Analusis 27, 472-475 (1999)
DOI: 10.1051/analusis:1999128

Determination of mercury traces in products of TiO₂ manufacturing

N. Mikac¹, S. Gressier² and M. Wartel<sup>2

1</sup>  Centre for Marine and Environmental Research, Rudjer Boslkovic' Institute, P.O. Box 1016, 10001 Zagreb, Croatia
²  Laboratoire de Chimie Analytique et Marine, UPRESA CNRS 8013 Université des Sciences et Technologies de Lille, Bât. C8, 59 655 Villeneuve D'Ascq Cedex, France

Abstract
A simple method for the determination of mercury traces in co-products and final products of titanium (IV) oxide manufacturing was developed. It was shown that different procedures recommended for the total digestion of such materials (using mixtures of HF, HNO₃, HCl and HClO₄) could be efficiently replaced by an unique partial digestion method based on mercury leaching from sample by HNO₃. Partial digestion method was much quicker and more sensitive than total digestion methods. Mercury was detected with cold vapour atomic fluorescence spectroscopy and a detection limit of 10 pgHg/g was achieved. The method was validated using certified reference materials PACS-1 (NRCC) and maroccan phosphate rock (BCR). Regarding mercury content in analysed samples from the point of view of the ecological risk, only residual material after first digestion of raw material with H₂SO₄ were found to contain mercury concentrations higher than accepted background value for sediment and soils (0.1 μgHg/g). All other co-products as well as the final product titanium (IV) oxide were almost free of mercury (< 0.01 - 30 ngHg/g).

Key words: Mercury traces / partial digestion by nitric acid / titanium dioxide.


© EDP Sciences, Wiley-VCH 1999