Study On The Corrosion Inhibition Effect Of Guar Gum Derivatives On J55 Steel

Carbon steel is widely used in various fields of petrochemical industry and other applications,but carbon steel has bad corrosion resistance and often comes into contact with various corrosive media during use,especially with acidic media,this has a great impact on the life expectancy of carbon steel.Carbon steel’s corrosion also cause major economic losses,and it maybe happened to accidents that threaten people’s lives.Therefore,the corrosion and protection of carbon steel is an important concern that affects the development of the petroleum and chemical industry.The application of corrosion inhibitors is currently the most cost-effective means of dealing with carbon steel corrosion.The corrosion inhibitors used at this stage are mainly organic corrosion inhibitors,because the organic molecules may contain o,N,S and other atoms with unshared pair electrons and π bonds.Such organic molecules can be empty orbital which inferact with carbon steel surface.The d orbital acts to form a protective film to achieve corrosion protection.Glue extracted from natural plants is one of them.Gum contains a large amount of O atoms and has received a lot of attention and been widely studied.At the same time,the use of gums as corrosion inhibitors can effectively improve the utilization rate of natural plants.This paper uses of guar gum and four monomers:methyl methacrylate(MMA),vinyl acetate(VAC),ethyl acrylate(EA)and 2-acrylamido-2-methyl-1-propane sulfonic acid(AMPS)is used as the raw materials,and these four monomers are grafted onto guar gum by chemical methods to synthesize guar gum derivatives as corrosion inhibitors,marked as G-M,G-V,G-E,G-A respectively,and 3.5%NaCl saturated CO2 solution is selected as the corrosion medium,and J55 steel is the corrosion metal.Comparing the corrosion inhibition performance of these four kinds of guar gum derivatives on carbon steel,the results demonstrated that:(1)By designing the synthetic route from the reference and synthesizing four kinds of guar gum derivatives,the four derivatives were characterized by infrared spectroscopy.The results showed that the corresponding guar gum derivatives were successfully synthesized.(2)The corrosion inhibition effect of four kinds of guar gum derivatives on J55 carbon steel under 3.5%NaCl saturated CO2 solution was evaluated by laboratory method such as weight loss method and electrochemical method.The results showed that the inhibition efficiency of guar gum derivatives increased with the increase of corrosion inhibitors concentration,and gradually decreased with the increase of temperature.The order of corrosion inhibition performance from good to bad is G-A,G-V,G-E,G-M,the best is guar gum grafted 2-acrylamido-2-methylpropanesulfonic acid(G-A).The results of electrochemical impedance spectroscopy showed that these four guar gum derivatives had no effect on the mechanism of metal corrosion,mainly by controlling the charge transfer process to reduce the occurrence of corrosion.The polarization curve test results show that the three guar gum derivative corrosion inhibitors of G-M,G-V and G-A are mixed corrosion inhibitors,while the corrosion inhibitor of G-E is an anode type corrosion inhibitor,and the corrosion current of the corrosion inhibitor decreases with the increase of the addition amount.(3)Scanning electron microscopy SEM and EDS spectra were used to observe the surface morphology of the steel surface and analyze the surface composition of the steel.The results show that the guar gum derivative can effectively reduce the corrosion of J55 steel surface,and the corrosion inhibition effect for J55 steel by G-V and G-A is better,and the effect of G-M and G-E is not good.This maybe due to the adsorption of guar gum derivative forms a dense and stable organic protective film on the steel surface to reduce the corrosion process.Using SECM to observe the microscopic morphology of the steel surface,the results show that the guar gum derivative can effectively reduce the current value of the J55 steel surface and reduce the corrosion,which maybe mainly through the formation of a protective film with poor conductivity to make the metal surface.The conductivity changes,thereby delaying the occurrence of the corrosion process,which is consistent with the results of the SEM.(4)Using the adsorption model to fit the electrochemical test results and the adsorption thermodynamies ealeulations showed that the adsorption of guar gum derivatives on the surface of J55 steel according to Langmiur adsorption isotherm,and the adsorption mode was mainly physical adsorption.(5)The quantum chemistry theory was used to study the adsorption mechanism of guar gum derivative corrosion inhibitor molecules on the metal surface.From the calculated quantum chemical parameters,the energy of G-A in these four guar gum derivative corrosion inhibitors can be known,its gap value is the lowest,the hardness is the smallest,the softness is the largest,and the electronegativity is the largest.Therefore,among the four guar gum derivatives,G-A has high molecular activity and the highest inhibition efficiency.So,in theory,G-A should be the best eorrosion inhibition performance of the four guar gum derivative corrosion inhibitors in theory,and this conclusion is the same as the results obtained in the above experiments.