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Aggregation kinetics of UV irradiated nanoplastics in aquatic environments
- Source :
- Water research. 163
- Publication Year :
- 2019
-
Abstract
- Nanoplastics (NPs) derived from degradation of macroplastics and microplastics possess potential threat to aquatic biota and human health. Their fate and transport in aquatic systems are mainly governed by aging processes and aggregation behavior. In this study, we simulated plastic aging process using UV-irradiation and compared the aggregation kinetics of fresh versus aged polystyrene NPs (PSNPs) under aqueous conditions. The results showed that fresh PSNPs had strong negative surface charge and exhibited both reaction- and diffusion-limited aggregation regimes, in agreement with classic Derjaguin−Landau−Verwey−Overbeek (DLVO) theory. Divalent electrolytes were 10–15 times more effective in inducing PSNP aggregation than monovalent electrolytes. The aging process inhibited PSNP aggregation in NaCl solutions by increasing the negative charge on PSNP surface and the organic matter content in solution, while promoted PSNP aggregation in CaCl2 solutions due to interactions between Ca2+ and carboxyl groups formed on aged PSNP surface. Such distinct behaviors were consistent with characterizations by contact angle measurements, potentiometric titration, total organic carbon (TOC) analysis, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Hamaker constants obtained from DLVO fitting decreased from 3.5 × 10−21 J for fresh PSNPs to 1.5 × 10−21 J for aged PSNPs. This study indicated that UV-irradiation plays a vital role in governing the fate, transport, and potential hazards of PSNPs in aquatic environments.
- Subjects :
- Environmental Engineering
Ultraviolet Rays
Hamaker constant
0208 environmental biotechnology
Potentiometric titration
02 engineering and technology
010501 environmental sciences
01 natural sciences
Contact angle
chemistry.chemical_compound
Electrolytes
Surface charge
Fourier transform infrared spectroscopy
Waste Management and Disposal
0105 earth and related environmental sciences
Water Science and Technology
Civil and Structural Engineering
Aqueous solution
Chemistry
Ecological Modeling
Pollution
020801 environmental engineering
Kinetics
Chemical engineering
DLVO theory
Polystyrenes
Polystyrene
Plastics
Subjects
Details
- ISSN :
- 18792448
- Volume :
- 163
- Database :
- OpenAIRE
- Journal :
- Water research
- Accession number :
- edsair.doi.dedup.....47bac3c03d520d5db2b4dbe56e73a05e