Determination of Thallium Traces from Aqueous Solutions Using Iron(III) Hexamethylenedithiocarbamate as a Flotation Collector and Subsequent Electrothermal Atomic Absorption Spectrometry

Abstract

Hexamethyleneammonium hexamethylenedithiocarbamate (HMA-HMDTC) was used as a new flotation reagent for enrichment and separation of thallium traces from aqueous Solutions. HMA-HMDTC added to the first precipitate collector of hydrated iron(III) oxide (Fe2O3 ⋅ xH2O) gives the second precipitate collector of iron(III) hexamethylenedithiocarbamate (Fe(HMDTC)3). During the coprecipitation step, thallium ions are incorporated in the structure of the collector particles forming a sublate, which is separated from the processed water phase by flotation. After the preconcentration and separation step, a quantitative analysis is performed by electrothermal atomic absorption spectrometry (ETAAS). The diverse experimental parameters affecting the flotation efficiency were determined and optimized. It was ascertained by a proposed procedure that total thallium can be separated quantitatively by addition of 10 mg FeIII and 3 mL 0.1 mol/L HMDTC- to the sample at pH = 6.0. The applicability of the proposed new procedure has been verified by the analysis of natural water samples by the method of standard additions and by inductively coupled plasma - atomic emission spectrometry (ICP-AES), as an independent comparative method. The limit of detection for thallium in this method is 0.024 μg/L