Chemical speciation of environmentally significant metals with inorganic ligands Part 2: The Cu 2+ -OH - , Cl - , CO 3 2- , SO 4 2- , and PO 4 3- systems (IUPAC Technical Report)

• Published in: Pure and applied chemistry 2007, Vol.79 (5), p.895
• Main Authors: Powell, Kipton J., Brown, Paul L., Byrne, Robert H., Gajda, Tamas, Hefter, Glenn, Sjöberg, Staffan, Wanner, Hans
• Format: Article
• Language: English
• Subjects: chemical speciation; copper; environmental; IUPAC Analytical Chemistry Division; ligands; stability constants
• ISSN: 0033-4545; 1365-3075
• DOI: 10.1351/pac200779050895

Complex formation between Cu II and the common environmental ligands Cl - , OH - , CO 3 2- , SO 4 2- , and PO 4 3- can have a significant effect on Cu II speciation in natural waters with low concentrations of organic matter. Copper(II) complexes are labile, so the Cu II distribution amongst these inorganic ligands can be estimated by numerical modeling if reliable values for the relevant stability (formation) constants are available. This paper provides a critical review of such constants and related thermodynamic data. It recommends values of log 10 β p,q,r ° valid at I m = 0 mol kg -1 and 25 °C (298.15 K), along with the equations and specific ion interaction coefficients required to calculate log 10 β p,q,r values at higher ionic strengths. Some values for reaction enthalpies, ΔrHm, are also reported where available. In weakly acidic fresh water systems, in the absence of organic ligands, Cu II speciation is dominated by the species Cu 2+ (aq), with CuSO 4 (aq) as a minor species. In seawater, it is dominated by CuCO 3 (aq), with Cu(OH) + , Cu 2+ (aq), CuCl + , Cu(CO 3 )OH - , Cu(OH) 2 (aq), and Cu(CO 3 ) 2 2- as minor species. In weakly acidic saline systems, it is dominated by Cu 2+ (aq) and CuCl + , with CuSO 4 (aq) and CuCl 2 (aq) as minor species.