Corrosion Behavior Of Acrylamide Polymer Modified By Cyclodextrin On L485 Steel

The corrosion of oil pipeline and equipment has been found widely exists in the process of oil-gas development, as the corrosion of steel could lead to safe and technological problems. Thereby it is particularly important to inverstigate the corrosion mechanism and research inhibition methods to prevent the steel corrosion for oil-gas and petrochemical industry. As the superior characteristics of inhibitor such as add lower dosage, effective, it is found widely used in various fields. The inhibiting performance of β-Cyclodextrin-modified acrylamide polymer (HCMPAM) on L485steel in0.5mol/L H2SO4solution has been investigated using electrochemical impedance spectroscopy (EIS), Tafel polarization, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and molecular dynamics (MD) simulation methods. And the adsorption isotherm model of HCMPAM on L485steel, thermodynamic and kinetic parameters have been analyzed. Those results obtained can provide a theoretical basis for the practical application and feasibility of HCMPAM. The main research contents are as following:(1) The inhibiting of β-clodextrin (β-CD) and HCMPAM for L485steel in0.5mol/L H2SO4at different temperatures and concentrations have been investigated by EIS and Tafel methods. The results obtained indicate that: compared with the blank H2SO4solution, the charge transfer resistance (Rct) increases, the double layer capacitance (Cdl) and corrosion current density (icorr) decreases after the adding of β-CD and HCMPAM, which indicates that HCMPAM reduce the corrosion process of L485steel in medium through the adsorption of inhibitor on metal surface and does not alter the corrosion mechanism. In addition, HCMPAM copolymer acts as mixed-type inhibitor, the inhibition efficiency increases with the increase of HCMPAM concentration and decreases with the increase of temperature, the order of inhibition efficiency is:HCMPAM> β-CD, while P-CD has a poor inhibition performance for L485steel.(2) The adsorption isotherm model of HCMPM on L485steel, thermodynamic and kinetic parameters are analyzed by Tafel polarization. The results obtained indicate that:the corrosion process of L485steel in H2SO4is endothermic, the increase of temperature could accelerate the corrosion of steel. Compared with the blank solution, the values of Ea and AH*increase to a greater extent in the presence of HCMPAM, this means that the energy barrier of the corrosion reaction increases with the adding of HCMPAM. Meanwhile the adsorption of HCMPAM on L485steel is confirmed to obey the Langmuir isotherm and governed by chemisorptions. And the adsorption process of HCMPAM on L485steel is exothermic, thereby the increase of temperature could restrain the adsorption of HCMPAM on L485steel surface.(3) The SEM and EDS results indicate that:compared with the blank solution, the surface of L485steel shows uniform and no significant corrosion after the adding of HCMPAM. In addition, the EDS results reveal that the content of Fe element rises, the content of O element decreases, and there is N element on L485surface in HCMPAM solution. Thereby HCMPAM can form the protective film on L485steel surface to impede the contact of L485steel with corrosion medium.(4) MD research indicates that:HCMPAM can parallel and rapidly adsorb on Fe surface. HCMPAM can adsorb on metal surface through bonding interaction and non-bonding interaction combined resulting from N, O atoms in HCMPAM molecular and Fe atom.