibition performance than their ligands.However,the reports in the literature are all binary metal complexes,and ternary complexes of rare earths and transition metals have been synthesized in this paper.compared with binary complexes,ternary complexes have larger molecular weight and can provide larger coverage area on the metal surface.so as to further improve the corrosion inhibition performance of metal complexes.The main results are as follows:(1)The ternary complex of cobalt was synthesized by using 1,10-phenanthroline(phen),p-hydroxybenzoic acid(phba)as ligand.The corrosion inhibition performance of the complex for P110 low carbon steel in acidic medium was studied by Co-phen-phba,.The results show that the inhibition efficiency of the complex increases with the increase of concentration and decreases with the increase of temperature at 298.15 K.According to the thermodynamic data,the complex can be spontaneously adsorbed on the surface of carbon steel and follow the Langmuir isothermal adsorption model.(2)Nickel ternary complex was synthesized by using 2,2-bipyridine(bipy),benzoic acid(ba)as ligand.The corrosion inhibition performance of the complex for P110 low carbon steel in acidic medium was studied by Ni-bipy-ba,.The electrochemical test results show that the complex is a mixed corrosion inhibitor,and the inhibition efficiency reaches88.41% when the concentration is 400 ppm.The Gibbs free energy of the complex is-25.540 k J/mol,indicating that the complex can be spontaneously adsorbed on the surface of carbon steel,and there are both physical and chemical adsorption on the surface of carbon steel.(3)The rare earth lanthanum ternary complex: La-phen-sa,was synthesized by using1,10-phenanthroline(phen),succinic acid(sa)as ligand.The corrosion inhibition performance of the complex for P110 low carbon steel in acidic medium was studied.The results show that the corrosion inhibition performance of the complex is better than that of the ligand.The inhibition efficiency of the complex is related to the concentration and temperature.When the concentration is 400 ppm,the inhibition efficiency reaches 96.27%.At high temperature,the complex can still show good corrosion inhibition performance.