Synthesis And Evaluation Of The Multifunctional Corrosion Inhibitiors By Imidazoline Guanidine Derivatives

In this work,three novel imidazoline guanidine derivatives(IGs)were synthesized.The corrosion inhibitors obtained from caprylic acid,lauric acid and oleic acid named CIG,LIG and OIG,respectively.The IGs were used as corrosion and microbial inhibitors.The new imidazoline guanidine derivatives(IGs)were investigated as corrosion inhibitors of mild steel in 1.0 mol/L HCl.The results showed that the IGs are mixed-type inhibitors and their inhibition efficiency increases with the increasing addition of each inhibitor and the growing longer of side alkyl chain in IGs.The maximum efficiency of CIG,LIG and OIG,all obtained at an inhibitor addition of 320 ppm were 95.07 %,97.22 % and 97.29 %,respectively.The adsorption of IGs on mild steel surface follows Langmuir isotherm model,and the adsorption process is a spontaneous process,including physical adsorption and chemical adsorption.It is worthwhile to note that the inhibition efficiency decreases with the elevated temperature.SEM and XPS analysis confirmed the formation of protective layer on the mild steel surface.The IGs were investigated as corrosion inhibitors of stainless steel in 4.0 mol/L HCl.The experimental results showed that IGs acted as an efficient inhibitor against the stainless steel corrosion,and their inhibition efficiency increased with the inhibitor concentration and IGs were mixed-type inhibitors.The maximum efficiency of CIG,LIG and OIG,all obtained at an inhibitor addition of 100 ppm were 94.55 %,95.09 % and 95.69 %,respectively.The adsorption of IGs on the stainless steel surface in hydrochloric acid solution followed the Langmuir adsorption isotherm.Adsorption of the inhibitors on stainless steel surface involved both physical and chemical adsorption.The corrosion inhibition performance of OIG in 3.5 % NaCl system shows that the inhibition efficiency of OIG is 69.23% when the concentration of OIG is 8 ppm,and it is a mixed-type inhibitors.The IGs were investigated as bactericide in standard salty water solution.The results showed that the bactericidal rate of LIG was the best,and the bactericidal power was 99.78%,which was higher than CIG and OIG.The mechanism of the antibacterial mechanism is that the IGs is adsorbed on the surface of the cell wall by electrostatic attraction,and then the permeability of the cell membrane is changed,and the nutrients are prevented from entering the bacteria body.In conclusion,the three new imidazoline inhibitors have good corrosion inhibition and bactericidal performance,which have high research value and wide application prospect.