Chemical speciation of environmentally significant metals with inorganic ligands. Part 4: The Cd2+ + OH-, Cl-, co32-, So42-, and Po43- systems (IUPAC technical report)

Abstract

The numerical modeling of CdII speciation amongst the environmental inorganic ligands Cl-, OH-, CO32-, SO42-, and PO43- requires reliable values for the relevant stability (formation) constants. This paper compiles and provides a critical review of these constants and related thermodynamic data. It recommends values of log10 βp,q,r° valid at Im = 0 mol kg-1 and 25 °C (298.15 K), along with the equations and empirical reaction ion interaction coefficients, Δε, required to calculate log10 βp,q,r values at higher ionic strengths using the Brønsted-Guggenheim-Scatchard specific ion interaction theory (SIT). Values for the corresponding reaction enthalpies, ΔrH, are reported where available. Unfortunately, with the exception of the CdII-chlorido system and (at low ionic strengths) the CdII-sulfato system, the equilibrium reactions for the title systems are relatively poorly characterized. © 2011 IUPAC.