Multielemental analysis of dried residue from metal-bearing waters by wavelength dispersive X-ray fluorescence spectrometry

Abstract

The purpose of this work was evaluation of instrumental sensitivity and detection limits for determination of elemental composition (20 different elements ranging from Na to Pb) of liquid mining samples by using conventional Wavelength Dispersive X-Ray Fluorescence (WDXRF) instrumentation. Preconcentration of elements from liquid samples was performed by means of a simple dried residue process, and spectral evaluation was carried out by integration of the peak area (using WinQXAS/AXIL package software, International Atomic Energy Agency (IAEA)) instead of the common net peak line intensity traditionally used in conventional WDXRF systems. With the proposed methodology, the calculated detection limits were in the µg L− 1 range (from 0.005 to 0.1 mg L− 1 level depending on the element) in all cases, which is suitable for element determination in most liquid samples involved in environmental studies such as metal mining liquid effluents. The detection limits are also below the established limits of the TCLP 1311 (United States Environmental Protection Agency (US-EPA)) and DIN 38414-S4 (German Standard legislation) procedures, which are commonly used to evaluate the leaching of metals from landfill disposal.

Accuracy of the procedure was confirmed by analysis, based on the German Standard Method DIN 3814-S4, of water lixiviates from three overbank sediment samples collected in two abandoned mining areas. The attained results were compared with those obtained by inductively coupled plasma (ICP) techniques, and acceptable agreement for elements with Z > 20 was found. This study highlights the possibility of using a simple methodology for analysis of liquid mining samples using the WDXRF technique, commonly employed for geochemical exploration of solid samples in environmental studies.