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

The hydrolysis of CH3Hg+ was studied potentiometrically in NaClO4 media in the range 0.1-3.0 mol dm(-3) ionic strength at 25 degrees C. Evaluation of data with the non-linear least-squares computer programs BSTAC and STACO le d us to propose the formation of CH3HgOH and (CH3Hg)(2)OH+ species, The sto ichiometric stability constants obtained for the two species at the differe nt 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 firs t of a series of potentiometric studies on the different equilibria of meth ylmercury with the majority of ions present in natural waters in order to s imulate the behaviour of methylmercury in sea and estuary waters. Copyright (C) 2000 John Whey & Sons, Ltd.