Thesis
FATE AND TRANSPORT OF SECONDARY NANOSCALE PLASTICS IN THE AQUATIC ENVIRONMENT
Washington State University
Master of Science (MS), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004389
Handle:
https://hdl.handle.net/2376/124591
Abstract
Plastics products are becoming more popular because of their cheap production cost, highflexibility, and convenience to use. These products end up in the environment as wastes when
they are not recycled or managed properly. As a result, natural energy sources, such as sunlight,
can degrade them and generate secondary micro and nanoscale plastics. While there are research
findings of the fate and transport of nanoplastics using model nanospheres, research on fate of
heterogeneous secondary nanoscale plastics that closely resemble the nanoplastics in nature is
limited. Moreover, polypropylene (PP) is one of the most widely used plastic types with a low
specific gravity. However, fate and transport of polypropylene secondary nanoscale plastics are
still unexplored. The first objective of this research is to characterize the polypropylene
secondary nanoscale plastics by measuring their hydrodynamic diameter and surface charge by
varying different parameters such as pH, ionic strengths, salt types, and natural organic matter
(NOM) concentrations. The results show that the surface charge of polypropylene secondary
nanoscale plastics increases with pH. The critical coagulation concentration (CCC) was also
determined in the presence and absence of NOM. Results show that the CCC values of PP
secondary nanoscale plastics for NaCl, MgCl2, and CaCl2 are 500 mM, 35 mM, and 20 mM,
respectively, higher than the CCC values of polyethylene (80 mM NaCl, 3 mM MgCl2, 0.1 mM
CaCl2) and polystyrene (800 mM NaCl, 25 mM MgCl2, 10 mM CaCl2) nanoplastics. When
NOM is present in water, the adsorbed NOM causes steric repulsion and makes the particles
more stable. The second objective of the research is to investigate the interactions of PP
secondary nanoscale plastics with bare silica and NOM coated surfaces and observe their
deposition and remobilization. Results suggest that PP secondary nanoscale plastics are more
mobile on silica surfaces than NOM coated surfaces. Their deposition and remobilization are
governed by the presence of NOM coated surfaces and divalent cations since they are ubiquitous
in nature. This study indicates that significant transport of PP secondary nanoplastics will be
possible in natural waters, and destabilization of these nanoplastics will be difficult.
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Details
- Title
- FATE AND TRANSPORT OF SECONDARY NANOSCALE PLASTICS IN THE AQUATIC ENVIRONMENT
- Creators
- Tahsin Md Zahid
- Contributors
- Indranil Chowdhury (Advisor)Courtney Gardner (Committee Member)Amanda Hohner (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Civil and Environmental Engineering
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 120
- Identifiers
- 99900883136301842
- Language
- English
- Resource Type
- Thesis