Grantee Research Project Results
2024 Progress Report: Physicochemical degradation of microplastics
EPA Grant Number: SU840573Title: Physicochemical degradation of microplastics
Investigators: Fakhraei, Habibollah
Institution: Southern Illinois University - Carbondale
EPA Project Officer: Cunniff, Sydney
Phase: I
Project Period: August 1, 2023 through April 23, 2025
Project Period Covered by this Report: August 1, 2023 through July 31,2024
Project Amount: $25,000
RFA: 19th Annual P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet Request for Applications (RFA) (2022) RFA Text | Recipients Lists
Research Category: Urban Air Toxics , Heavy Metal Contamination of Soil/Water , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
Plastics are widely used due to their versatility and numerous applications, but improper disposal often leads to plastic pollution in aquatic environments worldwide. Large plastics degrade over time into microplastics (MPs, size < 5 mm) through physical, biological, and chemical processes, which have been detected in drinking water, seafood, beer, and sea salt. These small particles pose potential risks to human health, aquatic life, and ecosystems. Laundry effluent is identified as a significant source of microfiber pollution, releasing microfibers from synthetic fabrics like nylon and polyester during washing. This project seeks to fill the knowledge gap on microfiber degradation rates and transportation in different environmental media, with a focus on physicochemical degradation factors like ultraviolet (UV) light and hydrolysis. The study aims to understand how microplastics degrade under these conditions and their size distribution upon entering wastewater treatment plants, with potential applications in modifying pretreatment systems to reduce MP discharge, benefiting both the environment and public health.
Progress Summary:
We have made considerable progress in understanding microfiber (MF) release and degradation under various environmental conditions, aligning with the tasks and objectives laid out in the original project proposal. Initially, we selected a diverse range of textile fabrics, including synthetic materials, for testing. This selection allowed us to simulate realistic washing scenarios and understand the differences in microfiber shedding across fabric types. Essential chemical reagents were then acquired to prepare synthetic surface and seawater, creating controlled environments that accurately replicate conditions in natural aquatic systems. To further our understanding of fabric behavior, we conducted pre-laundering and post-laundering characterizations using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). These analyses provided a baseline of fabric composition and structural changes due to laundering, essential for observing degradation patterns and microfiber release in subsequent studies. Laundering trials were performed under varying conditions, such as adjusting water temperature, wash cycle duration, and including detergents and laundry balls. These experiments revealed that different fabric types shed microfibers at varying rates, with synthetic fibers like polyester exhibiting significant microfiber release, while nylon showed relatively lower levels of shedding. Our degradation studies progressed with trials on microfibers exposed to UV light and ongoing hydrolysis experiments. The initial findings suggest that microfiber degradation is influenced by both UV exposure and pH conditions. Microfibers from nylon fabrics showed accelerated breakdown under UV radiation, whereas acrylic fibers demonstrated higher degradation in alkaline conditions. Hydrolysis experiments are currently being conducted at pH levels 9 and 11 to deepen our understanding of how pH impacts degradation, with future UV exposure trials planned to complete this part of the study. In parallel, we explored nanoplastic (NP) interactions with environmental surfaces using Quartz Crystal Microbalance (QCM) analysis. Preliminary results indicate that polyethylene nanoplastics demonstrate minimal deposition on bare silica surfaces, regardless of ionic strength. However, when the surfaces are coated with natural organic matter (NOM), NP adhesion significantly increases, especially when calcium chloride (CaCl2) is present in the solution as ionic strength. This observation underscores the critical role of NOM in enhancing NP deposition, suggesting implications for improving filtration systems or developing containment strategies to mitigate nanoplastic pollution in aquatic environments. Overall, the progress to date aligns with the project's primary objectives, contributing valuable insights into microfiber release dynamics, degradation mechanisms, and nanoplastic behavior. These findings are particularly relevant for informing environmental policies and designing effective pollution control measures.
Future Activities:
The next steps in this research will focus on completing the remaining tasks to achieve the project's milestones. We plan to expose the remaining microplastics generated to UV irradiation and continue hydrolysis studies to further explore degradation under combined environmental conditions. Once this task is complete, we will conduct additional FTIR and SEM analyses on the degraded microplastics, providing detailed insights into structural and compositional changes. These analyses will help us understand the transformations that occur during environmental exposure and their implications for microfiber persistence in aquatic systems. Following these degradation and characterization studies, we will proceed with the QCM investigations. Here, we will measure the mass deposition of plastic on NOM-coated and uncoated QCM crystals, enabling us to quantify degradation and deposition behaviors under various ionic strengths. This part of the project will expand our understanding of nanoplastic adhesion and release in natural water systems, potentially guiding improved filtration technologies. As the project reaches its final stages, we will focus on dissemination activities to share our findings with the broader scientific community.
Journal Articles:
No journal articles submitted with this report: View all 3 publications for this projectSupplemental Keywords:
UVA irradiation, nanoscale interactions, water treatmentProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.