Development of a laser-based treatment and monitoring strategies of microplastics for water purification

Date

2025-8-28

Author

Moazzamia, Hafsa

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In this study, femtosecond laser irradiation achieved detectable microplastic degradation down to 2 fM concentrations, with a maximum observed decrease of 42% in the original number density, demonstrating the potential of ultrafast laser treatment for highly dilute systems. Microplastic pollution, first reported over five decades ago, continues to escalate and pose serious risks to marine, freshwater, and terrestrial ecosystems. While numerous detection, removal, and decomposition techniques have been explored, each faces limitations, underscoring the need for more effective and broadly applicable solutions. This study investigates laser-induced degradation of microplastics in aqueous environments under controlled laboratory conditions. Polystyrene microspheres suspended in water were used as a model microplastic. Samples were exposed to three laser sources: a visible millisecond-pulsed laser, a near-infrared nanosecond-pulsed laser, and a femtosecond-pulsed infrared laser, chosen to probe wavelength- and intensity-dependent multiphoton absorption phenomena contributing to polymer breakdown. Following treatment, samples were analyzed using an angular-resolved scattering setup to detect morphological or compositional changes. This optical method provides a sensitive approach to monitor structural alterations and ensures consistent measurement through calibrated power control. The results demonstrate the feasibility of using femtosecond lasers for degradation at extremely low concentrations, establish a comparative framework across laser regimes, and support the integration of light-based methods into future environmental remediation strategies.

Subject Keywords

Polystyrene, Environmental Remediation, Laser Treatment, Mie Scattering, Light-Matter interaction

URI

https://hdl.handle.net/11511/115631

Collections

Graduate School of Natural and Applied Sciences, Thesis