Effect of ions on carbon steel corrosion in cooling systems with reclaimed wastewater as the alternative makeup water

Abstract

The corrosion behavior of carbon steel in cooling systems using reclaimed wastewater as the makeup water was investigated. Effect of typical ions (Cl⁻, , , and ) on the corrosion of carbon steel in cooling systems was evaluated. The electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy were used to measure the corrosion rate and analyze the corrosion processes. Also scanning electron microscopy, Fourier transform infrared spectrometer and energy dispersive spectroscopy were applied to surface analysis. Among the examined ions, Cl⁻ had the highest influence on the corrosion of the carbon steel, followed by , , and . During cooling cycle, the corrosion process of carbon steel was controlled by cathodic reaction. Corrosion rate increased at the initial stage and then decreased thereafter due to the combined effect of ions and corrosion layer. The ions accelerated the initial corrosion of carbon steel in cooling system, while the corrosion layer hindered this effect. The corrosion layer was dense, uniform, and made up of crystalline particles and the main corrosion products were ferric hydroxides and iron oxide.

Keywords:

• Carbon steel
• Reclaimed wastewater
• Corrosion
• Electrochemical methods
• Ion influence

Acknowledgments

This research was supported by the Jiangsu Science and Technology Support Plan (BE2009604) and the National Science and Technology Major Project: Control and Management of the Polluted Water Bodies (2012ZX07301-001).