Role of Solution Chemistry on Corrosion of Copper in Tap Water: Effect of Sulfate Ion Concentration on Uniform and Localized Attack

Reda, M. R.; Alhajji, J. N.

doi:10.5006/1.3292118

Cited by 14 publications

(16 citation statements)

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“…The effect of each anion on the stability of the passive film on copper has been widely studied in different environments. 38,41,55 Furthermore, combinations of aggressive anions and inhibiting anions ͓͑SO 4 2− ͔/͓HCO 3 − ͔, 7,9,55,56 ͓Cl − ͔/͓HCO 3 − ͔, 42 and ͓SO 4 2− ͔/͓OH − ͔ 57 ͒ have also been a subject of some studies, and some critical anion ratios have been specified to minimize the pitting problems. 9,36 The mechanism is due to either the buffering capability which prevents local acidity or the formation of a possibly protective basic copper carbonate film, CuCO 3 ͑cupric carbonate͒, Cu͑OH͒ 2 ·CuCO 3 ͑mala-chite͒, Cu͑OH͒ 2 ·2CuCO 3 ͑azurite͒, or any combination of these minerals.…”

mentioning

confidence: 99%

Passivity and Pit Stability Behavior of Copper as a Function of Selected Water Chemistry Variables

Cong

Michels

Scully

2009

J. Electrochem. Soc.

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The electrochemical pitting behavior of UNS C11000 copper was investigated in a synthetic potable water found to cause pitting. Tests were also conducted in several other HCO 3 − , SO 4 2− , and Cl − containing waters with systematic variations in concentrations of these species. Studies of the effect of water chemistry on passivity, uniform corrosion, and pitting were accomplished using the cyclic voltammetry method complemented by various diagnostic methods. Certain water chemistry concentrations promote pitting. Critical pitting potentials ͑E Pit ͒ for copper pitting are decreased by certain water chemistry variables. High ͓SO 4 2− ͔/͓OH − ͔, ͓SO 4 2− ͔/͓HCO 3 − ͔, and Cl − /͓HCO 3 − ͔ ratios lower pitting potentials while an increase in alkalinity ͑increasing ͓OH − ͔ or ͓HCO 3 − ͔/͓CO 3 2− ͔͒ improves passivity and raises pitting potentials. HCO 3 − /CO 3 2− can protect copper surfaces by forming carbonate containing minerals. However, carbonated species are less beneficial toward passivity compared to OH − with respect to passivation efficiency. Empirical equations that forecast pitting and repassivation potentials as a function of selected water chemistry variables were developed by linear regression analysis based on experimental pitting and repassivation potential trends with HCO 3 − , Cl − , and SO 4 2− content. The origins of the trends with water chemistry variables are discussed.

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confidence: 99%

Passivity and Pit Stability Behavior of Copper as a Function of Selected Water Chemistry Variables

Cong

Michels

Scully

2009

J. Electrochem. Soc.

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“…Studies have shown that copper corrosion is greatly influenced by environmental factors—pH, temperature, and bicarbonate concentration—as well as concentrations of dissolved oxygen, chloride, nitrate, sulfate, and chlorine residual (Reda & Alhajji, 1996; Edwards et al, 1994; Fujii, 1988).…”

Section: Resultsmentioning

confidence: 99%

Effect of chlorine on corrosion in Drinking Water Systems

Cantor¹,

Park²,

Vaiyavatjamai³

2003

Journal AWWA

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The federal Ground Water Rule may require some water utilities that do not use disinfection to begin doing so. A common method of disinfection is to add chlorine to the water. A study was performed to investigate the corrosive effects of chlorine in drinking water systems out of concern for staying in compliance with the corrosion control stipulations of the Lead and Copper Rule. Comparative corrosivity experiments using pipe loops were performed at two test sites. In this study, iron appears to be the most affected by free chlorine addition, followed by copper, followed by lead, which may or may not experience increased corrosion.Elevating the pH of the water at one site (originally at a pH of 7.8, 140 mg/L as calcium carbonate [CaCO 3 ] total alkalinity, 6 mg/L dissolved oxygen) was beneficial in counteracting the corrosive effect of chlorinated water on iron. However, in this case, the elevation of pH was not beneficial in controlling corrosion of lead or copper. Adding orthophosphate decreased corrosion of lead and iron in contact with chlorinated water at the other site (original pH of 7.4, 290 mg/L as CaCO 3 total alkalinity, 11 mg/L dissolved oxygen). However, copper corrosion appeared to reach an increased level in the long term.

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“…Researchers have found that newly installed pipe may require several months to attain stable, minimum metal values and that stability may never be achieved because of fluctuating water chemistry 16 . Studies have shown that copper corrosion is greatly influenced by pH, temperature, and bicarbonate concentration, as well as concentrations of dissolved oxygen, chloride, nitrate, sulfate, and chlorine residual 17 – 19 . In other studies, 9 , 20 orthophosphate has been found to reduce copper concentration in the treated water to below that of the untreated water.…”

Section: Resultsmentioning

confidence: 99%

Use of polyphosphate in corrosion control

Cantor¹,

Denig-Chakroff²,

Vela³

et al. 2000

Journal AWWA

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Case studies from three Wisconsin utilities found that polyphosphate blends used for corrosion control led to increased metal concentrations in the water. When polyphosphate blends are added to water systems under certain conditions, leaching of pipe metal into the water may be significantly increased rather than decreased. Case studies of three Wisconsin water utilities uncovered possible negative consequences of using polyphosphate for corrosion control. These experiences suggest that water providers must exercise caution when adding polyphosphate to drinking water systems. Utilities should conduct off‐line tests before using polyphosphate, and full‐scale systems should be frequently monitored after polyphosphate addition. More research is needed to define the proper use of polyphosphates and to investigate alternatives to polyphosphates.

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Role of Solution Chemistry on Corrosion of Copper in Tap Water: Effect of Sulfate Ion Concentration on Uniform and Localized Attack

Cited by 14 publications

References 1 publication

Passivity and Pit Stability Behavior of Copper as a Function of Selected Water Chemistry Variables

Passivity and Pit Stability Behavior of Copper as a Function of Selected Water Chemistry Variables

Effect of chlorine on corrosion in Drinking Water Systems

Use of polyphosphate in corrosion control

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