Study On The Performance And Mechanism Of Compounded Corrosion Inhibitor Based On Unsaturated Film-forming Amine

Corrosion of industrial equipment causes a lot of economic losses and environmental pollution every year.Adding corrosion inhibitor to equipment is a convenient,fast,safe and effective protection measure.In order to adapt to the concept of green development,attention should be paid to safety and environmental protection when selecting and compounding corrosion inhibitors.N-oleyl-1,3-propanediamine(NOPDA),which contains one unsaturated double bond and two amino groups,is an excellent corrosion inhibitor component.In this study,diethylaminoethanol(DEAE),emulsifiers(HT),surfactants(ST)and dispersant(HS)were selected to compound it to improve its fluidity and water solubility.Orthogonal test was used to screen out the best ratio,and finally two corrosion inhibitors FFA1 and FFA2 with strong fluidity,good water solubility and good effect were prepared.Through static weight loss experiment(WL),electrochemical impedance spectroscopy(EIS),contact angle,Scanning electron microscopy(SEM),atomic force microscopy(AFM)and X-ray photoelectron spectroscopy(XPS)testing and characterization,the corrosion inhibition performance was investigated and the corrosion inhibition mechanism was explored.The results show that the best proportion of FFA1 was NOPDA:DEAE:ST:ST=2.5:15:8:5(wt%),and in such a proportion the corrosion inhibition efficiency was obtained to be 92.1%.The?of FFA1 increased with the increase of temperature,which indicated that the adsorption process was endothermic.?increased with the increase of the dosage,and when the concentration reached 5 g/L,the phenomenon of extreme concentration appeared.The results of WL showed that the adsorption process of FFA1 conformed to Langmuir model.The adsorption was a spontaneous endothermic process,involving both physical and chemical adsorption mechanisms.EIS results showed that FFA1 inhibited corrosion by increasing the resistance of charge transfer.The IE of FFA1was 88.86%at 25?.The results of contact angle test showed that FFA1 formed a uniform hydrophobic film on the surface of the test piece.The average contact angle of FFA1 was87.2°.SEM images and AFM results further confirmed that FFA1 formulations exhibited good corrosion inhibition performance.The surface roughness of carbon steel samples with FFA1 corrosion inhibitor decreased by 86.4%.X-ray photoelectron spectroscopy(XPS)was used to analyze the function mechanisms of FFA1.The results showed that inhibition mechanisms mainly involved the following three aspects:first,physical adsorption occurred between NH₃⁺and Cl^-adsorbed on the sample surface;second,the nitrogen atom on the amino group and the unsaturated double bond formed coordination bonds with Fe,resulting in chemical adsorption;third,hydrogen bonds were formed between the hydrogen on the amino group and the oxides formed on the surface of carbon steel.The best proportion of FFA2 was NOPDA:DEAE:HT:ST:HS=2.5:15:10:6:5(wt%),and in such a proportion the corrosion inhibition efficiency was obtained to be 94.1%.The?of FFA1 increased with the increase of temperature,which indicated that the adsorption process was endothermic.?increased with the increase of the dosage,and when the concentration reached 5 g/L,the phenomenon of extreme concentration appeared.The results of WL showed that the adsorption process of FFA2 conformed to Langmuir model.The adsorption was a spontaneous endothermic process,involving both physical and chemical adsorption mechanisms.FFA2 inhibited corrosion by increasing the resistance of charge transfer.The IE of FFA2 was 89.01%at 25?,which was better than FFA1.The results of contact angle test showed that FFA2 formed a uniform hydrophobic film on the surface of the test piece.The average contact angle of FFA2 was 94.9°,which was significantly better than FFA1.SEM images and AFM results further confirmed that FFA2 formulations exhibited good corrosion inhibition performance.The surface roughness of carbon steel samples with FFA2 corrosion inhibitor decreased by 87.2%,which was slightly larger than FFA1.X-ray photoelectron spectroscopy(XPS)was used to analyze the function mechanisms of FFA2.The results showed that inhibition mechanisms mainly involved the following three aspects:first,physical adsorption occurred between NH₃⁺and Cl^-adsorbed on the sample surface;second,the nitrogen atom on the amino group,the unsaturated double bond and the sulfonic acid group contained in FFA2 formed coordination bonds with Fe,resulting in chemical adsorption;third,hydrogen bonds were formed between the hydrogen on the amino group and the oxides formed on the surface of carbon steel.