Postdoctoral Researcher: Characterising nano-/microplastic particles in plastic recycling processes (# of pos: 2)

Background: Plastic recycling has to increase by almost an order of magnitude in the coming decades to come to a fully circular economy. To facilitate this, plastic losses and/or emissions of nano-/microplastics and contaminants in the recycling process should be minimized. In addition, the emissions of small particles are a concern for water treatment effluent, air quality, and soil. The focus is on quantification and mitigation of losses and emissions in Municipal Solid Waste (MSW) plastic recycling, specifically in the post-sorting steps (grinding, washing, and flake sorting).

Research challenge and objective: To-date there is practically no research available on small plastic particles in plastic recycling processes. Most research on the analysis of small plastic particles in water focusses on environmental samples or wastewater treatment. from (Municipal) Wastewater treatment processes we know that, depending on process type and characteristics, treatment can be both a source and sink of nano-/microplastics. Analysis remains challenging due to several factors, i.e. the large variety of material, small sizes and low concentrations, large contamination risk of samples due to deposition from air and complex sample preparation due to complex chemical matrices with organic material. There is also a lack of proper reference material to validate methods as aged environmental particles are not the same as pristine laboratory particles.

Fortunately, the challenging factors above are less severe for plastic recycling processes. Generally, there is a much better idea about the type of material, type of contaminations, larger concentrations, etc. This helps simplifying the analysis, and choice of analytical tools. The objective is to identify the required analysis methods to quantify emissions and losses. This includes sample preparation techniques.

Facilities: Wetsus has an extensive and state of the art laboratory for water research, including instruments for nano/microplastic research (e.g. FFF-MALS, SEM, Raman, FTIR, Malvern particle analyser, Nanosight, DLS, CLSM, optical laboratory, etc.). For this specific topic, we work in close cooperation with National Test Centre Circular Plastics (location of plastic recycling line) and the Gilbert-Armstrong laboratory (FFF-MALS and fabrication of reference material).