Effects of ph, carbonate, orthophosphate, and redox potential on cuprosolvency

Book · Fri Dec 01 00:00:00 EST 1995

OSTI ID:128635

Schock, M R; Lytle, D A ^[1]; Clement, J A ^[2]

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1. Environmental Protection Agency, Cincinnati, OH (United States). Drinking Water Research Division
2. Black and Veatch, Cambridge, MA (United States)

A comprehensive solubility model for copper in drinking water has been developed, that is consistent with available data for copper dissolution and passivation in drinking water systems. Copper solubility (cuprosolvency) is greatly affected by the redox conditions of the systems. The concentration of Cu(I) is dominated by Cu{sub 2}O(s) or CuOH(s) solid phases, plus soluble aqueous ammonia and chloride complexes. In new piping, the concentration of Cu(II) is mainly governed by Cu(OH){sub 2}(s) (cupric hydroxide), rather than CuO(s) (tenorite) or Cu{sub 2}(OH){sub 2}CO{sub 3}(s)(malachite). Complexation of Cu(II) by DIC and hydroxide ion is extremely important. Increases in DIC are predicted to cause significant increases in copper solubility in the pH range of 7.5--10. Utilities may trade off increasing cuprosolvency by DIC addition for ensuring adequate buffering intensity in the finished water. Sufficient dosages of orthophosphate in the pH range of 6.5 to 7.5 may reduce cuprosolvency under oxidizing conditions. Sulfate may decrease cuprosolvency under some conditions, or may interfere with the formation of cupric hydroxide films under mildly alkaline conditions. Dissolved oxygen and chlorine residual play complicated roles in determining copper concentrations after various standing times. Frequently, 48--72 hours are necessary to reach equilibrium levels of copper in disinfected systems.

• OSTI ID: 128635
• Report Number(s): CONF-950304-; TRN: IM9550%%20
• Resource Relation: Conference: Corrosion `95: National Association of Corrosion Engineers (NACE) international annual conference and corrosion show, Orlando, FL (United States), 26-31 Mar 1995; Other Information: PBD: 1995; Related Information: Is Part Of Corrosion/95 conference papers; PB: 5788 p.
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES
COPPER
CORROSION
PIPES
DRINKING WATER
SOLUBILITY
REDOX REACTIONS
COMPLEXES
CARBONATES
HYDROXIDES
CHEMICAL REACTIONS
PH VALUE
OXYGEN
CHLORINE
CHLORAMINES
COMPUTER CALCULATIONS
REDOX POTENTIAL
PHOSPHATES
OXIDATION
EQUILIBRIUM
EXPERIMENTAL DATA