Search

Browse

• Communities
• Authors
• Year
• Titles
• Subjects

My Space

• Login

Κινητική αποδόμησης πλαστικών σφαιριδίων στο θαλάσσιο περιβάλλον

Dimopoulou Evgenia

Full record

---

Summary

The plastics industry is one of the fastest-growing industries in the world. No matter how much convenience the use of its products in everyday life has brought, their uncontrolled production, disposal and mismanagement pose catastrophic risks. The manufacturing philosophy of plastics is based from the outset on their maximum durability and lightness, resulting in their indestructibility. These properties make it easier for them to be transported and remain in the marine environment where they end up. There, they are exposed to many factors that contribute to their breakage, the formation of microplastics and nanoplastics, along with their gradual further degradation. Smaller plastics pose an even greater threat to ecosystems as their size makes them particularly easy to transport, be ingested by organisms, and enter the food chain. As a result, the research community is increasingly focusing on the aging processes and the complex mechanisms of their degradation, in a practical attempt by advanced science to contribute to the recovery of life-promoting values. In this thesis, attempts were made to study the kinetics that are being followed during the photodegradation and biodegradation of plastic pellets, as these constitute two of the main processes to which plastics are subjected in aquatic ecosystems. Apart from studying the mechanisms, it aimed to create a proposed model to predict the degradation rate. In the experiment whose data were used, pellets of high-density polyethylene (HDPE) and polypropylene (PP) were exposed to natural aging conditions in aquariums for six months. In order to study the degradation kinetics, six sets of equations including Schwarzschild’s law, Monod kinetics, sigmoid equations, and first-order kinetics were applied. According to the above equations, an attempt was made to fit the radiation data, the radius of the pellets and the carbonyl index (CI). The reasoning followed was based on the trial-and-error method, modifying and replacing the equations and/or parameters in each fitting attempt to approach the desired result. The degree of complexity, the amount of data, the degrees of freedom and the necessary assumptions are the potential factors influencing our continuous efforts. Unfortunately, as a result, the desired convergence was not achieved in any of the tests. We believe, however, that the direction taken was right since it focuses on the study of photodegradation and biodegradation processes, which act in parallel in the environment and directly influence the rate of each other. Moreover, we believe that, apart from the useful conclusions drawn, there were also valuable suggestions for wider investigation and, above all, for the search for more appropriate methods.

Available Files

Services