There are an estimated 5.25 trillion plastic pieces floating in the global oceans (Salvador Cesa, Turra, & Baruque-Ramos, 2017), with approximately 1.5 million tonnes of microplastics polluting the ocean each year, and approximately 35% microplastic pollution is attributed to the fashion industry (Boucher & Friot, 2017). The release of plastic microfibers (MFs) from textiles during laundry represents a significant source of microplastic release into our environment (Browne et al., 2011; Salvador Cesa et al., 2017). Laundering textiles can release 500,000 to over six million MFs for synthetic garments and up to 13 million MFs from cotton garments into the environment per wash. However there are large gaps in our fundamental understanding of the processes by which MFs are released from textiles. This hampers our efforts to mitigate this problem and design methods and processes to reduce MF release into the environment.
This project aims to understand the fundamental mechanisms that cause MFs to become detached and end up in the environment. It will examine the hydrodynamics of MF release in one of our most commonly used textiles — Polyethylene terephthalate (PET). The project will focus on MF detachment events, including the nature of breakage of PET fibers, which is a strong driver of the textiles’ toxicity.
The overall objective of this project is to gain a deeper fundamental understanding of the role of water on MF release from PET during washing and drying procedures. To do this the following work packages will be carried out.
1. Classify PET permeability and different weave structures
2. Design and build a dedicated hydrodynamics test rig (approx. 5cmx5cm cross-section) for visualising the flow through PET at different hydrodynamic pressures and flow speeds.
3. Develop a measurement technique to measure the release of PET fibers in the test rig.
4. Determine how microbial toxicity of the MFs released is affected by the detachment event.
The student will survey the most common textile pollutants and classify these textiles (Objective 1).
The student will perform experiments to identify the main culprits in the release of PET MFs into the environment. They will do this by tracking the fibres from pre-release, to release, to eventual capture. In order to achieve this, they will develop a test rig to measure the flow through and MF release from PET of different compositions (fibre length, diameter and textile weaves, Objective 2). Measuring the MF detachment events involves the resolution of flow phenomena around micron-sized filaments, such as that in (Cummins et al., 2018), and this project will utilise a similar methodology.
The student will verify their findings by comparison to existing studies on the release of MFs. These comparisons will include estimating the volume of MF release in different flow conditions and using measurement techniques developed at NCL (Kelly, Lant, Kurr, & Burgess, 2019) (Objective 3).
The student will prepare the MF samples for microbial toxicity testing and will assess toxicity (Objective 4).
Training & skills
The student will receive significant training in flow diagnostic equipment (Particle Image Velocimetry) and software packages required to analyse the results (e.g., MATLAB or Python). They will also develop skills in statistical analysis (the software package R) and interpretation of data and working with interdisciplinary teams. The student will be supported by the existing PhD students and postdocs based in investigators’ teams at Heriot-Watt and Newcastle Universities. This will create a superb environment to learn new skills and access the experience gained by their peers.
External training: During their project, the student will attend a training course on image analysis, such as a course on ImageJ.
Dissemination of results: The student will learn to present their work at leading scientific conferences such as the annual American Physical Society Division of Fluid Dynamics meeting (USA).
How to apply https://www.iapetus2.ac.uk/how-to-apply/