Analysis of Recycled Materials by EDXRF

Importance of the Topic

Rising environmental awareness and legislation are driving the use of recycled materials across industries such as automotive, electronics and packaging. Ensuring the safety, quality and performance of recycled plastics, rubbers, glasses and novel feedstocks demands rapid, accurate elemental analysis. Energy dispersive X-ray fluorescence (EDXRF) offers non-destructive screening and quantitative capabilities without complex sample preparation.

Objectives and Study Overview

This application note demonstrates how the Shimadzu EDX-7200 EDXRF spectrometer can be applied to:

• Screen for toxic elements (RoHS, Cl, Sb, P, Sn) in recycled polyethylene.
• Quantify major and minor constituents in recycled rubber and packaging paper.
• Monitor chlorine levels in refuse paper and plastics fuel (RPF) for boiler corrosion control.
• Distinguish soda-lime from lead glass and verify RoHS compliance in recycled glass toys.

Methodology

Samples in solid, powder and pellet form were analyzed using two workflows:

• Screening analysis for target elements (Cd, Pb, Cr, Hg, Br, Cl, Sb, P, Sn) at multiple tube voltages (10–50 kV) and filters, with automatic current and fixed counting times.
• Qualitative and quantitative multi-element analysis (Na–U) under vacuum, using optimized voltages (15 kV for light elements, 50 kV for heavier) and filter selections.

Used Instrumentation

• Shimadzu EDX-7200 Energy Dispersive X-ray Fluorescence Spectrometer
• Silicon Drift Detector (SDD)
• Rh target X-ray tube, variable voltages (10–50 kV) and primary filter options
• Atmospheres: air for screening, vacuum for full spectrum analysis

Main Results and Discussion

• Recycled Polyethylene: Screening of nine elements showed all analytes below regulatory thresholds (e.g. Cl ~152 ppm, Br ~20 ppm; Cd and Hg not detected).
• Recycled Rubber: Composition analysis revealed ~85 % styrene-butadiene rubber, with Ca (~9.96 %), S (~2.21 %), Zn (~1.20 %) and trace metals supporting formula verification.
• RPF Chlorine Monitoring: Cl levels measured at multiple sampling points ranged from 0.050 % to 0.091 %, enabling classification according to JIS Z 7311 to avoid boiler corrosion.
• Recycled Glass Toys: RoHS elements in color-sorted glass toys were below limits (Pb ~64 ppm, Cr ~11 ppm), and spectral overlays distinguished soda-lime vs lead glass for sorting.
• Eggshell-Based Packaging Paper: Major CaCO3 content (40.8 %) and polyethylene binder (58.8 %), with minor Si, Mg, S, Zn and trace metals quantified to assess material quality.

Benefits and Practical Applications

EDXRF enables rapid quality control and regulatory screening of reclaimed feedstocks without chemical digestion. It supports:

• Compliance checks for hazardous substances in recycled plastics and glass.
• Process control in rubber compounding and fuel production.
• Sorting of mixed-color or mixed-composition glass streams.
• Development of novel recycled materials (e.g. biomineral-based papers).

Future Trends and Possibilities for Use

Advancements in detector sensitivity, software automation and smaller X-ray sources will expand EDXRF applications to on-line monitoring and fine-scale mapping. Integration with robotics and machine learning could further accelerate sorting, screening and process feedback in circular-economy operations. EDXRF may also support emerging recycled composites and bio-based materials as they enter commercial production.

Conclusion

The Shimadzu EDX-7200 offers versatile, non-destructive elemental analysis for a wide range of recycled materials. Its screening and quantitative modes deliver essential data for regulatory compliance, quality assurance and process optimization, reinforcing its role in sustainable material reuse.

References

JIS Z 7311 Classification of Refuse Paper and Plastics Fuel
JIS Z 7302-6 Chemical Analysis of Chlorine in RPF