Analysis of liquid hazardous waste fuels (LHWF) per ASTM D5839 with ARL QUANT’X EDXRF Spectrometer

Importance of the Topic

Accurate determination of toxic trace elements in liquid hazardous waste fuels is essential to ensure safe disposal, meet regulatory requirements, and optimize energy recovery in industrial combustion processes.

Objectives and Study Overview

This analysis applies ASTM D5839 to quantify silver, cadmium, chromium, nickel, lead and antimony in liquid hazardous waste fuels using the Thermo Scientific ARL QUANTX energy dispersive x-ray fluorescence spectrometer equipped with a silicon drift detector. The study establishes calibration routines, evaluates precision and accuracy, and determines detection limits over a concentration range of 0 to 500 ppm.

Methodology and Instrumentation

Sample preparation follows ASTM D5839 by blending equal masses of the waste fuel and graphite powder to homogenize multiphase mixtures and minimize matrix effects. The mixture is milled, then 4 grams of paste is placed in an open sample cup sealed with a 4 µm polypropylene film. Calibration employs 24 standards combining six elements at five concentration levels plus blanks and validation samples. An empirical matrix correction using alpha coefficients is applied via the instrument software. Spectra are acquired under ambient air at three excitation settings: low voltage with a thin palladium filter for chromium and nickel; medium voltage with a thick palladium filter for lead; high voltage with a thick copper filter for silver, cadmium and antimony. Each condition is measured for four minutes.

Main Results and Discussion

Calibration curves for all elements exhibit correlation coefficients greater than 0.9996 and standard errors of estimate below 5 ppm. Repeatability tests at 250 ppm show relative standard deviations below 1%. Minimum detection limits under 240 seconds range from 0.4 to 2.2 ppm and remain below 4.4 ppm with only one minute per condition. The high resolution of the silicon drift detector effectively resolves spectral overlaps, ensuring reliable quantification.

Practical Benefits and Applications

This EDXRF method allows rapid, cost-effective screening of toxic metals in liquid waste fuels without the need for inert gases. It supports regulatory compliance, reduces analytical turnaround, and enables energy recovery from hazardous wastes in industrial furnaces.

Instrumentation Used

• Thermo Scientific ARL QUANTX EDXRF spectrometer with silicon drift detector
• Ball mixer mill for sample homogenization
• Graphite powder and paraffinic oil standards
• Sample cups and 4 µm polypropylene film seals

Future Trends and Potential Applications

Improvements in detector sensitivity and advanced spectral deconvolution algorithms are expected to shorten analysis times and lower detection limits further. Automation of sample handling and integration with process control systems could enable on-line monitoring of waste streams. Extending the element range and adapting protocols for solid residues will broaden the technique s applicability in waste management.

Conclusion

The ASTM D5839 EDXRF procedure implemented on the ARL QUANTX spectrometer delivers accurate, precise and efficient quantification of six hazardous elements in liquid waste fuels. Its simplicity, speed and low operating costs make it a valuable tool for environmental monitoring and energy recovery initiatives.