Tackling Nanoplastics in Aquatic Environments: Developing Valuable Reference Standards for Real-Time Detection and Remediation

The widespread use of petroleum-based plastic products has profoundly shaped modern life, introducing an era of "throwaway living" defined by convenience and disposability. However, the persistent nature of plastic waste has evolved into a critical environmental issue, with plastic debris accumulating across terrestrial, aquatic, and atmospheric ecosystems at alarming rates. Research has revealed that plastics degrade into smaller particles, including microplastics (MPs) (5 mm–1 µm) and nanoplastics (NPs) (<1 µm), which are now detected in oceans, farmlands, mountains, food, beverages, and even living organisms, creating new types of environmental pollutants. In response to environmental challenges caused by petroleum-based plastic pollution, society is increasingly adopting bio-based plastics derived from renewable sources. Poly(lactic acid) (PLA) is considered the most widely used bioplastic in real-life applications due to its thermoformability, low cost, and industrial compostability. However, if discarded, PLA does not fully degrade under natural environmental conditions and follows a similar pathway of conventional plastics, breaking down into MPs and NPs. This underscores the need to study the environmental fate and risks of such types of bio-based plastic alongside traditional plastics. Despite growing awareness of plastic pollution, current research on NPs remains limited mainly to conventional plastics, with several critical challenges hampering progress. These include the lack of environmentally relevant reference materials, especially for bio-based plastics leading to inaccurate representations of plastic types, and the absence of standardized methodologies, complicating cross-study comparisons. Analytical limitations further restrict the detection of smaller particles (<1 µm) at low concentrations. At the same time, the complex interactions between NPs and environmental matrices alter particle behavior, complicating their detection, characterization, and remediation. Addressing these challenges is essential to understanding and managing plastic pollution, particularly for bio-based plastics like PLA. This thesis focuses on tackling these pressing issues by developing integrated approaches to address the challenges of lack of reference materials, remediation, and detection of NPs. The work introduces a protocol for fabricating bio-based PLA NPs using the laser ablation method. This technique produces particles with properties like those anticipated in aquatic environments, providing a valuable reference model for studying environmental fate, ecological interactions, and remediation strategies. Subsequently, innovative approaches for remediating these environmentally relevant NPs in water using piezo-photocatalytic systems are explored, offering practical solutions for NP degradation in water without the requirement of high energy sources but just solar light irradiation and wave movements. The final section investigates advanced detection technologies, specifically Electrolyte-Gated Carbon Nanotube Field-Effect Transistor (EG-CNT-FET) sensors, demonstrating their ability to detect NPs, even with surface modifications, in complex environmental samples. This thesis emphasizes the critical importance of addressing the environmental impact of NPs through integrated strategies, combining realistic modeling, effective remediation, and advanced detection technologies. By focusing on bio-based plastics like PLA, this work provides a comprehensive framework for mitigating the environmental risks of plastic pollution and supporting the development of sustainable solutions for future challenges.