Corrosion and Leaching of Copper Tubing Exposed to Chlorinated Drinking Water
The leaching of lead and copper from plumbing materials is a source of metals in drinking water and is a public health concern. This work investigated the influence of free chlorine (HOCl/OCl-) on the level of copper in water in contact with the solid metal, and proposed an oxidation-dissolution mechanism to explain copper leaching. Experimental results are presented for the leaching of copper metal exposed to chlorine-disinfected water under various pH, free chlorine, dissolved oxygen, total carbonate, chloride, and water volume conditions. The rate of copper leaching is found to be accelerated in waters with high free chlorine concentrations and low pHs. The leaching is explained by a proposed mechanism involving two consecutive steps: (1) direct oxidative attack on the solid metal surface by the free chlorine, followed by (2) dissolution of the partially oxidized copper surface as determined by the solubility of the copper mineral products at a particular pH.
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