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Microelectrode Investigation on the Corrosion Initiation at Lead−Brass Galvanic Interfaces in Chlorinated Drinking Water
Citation:
Ma, X., D. Lytle, AND W. Lee. Microelectrode Investigation on the Corrosion Initiation at Lead−Brass Galvanic Interfaces in Chlorinated Drinking Water. LANGMUIR. American Chemical Society, Washington, DC, 35(40):12947-12954, (2019). https://doi.org/10.1021/acs.langmuir.9b02168
Impact/Purpose:
Excessive corrosion of drinking water distribution system (DWDS) materials can cause pipe damage, water leaks, and degrade water quality, which can create structural integrity issues, economic losses, and public health issues. Galvanic corrosion occurs when two dissimilar metals are in electrical contact with each other in an electrolyte and one corrodes preferentially before the other. Galvanic corrosion can be an important source of lead in drinking, however, the understanding of the process could be improved. The purpose of this study was to use multiple microelectrodes to evaluate the effect of water flow, pH, and dissolved inorganic carbon concentration, on the pH, free chlorine, and dissolved oxygen concentration changes across the surface of brass: lead-solder coupons. This work fits under the Safe and Sustainable Water Resources Program’s distribution system corrosion analysis and modeling research efforts (SSWR 6.01C) and is external EPA collaboration with University of Central Florida research team.
Description:
In this study, microelectrodes were applied to construct two-dimensional (2D) map of pH and free chlorine for better understanding local water chemistry adjacent to brass-lead galvanic joints surface. The impact of water flow, dissolved inorganic carbon, and pH were investigated. A maximum pH difference of 7.5 between brass and lead-tin solder joint surface was found at pH 7, 2 mg Cl2·L-1, and 10 mg C·L-1 under stagnation where the lowest pH (2.8) was observed at the leaded-solder surface, indicating the anodic site and potential for elevated soluble lead to build up. High DIC water under flowing conditions showed no galvanic reaction probably due to the sufficient buffering capacity. Free chlorine consumption near the metal surface was greater under stagnation regardless of bulk pH. However, oxygen consumption was minimal where free chlorine residuals were present.
URLs/Downloads:
DOI: Microelectrode Investigation on the Corrosion Initiation at Lead−Brass Galvanic Interfaces in Chlorinated Drinking Water
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