Complexation of CH3Hg+ with chloride, sulfate and carbonate in NaClO4: construction of thermodynamic models

✍ Scribed by J. Sanz; J. C. Raposo; A. de Diego; J. M. Madariaga

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 171 KB
• Volume: 16
• Category: Article
• ISSN: 0268-2605
• DOI: 10.1002/aoc.307

✦ Synopsis

The complexation of CH 3 Hg with major ions present in sea and estuary waters (Cl À , SO 4 2À and CO 3 2À ) was studied potentiometrically in an NaClO 4 medium in the ionic strength range 0.1± 3.0 mol dm À3 at 25 °C. The potentiometric data, treated with non-linear least squares computer programs, led us to establish the formation of the species CH 3 HgCl in equilibrium with chloride, CH 3 Hg(SO 4 ) À species with sulfate and no complex with carbonate. The stoichiometric stability constants obtained at the different ionic strengths were correlated by means of the modified Bromley methodology (MBM) to determine the corresponding thermodynamic constants and interaction parameters. This study is the second of a series designed to simulate, using the MBM thermodynamic model, the behaviour of methylmercury in different conditions of sea and estuary waters. In the first study of the series, the hydrolysis equilibria of methylmercury in NaClO 4 ionic media were established.