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Studying the concentration of polymers in blended microplastics using 2D and 3D Raman mapping
Mehrdad Lotfi Choobbari1, Jennifer Ferguson2, Niko Van den Brande3
1Department of Applied Physics and Photonics, Brussels Photonics, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
Scientific Reports
|May 12, 2023
Summary
This study introduces 3-D Raman mapping to analyze blended microplastics (MPs), revealing polymer distribution and concentration. A line-focus method significantly reduces analysis time for these complex plastic pollutants.
Area of Science:
- Environmental Science
- Materials Science
- Analytical Chemistry
Background:
- Microplastic (MP) analysis has largely focused on single-polymer particles, neglecting the prevalence of blended plastics in the environment.
- Polyolefins (POs), such as Polypropylene (PP) and Low-density Polyethylene (LDPE), are widely used and abundant environmental pollutants, often found in blended forms.
Purpose of the Study:
- To develop and apply 3-D Raman mapping for characterizing the internal morphology and polymer distribution within blended microplastics (B-MPs).
- To quantitatively assess polymer concentrations in B-MPs and evaluate the precision of the analysis using a Concentration Estimate Error (CEE) parameter.
- To investigate the influence of different excitation wavelengths and introduce a line-focus laser profile to enhance measurement efficiency.
Main Methods:
- Utilized 3-D Raman mapping to visualize the internal structure and polymer distribution of PP/LDPE blended microplastics.
- Performed quantitative analysis to determine polymer concentrations and calculated the Concentration Estimate Error (CEE).
- Investigated the effect of four excitation wavelengths (405, 532, 633, and 785 nm) and implemented a line-focus laser beam profile.
Main Results:
- 2-D Raman mapping was insufficient for surface analysis, highlighting the necessity of 3-D analysis for B-MPs.
- 3-D Raman mapping successfully visualized polymer distribution and enabled quantitative concentration estimation within B-MPs.
- The application of a line-focus laser beam profile reduced measurement time from 56 to 2 hours, significantly improving efficiency.
Conclusions:
- 3-D Raman mapping is essential for comprehensive analysis of blended microplastics, providing insights into internal polymer morphology and concentration.
- The developed methodology offers precise quantitative analysis of polymer composition in complex B-MPs.
- The optimized measurement protocol using a line-focus laser significantly accelerates the analysis of microplastic samples.
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