Determination of Toxic Elements in Liquid Hazardous Waste Using Hogh-resolution Energy-dispersive X-ray Fluorescence Spectrometry

Abstract

The analysis of liquid hazardous waste (LHW) prior to disposal using high-temperature incineration or as an alternative fuel is required for process and regulatory control. The typical requirements of the industry sector are rapid screening to support decisions on the most appropriate treatment of the waste. This paper reports the use of high-resolution EDXRF spectrometry for the determination of halides and toxic heavy elements using a rapid technique combined with a unique sample preparation methodology. Calibrations were developed using traceable certified 1000 mg l ^-1 aqueous standards and pure organic solvents. Samples were stabilized in an alumina matrix and measured against a suitable calibration. The benefits of the proposed technique are as follows: (i) ease of obtaining calibration standards; (ii) removal of sample history, i.e. , control of matrix effects; (iii) minimization of analyte loss during sample preparation; (iv) wide range of matrix types measurable using a single calibration, i.e. , clean solvents to turbid sewage sludge; (v) accuracy of measurement, typically within 10% relative in the concentration range 10–100 mg kg ^-1 with a precision of better than 5% relative; and (vi) speed of analysis, for >20 elements typically <15 min from receipt of sample. The results presented show high-resolution EDXRF to be ideally suited to the analysis of LHW owing to good heavy element detection in the atomic number range 30–82 (Zn–Pb). Detection limits are in the range 3–17 mg kg ^-1 for heavy elements and below the working calibration range for Cl, P and S. These limits satisfy typical requirements for process and regulatory control, which are of importance in the range >0.1% m/m for P, S and Cl and >50 mg kg ^-1 for the heavier elements.