Study On Modification Of Aspartic Acid Corrosion Inhibitors By Aldehyde Synergism And Their Corrosion Protection For Carbon Steel

Carbon steel surfaces of industrial equipment are prone to corrosion and scale inhibition after operating for a period of time.To solve this problem,the most commonly used and effective method is to remove dirt by acid pickling.However,acids have a corrosive effect on metals,especially inorganic acids.The most commonly used method is to add acid pickling corrosion inhibitors.This method can not only ensure the ability of acid pickling,but also slow down the corrosion of carbon steel.Natural acid pickling corrosion inhibitors have received considerable attention due to their applicability to natural ecosystems.Among them,aspartic acid(ASP)type corrosion inhibitors have been the focus of research in recent years and are expected to replace traditional inorganic corrosion inhibitors that are harmful to the environment.However,the effect of this corrosion inhibitor is not ideal,and most researchers have conducted synergistic and coordination derivatization modifications to enhance its corrosion inhibition performance.However,derivatization of regulatory sites is often complex and costly,which is not conducive to large-scale industrial applications.This paper systematically investigated the corrosion inhibition behavior of ASP type inhibitors on carbon steel,and analyzed the reasons for their poor corrosion inhibition effect on carbon steel based on electronic and three-dimensional effects;" one-pot aqueous-phase reaction method " was used to modify ASP type corrosion inhibitors with aldehyde synergistic effect.Then,the sensitivity of modified L-aspartic acid methyl ester salt(L-ASP methyl ester salt)and polyaspartic acid(PASP)to the temperature of corrosive media was investigated,and the corrosion inhibition mechanisms of both were studied.Specific studies include the following.Chapter 1.Introduction.The pickling and corrosion prevention of mechanical equipment,the principle and synergistic effect of corrosion inhibitors,the classification and modification progress of ASP-type inhibitors are summarized.The current research status of ASP type of corrosion inhibitors in terms of high-performance,structure-activity correlation and synergistic corrosion inhibition principles was introduced.Challenges of ASP-type inhibitors were analyzed,and the research content and innovation points of this paper were proposed.Chapter 2.Establish experimental methods.Q235B carbon steel was selected as the research object to prepare a simulated industrial pickling corrosion solution.Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and field emission scanning electron microscopy(SEM)were used to observe the structure and morphology of the corrosion interface.The corrosion inhibition performance of ASP type corrosion inhibitors on carbon steel was studied by weight loss method,electrochemical polarization curve,and impedance spectroscopy.Chapter 3.The corrosion inhibition performance of ASP-type inhibitors on carbon steel was investigated.The corrosion inhibition properties of L-aspartic acids which might affect by different electronic and steric hindrance effects on carbon steel in 0.5 mol/L H2SO4 were compared and studied by using weight loss method,and the mechanism of their interaction with iron at the corrosion interface was preliminarily analyzed from the perspective of structureeffect correlation.The results provide experimental reference and theoretical guidance for the subsequent synergistic modification by introducing aldehyde.Chapter 4.The corrosion inhibition performance of glutaraldehyde modified methyl Laspartate salt on sulfuric acid corrosion of carbon steel was studied.Firstly,a " one-pot aqueousphase reaction method " process for aldehyde modified ASP molecules was established to prepare a modified corrosion inhibitor mother liquor of methyl L-aspartate salt,and then the weight loss method was used to explore the optimal ratio of corrosion inhibitors and their sensitivity to temperature;Then,combined with FTIR,electrochemical method,SEM and other analytical methods,the corrosion inhibition performance of methyl L-aspartate modified by glutaraldehyde synergism on carbon steel was studied,and the corrosion inhibition principle was analyzed.Chapter 5.The corrosion inhibition performance of GA modified PASP on carbon steel in sulfuric acid was studied.According to the methods in Chapter 4,the optimal process parameters for the combination of PASP and GA were studied,and the effects of electronic and steric effects on the corrosion inhibition performance of the obtained GA modified PASP were discussed as well as the related corrosion inhibition principle.