Determination of trace amounts of silver in natural waters after flotation using mercury(II) sulphide as a coprecipitant and oleic acid as a surfactant

摘要

A method for the separation and determination of trace amounts of silver in different aqueous media is based on coprecipitation of silver with Hg(II) sulphide,flotation of the precipitate with oleic acid(HOL)surfactant and redissolution with (1:1)concentrated nitric and sulphuric acids.Ag is determined by flame atomic absorption spectrometry(AAS).The different parameters influencing the processes of flotation and determination of silver viz.concentrations of coprecipitant,surfactant and major elements possibly present in some brines,acidity of the medium,agitation time,temperature and the effect of some selected foreign ions are investigated.At the optimal acidity value of the medium(0.2M HNO_3),silver is separated quantitatively(-100%).The procedure is extended to recover and determine silver in natural water samples(3000 mL,successful flotation 3X1000 mL);the mean concentration of Ag being 2.5mug/L.