Fast and simple method for simultaneous determination of palladium and rhodium in spent automotive catalysts by high-resolution continuum source electrothermal atomic absorption spectroscopy

Abstract

This work established a novel and fast method for the simultaneous determination of palladium and rhodium in spent automotive catalysts by high-resolution continuum source electrothermal atomic absorption spectroscopy (HR-CS ETAAS). For this purpose, a simple approach for the extraction of Pd and Rh from auto catalysts with aqua regia (HCl + HNO3 (3:1)) leaching was developed. The optimum conditions for leaching of both elements in an open system are 4 h, at 108 °C and a solid-to-liquid ratio of 1:40. Palladium and rhodium concentrations in obtained leachate were determined simultaneously in one firing using the less sensitive adjacent secondary lines for Pd at 360.955 nm (7.7% relative sensitivity) and for Rh at 361.251 nm (2.2% relative sensitivity). The pyrolysis and atomization temperatures were 1200 °C and 2600 °C, respectively. Under these conditions, the limits of detection for Pd (0.19 mg kg−1) and Rh (0.48 mg kg−1) were relatively high but the sensitivity of the developed method corresponds to common concentrations of the elements in spent automotive catalysts. The repeatability of the method expressed as a relative standard deviation was typically 10% for Pd and 7% for Rh.The trueness of the method was confirmed by analysis of the certified reference material – spent automobile catalyst (ERM EB 504). The recoveries of Pd and Rh from the spent automobile catalyst were 96.9%, and 87.9%, respectively. The method was successfully applied to the simultaneous determination of Pd and Rh in spent automotive catalysts without preliminary chemical separation.