Synthesis And Corrosion Inhibition Properties Of ?-Amino Alcohol Inhibitors

Mild steel,exhibiting excellent mechanical properties,is widely used in various aspects such as factory equipment and oil field exploration.However,mild steel is an active material with poor corrosion resistance,especially in descaling and oilfield extraction.Mild steel inevitably closely contact with acidic solutions,which usually aggravates metal corrosion.The most common way to avoid metal corrosion is to add corrosion inhibitors.The research and development of low-dosage,high-efficiency and environmental protection corrosion inhibitors has always been sought by chemistsIn this paper,three new ?-amino alcohol compounds were,named as DS,TDB,DQ,synthesized by the reaction of ethylene glycol diglycidyl ether with 2-thiophene methylamine,4-(2-aminoethyl)benzenesulfonamide,and 2-mercaptoethylamine under mild conditions,respectively.The corrosion inhibition properties of these ?-amino alcohol compounds for mild steel in 0.5 M H2SO4 solution were studied by weight loss and electrochemical method.Scanning electron microscope,X-ray photoelectron spectroscopy,thermodynamic analysis,and theoretical calculation were used to study the mechanism of the inhibitors.The specific research content and results are as follows:The results of weight loss and electrochemical tests show that several corrosion inhibitors exhibit good inhibition efficiency on mild steel in 0.5 M H2SO4 solution.Among them,corrosion inhibition efficiency of DS on mild steel is 97.1%at 50 mg/L.While the corrosion efficiency reached more than 92%(weight loss method)when TDB and DQ at concentrations of 10 mg/L and 5 mg/L,respectively.It indicated that these inhibitors have the advantage of low amount and high efficiency compared with the corrosion inhibitors reported in the literatureElectrochemical tests showed that three corrosion inhibitors DS,TDB and DQ were all mixed corrosion inhibitors.The results of thermodynamic research indicated that the three ?-amino alcohol corrosion inhibitor molecules form protective films on the surface of mild steel by spontaneous adsorption,which reduced the direct contact between mild steel and aggressive media to inhibit the corrosion of mild steel.The adsorption behavior of the inhibitor molecules on the surface of mild steel was consistent with the Languirm monolayer adsorption model,which includes both physical and chemical adsorption.The results of XPS also showed that inhibitor molecules adsorbed on the surface of mild steel to form the effective protective film.It can be seen from the SEM research that the corrosion inhibitor significantly reduced the degree of corrosion of the mild steel surface compared with the blank experimentThe quantum chemical calculation method was used to optimize the structure of the inhibitor molecule It can be seen that the structure of the inhibitor molecules has a certain linear structure,which provides an advantageous structure for the adsorption of more molecules on the surface of mild steel.And the electron cloud density is mainly concentrated on aromatic rings and heteroatoms such as O,N,and S,the former can form a protective film on the surface of carbon steel by ?-? conjugation,and the latter can provide lone pair electrons to form coordination bonds to the empty orbits of metal atoms on the surface of mild steel.