TlI and TlIII presence in suspended particulate matter: speciation analysis of thallium in wastewater

Abstract

Environmental context Thallium occurs in the environment in two oxidation states, with TlIII being 1000-fold more toxic than TlI. We present a fractionation and speciation study of thallium in suspended particulate matter from highly polluted wastewater samples, and elucidate the dominant forms of thallium. Abstract Thallium (Tl) is a toxic element, whose toxicity is affected by its redox state. Compared with TlIII, TlI is thermodynamically more stable and less reactive; therefore in aquatic environments, dissolved thallium is mostly present as TlI. However, TlIII could be 1000 times more toxic than TlI. A combination of a fractionation and a speciation study carried out in highly polluted wastewater samples from a mining area in southern Poland in order to characterise chemical speciation of Tl in physically defined fractions is presented here. Total, particulate and dissolved thallium was determined. A leaching experiment based on forming TlIII complexed with diethylene triamine penta-acetic acid – a TlIII–DTPA complex – was performed in filters containing suspended particulate matter after single (0.45µm) and sequential filtration (15 + 0.45µm) of wastewater samples. This is the first speciation study of Tl carried out in suspended particulate matter. The results obtained indicate that the dominant form of Tl in suspended particulate matter is TlI, but TlIII could be found in suspended particulate matter fractions larger than 0.45µm.

Presence of thallium in the environment: sources of contaminations, distribution and monitoring methods

“…Determination of Tl(I) and Tl(III) species was may be carried out in soil samples (Voegelin et al 2015), wastewater samples (Ospina-Alvarez et al 2015), plant tissues (Sadowska et al 2016) and cells (Nowicka et al 2014). Several reports indicate that the use of ICP-MS allows for credible speciation of Tl.…”

Application of Hierarchical Nanostructured WO3 and Fe2O3 Composites for Photodegradation of Surfactants in Water Samples

“…It impairs the stage of nebulization in inductively coupled plasma mass spectrometry (ICP MS) and inductively coupled plasma optical emission spectrometry (ICP OES) measurements (due to surface tension change), while high total organic carbon (TOC) interferes with atomic absorption spectrometers (AAS) detection and ICP ionization (torch clogging). Most of the organic compounds are electroactive, making it virtually impossible to use one of the inexpensive electrochemical methods [6].…”

“…Usually, determination of trace elements in water samples does not require any sample pretreatment before graphite furnace atomic absorption spectrometry (GFAAS) or ICP MS analysis. However, surfactants present in high concentrations, especially in wastewater, need previous decomposition (or at least a significant reduction in their levels) [6,7]. Reproducible results can be obtained after complete decomposition of the organic matter or decomposition to a form that does not interact with the analyte.…”

Identification of complexes involving thallium(I) and thallium(III) with EDTA and DTPA ligands by electrospray ionization mass spectrometry

“…Compared with Tl(III), Tl(I) is more thermodynamically stable and less reactive; therefore, in aquatic environments, dissolved Tl is mostly present as Tl(I). However, Tl(III) could be 1000‐times more toxic than Tl(I) . Determination of Tl in environmental samples can be challenging due to the very low concentrations often present in surface water (usually below 10–100 ng/L) and non‐polluted soil (0.08–1.5 μg/g) …”

“…However, Tl(III) could be 1000-times more toxic than Tl(I). 13 Determination of Tl in environmental samples can be challenging due to the very low concentrations often present in surface water (usually below 10-100 ng/L) and non-polluted soil (0.08-1.5 μg/g). 14 High-performance liquid chromatography (HPLC) with electrochemical detection 15 and inductively coupled plasma mass spectrometry (ICP-MS) [16][17][18][19] are two techniques which are often used for the determination of speciation forms of Tl.…”