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| SAMS OF DODECYL MERCAPTAN AND ITS CORROSION PROTECTION ON IRON SURFACE |
| WANG Jing, LI Degang, YU Xianjin, DONG Yunhui, ZHANG Lipeng |
| School of Chemical Engineering, Shandong University of Technology,Zibo 255049 |
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Abstract Self-assembled monolayers (SAMs) of n-and t-dodecyl mercaptan were prepared on iron surface by self-assembly methods. From the results of FT-IR, it can be found that both the n-and t-dodecyl mercaptan can self-assemble on the surface of iron. Then the electrochemical impedance spectroscopy (EIS) and the Tafel polarization curves were performed to characterize the anticorrosion capability of the SAMs in 0.5 mol/L NaCl solution. The general equivalent circuits for the n-and t-dodecyl mercaptan SAMs were established. Based on the results of the EIS, proper equivalent circuit was chosen to fit the Nyquist impedance plots. The inhibition efficiency (IE) of the SAMs on iron corrosion have been calculated according to the fitted results and the Tafel polarization curves. When the iron electrode self-assembled in the n-and t-dodecyl mercaptan for 3h, the IE of the SAMs can reach about 89% and 80% respectively. Comparing with the SAMs of the t-dodecyl mercaptan, the SAMs of n-dodecyl mercaptan have more effective corrosion inhibition for iron as indicated by the high charge-transfer resistance shown in EIS and the positive corrosion potential in the Tafel polarization curves. It is quite possible that the steric hindrance of t-dodecyl mercaptan is bigger than that of n-dodecyl mercaptan. Therefore, it is easy to understand that the quality of the n-dodecyl mercaptan SAMs is better than that of the t-dodecyl mercaptan.
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Received: 06 January 2009
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| Fund: ;National Natural Science Foundation of China;National Natural Science Foundation of China |
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Corresponding Authors:
LI Degang
E-mail: ldg@sdut.edu.cn
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