Voltammetric Evidence Suggesting Ag Speciation Is Dominated by Sulfide Complexation in River Water

摘要

Using voltammetric methods, free HS~-/H_2S, acid volatile sulfide (AVS), and only Cr(II) reducible sulfide (OCRS) fractions were measured in seven rivers spanning the mid-Atlantic region of the united States to determine the effect of sulfide complexation on dissolved Ag (Ag_(diss)) speciation in freshwaters. In all waters, the AVS: Ag_(diss) ratio was observed to be greater than 600. This increased to a range of 1000-5000 for rivers that received sewage treatment plant (STP) effluent. In laboratory experiments, Ag was observed to quickly (<1 min.) replace both Cu and Zn in metal sulfide solutions, indicating that the measured AVS concentrations in natural waters provide an excess pool of available sulfide for complete Ag complexation.