Prussian Blue Loaded on Magnetic Sepiolite Nanocomposites for Detection of Thallium Using Total Reflection X‑ray Fluorescence Spectroscopy

As a highly toxic element, it is crucial to accurately detect the concentration of ththalium (Tl) on-site in the environment. However, the low concentration is out of the measurement range of many instruments. Pre-enrichment will significantly decrease the lower detection limit of the instruments. Here, Prussian blue loaded on magnetic sepiolite (PB/Fe3O4/SEP) nanocomposites have been synthesized and utilized as an adsorbent to enrich and separate the trace amounts of heavy metal Tl­(I) from wastewater. The maximum adsorption capacity of PB/Fe3O4/SEP nanocomposites for Tl­(I) is about 177.3 mg·g–1, and the recovery efficiency is over 94%. After pre-enrichment, the detection limit of total reflection X-ray fluorescence spectroscopy (TXRF) was reduced to 0.84 μg·L–1, about 100 times greater than that without enrichment. In all, the combined strategy of pre-enrichment by PB/Fe3O4/SEP nanocomposites and detection by TXRF is suitable for on-site emergency monitoring of Tl­(I).