Determination of mercury traces in products of TiO2 manufacturing

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).