Study On The Synthesis Of Ethanolamine Phosphate And Its Corrosion Inhibition Mechanism

In glycol-water-based coolants,because ethylene glycol forms acidic substances to corrode metal pipes at high temperatures,adding corrosion inhibitors to the coolant is a commonly used method to prevent metal corrosion.Therefore,studying the corrosion inhibition performance and corrosion inhibition mechanism of corrosion inhibitors is of great significance for the formation of a coolant system with independent intellectual property rights in my country.In this paper,single-factor experiment method and three-factor three-level orthogonal experiment are used to optimize the synthesis process of ethanolamine phosphate;on this basis,the effect of concentration and temperature on corrosion inhibition performance is studied by weightlessness method;then,using electrochemical test technology,the research The electrochemical behavior of ethanolamine phosphate was discussed.Finally,the microscopic molecular mechanism of ethanolamine phosphate was explored based on quantum chemical calculations and molecular dynamics simulations to reveal its corrosion inhibition mechanism.The results of the study indicate that the three-factor three-level orthogonal test is designed based on the ratio of reactants(A),reaction time(B)and solvent consumption(C).The optimal reaction condition is A2B2C3.The product is analyzed by infrared spectroscopy.Elemental analysis and nuclear magnetic testing can determine that the synthesized product is ethanolamine phosphate.In the glycol-water-based solution,the concentration and temperature of ethanolamine phosphate gradually increase,and the corrosion inhibition rate gradually increases,while the corrosion rate of cast iron and carbon steel is suppressed and gradually decreases.The maximum corrosion inhibition rate can reach 66%;The surface of the metal added with ethanolamine phosphate is relatively flat,and the elements C,N,O,P are present on the surface of carbon steel and cast iron,indicating that ethanolamine phosphate plays a film-forming role on the metal surface;ethanolamine phosphate is used on carbon steel and cast iron The adsorption model on the surface conforms to the Langmuir adsorption configuration,and it is a mixed adsorption mainly based on chemical adsorption and supplemented by physical adsorption;the adsorption free energy ?G is-33.25kJ/mol and-34.69kJ/mol,respectively,and the addition of ethanolamine phosphate The activation energy of the corrosion reaction is increased,and the occurrence of the corrosion reaction is suppressed,thereby effectively protecting the metal.In the glycol-water-based solution,the addition of ethanolamine phosphate can promote the passivation of the metal surface and act as an anode-type corrosion inhibitor.There are two time constants in the impedance spectroscopy of carbon steel and cast iron,which indicates that there are two reaction processes,which are the formation process and the destruction process of the corrosion inhibitor film on the corrosion medium and the metal surface.With the increase of ethanolamine phosphate concentration and soaking time,the reaction resistance gradually increased,thereby slowing the electrochemical corrosion of metals.Using modern computer simulation technology to perform quantum chemical calculations on ethanolamine phosphate,the distribution of HOMO and LUMO energy orbits is mainly delocalized near the two groups-NH2 and-P=O,which is the same as the result of the molecular electrostatic potential;To calculate the Fukui index,the higher Fukui(+)value is P(1)and O(3),and the higher Fukui(-)value is N(8),the conclusion is consistent with the frontline orbit theory;ethanolamine When phosphate ester is adsorbed on the metal surface,it is almost parallel to the metal surface,which maximizes the interaction between the ethanolamine phosphate ester and the Fe atom,provides the maximum surface protection,and therefore has a high corrosion inhibition efficiency.