Potentiometric study of the hydrolysis of (CH3)Hg+ in NaClO4: construction of a thermodynamic model

Abstract

The hydrolysis of CH3Hg+ was studied potentiometrically in NaClO4 media in the range 0.1–3.0 mol dm−3 ionic strength at 25 °C. Evaluation of data with the non-linear least-squares computer programs BSTAC and STACO led us to propose the formation of CH3HgOH and (CH3Hg)2OH+ species. The stoichiometric ­stability constants obtained for the two species at the different ionic strengths were correlated by means of Modified Bromley Methodology (MBM) to obtain the corresponding thermodynamic equilibrium constants, as well as the interaction parameters of the soluble species. This is the first of a series of potentiometric studies on the different equilibria of methylmercury with the majority of ions present in natural waters in order to simulate the behaviour of methylmercury in sea and estuary waters. Copyright © 2000 John Wiley & Sons, Ltd.