Determination of Heavy Metals and Rare Earth Elements in Bottom Ash of Waste Incineration by ICP-MS With High-Pressure Closed Digestion Method

In this work, nine heavy metals (Cr, Co, Ni, Cu, Zn, Zr, Cd, Ba and Pb) and sixteen rare earth elements in waste incineration were determined by ICP-MS combined with a high-pressure closed digestion method. The samples were completely decomposed by a mixture of acid of HF-HNO3-HCl (1:2:1) at 185 degrees C in high-pressure sealed bombs and a digestion time of 12 h. The operating conditions for ICP-MS (such as temperature of spray chamber, nebulizer gas flow rate, auxiliary gas flow rate, cooler gas flow rate and sampling depth) were also optimized. Here, with Rh as the standard internal element, the obtained linear calibration plots of the studied 25 elements showed relative coefficients (r) were higher than 0. 999 9, and the corresponding detection limits were within 0. 001 similar to 1. 01 ng.g(-1). This proposed method' sdetermination relative standard deviations (RSDs) for waste incineration samples were less than 4. 5% (n=3). Results showed that heavy metals of Cr, Cu, Zn, Zr, Cd, Ba and Pb were relatively high in the studied waste incineration samples, with Pb concentrations as high as (1 459 +/- 8) mg.kg(-1) While the average total REEs was (199 +/- 2) mg.kg(-1) with a decreasing trend and enrichment of light REEs. The successful application of this high-pressure closed digestion ICP-MS method to heavy metals and REEs quantification in waste incineration samples is of valuable guidance in the subsequent waste disposal, and future metal recycling.