Study On The Corrosion Inhibition Performance Of Levodopa Derivatives

At present,some natural extracts,drugs and amino acids are widely used as green corrosion inhibitors for metals due to their good water solubility,high efficiency,anticorrosion,health and environmental protection,and have become a research hotspot in the field of corrosion inhibition.Levodopa(L-DOPA)is a substance in the body and is mainly used for the treatment of Parkinson's disease.Levodopa is water-soluble,and contains multiple polar functional groups such as amino,carboxyl,and hydroxyl in its molecule,which helps to form a protective film on the metal surface and meets the structural requirements of corrosion inhibitors.Based on the low cytotoxicity of poly-(L-DOPA)and the better water solubility than monomers,the preparation of Poly-(L-DOPA)was studied by electrochemistry,SEM and CLSM.Poly-(L-DOPA)Corrosion inhibition effect on Q235 carbon steel in acid solution.The results showed that FTIR and UV-vis confirmed the synthesis of Poly-(L-DOPA),and the water solubility experiment showed that it is more water soluble than monomer.The electrochemical results show that in 1 M HCl,with the increase of Poly-(L-DOPA)concentration and the extension of immersion time,the corrosion inhibition efficiency increases.Poly-(L-DOPA)concentration is 300 mg/L,when time is 12 h,the highest corrosion inhibition efficiency is 97.8%.SEM and CLSM found that adding Poly-(L-DOPA),the surface roughness of Q235 carbon steel can be reduced from 968.7 nm to 318.0 nm,indicating that Poly-(L-DOPA)can exhibit a good inhibitory effect on the corrosion of carbon steel.Because of the good dispersibility of carbon dot materials,nitrogen-doped carbon dots(N-CDs)are synthesized by hydrothermal method using L-DOPA as the carbon source.TEM and UV-vis confirmed the successful synthesis of carbon dots.Electrochemical studies have shown that N-CDs has a significant corrosion inhibition effect,and the slow-release efficiency increases with the increase in concentration.When the concentration is 300 mg/L,the corrosion inhibition efficiency is as high as 97.9%.N-CDs conforms to Langmuir adsorption isotherm,which is a mixed physical and chemical adsorption.SEM and CLSM results showed that N-CDs inhibited the corrosion of Q235 carbon steel by acid solution,reduced damage and reduced roughness.P-L-dopa-SiO₂was synthesized by polymer growth grafting method,and the surface of SiO₂was chemically modified by levodopa polymerization.The results of FTIR,UV-vis and XRD confirmed the success of the synthesis without changing the crystalline structure of SiO₂.The electrochemical results show that the corrosion inhibition efficiency increases with the increase of the concentration of p-L-dopa-SiO₂.When the concentration of p-L-dopa-SiO₂is 500 mg/L,the corrosion inhibition efficiency can reach 85.9%.Adding p-L-dopa-SiO₂changes Polarization curve cathode and anode slope,the reduction reaction of cathode O₂or H⁺,and the oxidation reaction of anode metal are inhibited.It is a mixed inhibitor.SEM and CLSM found that p-L-dopa-SiO₂can reduce the surface roughness of carbon steel,showing a good inhibitory effect.