Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (05): 419-422.doi: 10.3866/PKU.WHXB20030508

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The Action Mechanism of MMI as Corrosion Inhibitor of Copper for Hydrochloric Acid Pickling

Zhao Yong-Sheng;Pang Zheng-Zhi   

  1. College of Materials Science & Engineering, Beijing University of Chemical Technology, Beijing 100029
  • Received:2002-09-10 Revised:2002-11-17 Published:2003-05-15
  • Contact: Pang Zheng-Zhi

Abstract: The corrosion inhibition property of 2-mercapto-N-methy-imidazole(MMI) for copper in 5%HCl was studied using weight-loss method. The influences of temperature and the concentration of MMI on the corrosion inhibition efficiency were determined, from which the adsorption isotherm was obtained. The heat of adsorption and the effect of the addition of MMI on the activation energy of the corrosion were calculated. The corrosion inhibition mechanism of MMI for copper was proposed. The results indicated that the corrosion inhibition efficiency of MMI for copper increased very sharply with the rise of the concentration of MMI when the concentration was between 3 mmol•L-1 and 8 mmol•L-1 and was approximately constant when the concentration was higher than 8 mmol•L-1, while the addition of MMI accelerated the corrosion of copper if the concentration is lower than 3 mmol•L-1. The interaction force between the adsorbed MMI molecules displayed attractive one on the whole when the concentration was in the range of 4.5 mmol•L-1 to 8 mmol•L-1. The adsorption of MMI on copper surface was a heat-absorbing reaction, and the addition of MMI reduced the activation energy of the corrosion of copper.

Key words: 2-mercapto-N-methy-imidazole(MMI), Corrosion inhibitor, Copper,  Hydrochloric acid, Pickling