Raman Spectroscopy And Electrochemical Study On The Adsorption Behavior Of Phytic Acid Compounds On Copper Surface

As a green chemical way，we once introduced a kind of green molecules, phyticacid (PA), which could be used as the corrosion inhibitors in salt solution. PA containssix phosphate groups which can interact with the metal ions. The most attractiveadvantage of PA is its availability as a naturally polyphosphorylated carbohydrate,which widely occurs in beans, brownirce，corn，sesame seeds, and wheat bran. Theuse of PA as the cleansing agent, water treatment agent, food additive and cosmeticadditive proves that it is non-toxic to human and "green" to the environment。Copperand its alloys have been used in various ways of industrial and microelectronicapplications due to its good thermal, electrical conductivity, mechanical workability,and relatively noble properties. However, copper and its alloys easily suffer fromsevere corrosion, especially in the aggressive environment, con-taining CN、NH+、CI-、NO3’ ions. As a green chemical way, we once introduced a kind of greenmolecules, phytic acid (PA) and PA micelle, which could be used as the corrosioninhibitors in corrosive solution. In this work，we used electrochemical impedancespectroscopy (EIS) and electrochemical polarization to investigate the corrosioninhibition behavior of PA SAMs and PA micelle for copper in aggressive solution.Electrochemical impedance spectroscopy (EIS) technique，a non-destructive, sensitiveand informative method has been extensively used as the evaluation of coatings forcorrosion inhibition. The electrochemical polarization can provide the corrosion ratesfrom linear polairzation and determine the eiffciency of corrosion inhibitor.Self-assembled monolayers (SAMs) technique is regarded as a reasonable method tocontrollably construct an orderly uniform layers. SAMs can provide a ideal model forinvestigating the relationship between anti-corrosion and adsorption structure ofinhibitors monolayers on the copper surface, SERS technique was used to provideinsight into the interaction manner of the PA molecule and the copper surface. Theadsorption of PA SAMs on copper surface followed Langmuir isotherm and revealeda chemical adsorption on the copper surface. Meanwhile, the synergistic effect of I*was used to improve the corrosion inhibition of PA. At last, the corrosion inhibition behavior of PA micelle was also studied. At last, the corrosion inhibition behavior ofPA micelle was introduced, by both the electrochemical methods and Ramanspectroscopy.1.In this chapter, the adsorption of phytic acid (PA) on copper was investigated usingelectrochemical impedance spectroscopy (EIS), electrochemical polairzationmeasurement and surface-enhanced Raman scattering (SERS) spectroscopy.Electrochemical results indicated that inhibition eiffciency of PA film for copper fromcorrosion in3wt%NaCl solution was beyond80%at an optimum self-assemblyconcentration of0,1mM for6h. Electrochemical polarization indicated that PASAMs functioned as a cathodic inhibitor. In addition, Raman Studies showed that PASAMs adsorbed on the copper surface formed via P-0groups. Finally, the value ofAGads (-39.96kJ1mol") was close to-40kj mol’1, suggesting that the adsorption of PAon the copper surface was the chemical adsorption.2.In this chapter, the adsorption behavior of phytic acid (PA) self-assembledmonolayers (SAMs) at the copper surface, and its corrosion inhibition mechanism in0.5M H2SO4solution，was studied by using electrochemical impedance spectroscopy(EIS), potentiodynamic polarization and surface-enhanced Raman scatteringspectroscopy (SERS). Raman studies showed that PA SAMs on the copper surfaceformed via P-0groups and the cyclohexyl ring. The adsorption of PA SAMs oncopper surface followed Langmuir isotherm and revealed a chemical adsorption onthe copper surface. The presence of I-ions with PA SAMs at the copper surfaceshowed a synergistic effect and increased the inhibition efficiency.3.In the last two chapters, the corrosion inhibition behavior of PA SAMs was investedin both saline and acidic solutions. According the references, the PA micelle wasformed by heating the PA solutions in different concentrations. So in this chapter, thecorrosion inhibition behavior of PA micelle was introduced, by both theelectrochemical methods and Raman spectroscopy. In addition, the different conditions for the formation of PA were studied. The result showed that the PAmicelle also had a better corrosion inhibition behavior.