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Release kinetics as a key linkage between the occurrence of flame retardants in microplastics and their risk to the environment and ecosystem: A critical review
- Source :
- Water Research. 185:116253
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- Highlights • Internal diffusion often controls the releases of flame retardants from microplastics. • Fick's law can describe the releases of additive flame retardants from microplastics. • Effects of temperature, plastic matrix, and particle size can be predicted by models. • Weathering of plastic matrix can greatly accelerate the releases of flame retardants. • Low fluxes of flame retardants released from microplastics pose no risk to ecosystem. The widely occurring debris of plastic materials, particularly microplastics, can be an important source of flame retardants, which are one of the main groups of chemicals added in the production of plastics from polymers. This review provides an overview on the use of flame retardants in plastic manufacturing, the kinetics of their releases from microplastics, the factors affecting their releases, and the potential environmental and ecosystem risk of the released flame retardants. The releases of flame retardants from microplastics typically involve three major steps: internal diffusion, mass transfer across the plastic-medium boundary layer, and diffusion in the environmental medium, while the overall mass transfer rate is commonly controlled by diffusion within the plastic matrix. The overall release rates of additive flame retardants from microplastics, which are dependent on the particle's geometry, can often be described by the Fick's Law. The physicochemical properties of flame retardant and plastic matrix, and ambient temperature all affect the release rate, which can be predicted with empirical and semi-empirical models. Weathering of microplastics, which reduces their particle sizes and likely disrupts their polymeric structures, can greatly accelerate the releases of flame retardants. Flame retardants could also be released directly from the microplastics ingested by aquatic organisms and seabirds, with physical and chemical digestion in the bodies significantly enhancing their release rates. Limited by the extremely slow diffusion in plastic matrices, the fluxes of flame retardants released from microplastics are very low, and are unlikely to pose significant risk to the ecosystem in general. More research is needed to characterize the mechanical, chemical, and biological processes that degrade microplastics and accelerate the releases of flame retardants and to model their release kinetics from microplastics, while efforts should also be made to develop environmentally benign flame retardants to ultimately minimize their risk to the environment and ecosystem.
- Subjects :
- Microplastics
Environmental Engineering
0208 environmental biotechnology
Kinetics
Particle (ecology)
02 engineering and technology
010501 environmental sciences
01 natural sciences
Aquatic organisms
fluids and secretions
Ecosystem
Significant risk
Waste Management and Disposal
reproductive and urinary physiology
Internal diffusion
Flame Retardants
0105 earth and related environmental sciences
Water Science and Technology
Civil and Structural Engineering
Ecological Modeling
Pollution
humanities
020801 environmental engineering
Environmental chemistry
Environmental science
Plastics
Water Pollutants, Chemical
Environmental Monitoring
Fire retardant
Subjects
Details
- ISSN :
- 00431354
- Volume :
- 185
- Database :
- OpenAIRE
- Journal :
- Water Research
- Accession number :
- edsair.doi.dedup.....8f48330c9f6b39197a068725c5bcb40f