Research On The Corrosion Inhibition Of Performance Pyridyl Ionic Liquids For N80 Steel In Acid Solution

Traditional corrosion inhibitors have problems such as low solubility,high toxicity,poor stability,poor biodegradability,and cost constraints during chemical pickling,which will cause serious disadvantage to the environment and ecology.Therefore,the development of green corrosion inhibitors that do not have a damaging effect on the environment has become a hot spot for corrosion inhibitor research.Ionic liquids have the characteristics of good stability,design,and environmental protection,it is one of the research hotspots of environment-friendly corrosion inhibitors.In my research,four different pyridyl ionic liquids were selected,named N-octyl-4-methylpyridine bromide?O4MePyBr?,N-butyl-4-methylpyridine bromide?B4MePyBr?,and N-butyl-4-methylpyridine tetrafluoroborate?B4MePyBF₄?,N-butyl-4-methylpyridine hexafluorophosphate?B4MePyPF₆?,and traditional dimethyl sulfate pyridinium quaternary ammonium salt corrosion inhibitors.Electrochemical method,weight loss experiment,scanning electron microscope test?SEM?,atomic force microscope?AFM?,quantum chemical calculation and other methods have systematically researched their corrosion inhibition behavior of N80 steel in 1M HCl solution at 298K.The main research contents and conclusions are as follows:?1?The results of electrochemical impedance spectroscopy show that with the increase of the concentration of the inhibitor,the charge transfer resistance R_ct of the electrode increases,the electric double layer capacitance C_dll decreases,and the corrosion inhibition efficiency increases.Because more and more inhibitor molecules have replaced the adsorption of water molecules on the electrode surface,the resistance of charge transfer is gradually increased,and the corrosion of metals is suppressed.?2?The polarization curve results showed that with the increase of the concentration of the corrosion inhibitor,the E_corr shifts positively,the I_corr decreases significantly,and the corrosion inhibition efficiency increases.They did not change the reaction mechanism of cathode and anode.The five inhibitors are all mixed inhibitors.?3?The results of weight loss experiments and surface morphological characterization showed that with the increase of the concentration of the inhibitor,the corrosion rate gradually decreases and the corrosion inhibition efficiency gradually increases.The inhibitors can effectively adsorb on the surface of the sample,which can mitigate the corrosion of N80 steel to a certain extent.?4?The results of adsorption thermodynamic calculations showed that the adsorption of the five corrosion inhibitors in this system conforms to the Langmuir adsorption isotherm model.The?G⁰_adsds values are all negative,so they are all spontaneous processes.And they are all mixed adsorption that physical adsorption and chemical adsorption coexist except O4MePyBr.?5?Quantum chemical calculations showed that the corrosion inhibition performance of ILS is closely related to its structure.Both the?E value and the?value at the optimal molecular configuration will affect the corrosion inhibition performance of ILS.ILS and Fe surface electrons form feedback bond and coordination bond,then forming an adsorption film on the surface of N80 steel.?6?The order of the corrosion inhibition performance of the anions on the ionic liquid corrosion inhibitor is B4MePyBF₄?>B4MePyBr?>B4MePyPF₆?.The order of the chain length of the alkyl chain for the ionic liquid corrosion inhibitor is O4MePyBr>B4MePyBr.And the four ionic liquid corrosion inhibitors researched are better than the traditional dimethyl sulfate pyridinium quaternary ammonium salt inhibitors.