Synthesis And Performance Study Of Quercetin Derivatives As Corrosion Inhibitor On Aluminum

At present, the dosage of aluminum is the second largest in the world, and just behind steel. Aluminum is widly applied in industry and daily life. Due to the high development of aluminum and its alloy materials, the corresponding corrosion protection technologies are still in the exploring and perfection stage. Corrosion inhibitor has become one of the main means of corrosion protection because of its low dosage, simple operation, and economic security. With the continuous development of modern civilization, the human's environmental protection consciousness is gradually strengthened; developing low toxic, environmental friendly, efficient corrosion inhibitors will become a new research direction in the field of metal corrosion and protection. This paper use the natural compound quercetin as raw material, by changing the functional group and change its molecular polarity, to solve the problems of water solubility, and applied to the corrosion and protection of aluminum and magnesium, examine its corrosion performance.This essay includes the following three sections:(1) Explored the synthetic methods of quercetin-7-sodium sulfate (QS) and quercetin-7-acetate (QA). Then the reaction conditions for the synthesis were optimized through orthogonal test by exploring the material ratio, reaction temperature and reaction time. The structure of the products was characterized by NMR and IR.(2) Set up the standard curve of quercetin (QU), quercetin-7-sodium sulfate (QS), quercetin-7-acetate (QA), and measured the concentration of their saturated solution concentration. Results showed that the solubility of QS and QA were all have a large increase, they were increased 188.04 and 110.9 times respectively.(3) Using the method of weight loss, potentiodynamic polarization curve and EIS to study the corrosion performance of aluminum in 1 mol/L HC1 solution. Results showed that the two compounds were all have good anticorrosive property, and they were cathode inhibited type corrosion inhibitors. FT-IR and SEM confirmed that compounds strongly adsorbed onto the aluminum surface, blocking its active sites and preventing it from being corroded. The adsorption of the inhibitor on the aluminum surface followed the Langmuir adsorption isotherm, and this process is spontaneous. According to Arrhenius equation to calculate the activation energy of the corrosion, the results showed that the energy is increased with the addition of corrosion inhibitors, and it means that energy barrier of corrosion reaction is increased.(4) In order to expand the application scope, the corrosion performance of QS and QA for magnesium alloy in ASTM D384-87 corrosion solution was studied. Test results showed that the inhibition efficiency increases with the increase of the inhibitor concentration, the best efficiency can be more than 90%, at the same time, the inhibition efficiency is not affected by temperature. Then inspected the adsorption behavior of these compounds, found that it obeyed Langmuir's adsorption isotherm, and calculated the corresponding dynamic parameters.