A novel filtration model for microplastics using natural oils and its application to the environment

Abstract

There is an urgent need to extract microplastics from the ocean. Current research aimed toward physical separation of microplastics from water by developing a filter that allows water to pass but captures microplastics. But the physical microplastic filters are too small that they can only filter small amount of water. Our research utilized chemical ideas to devise an effective filtering method that can potentially filter the ocean. We hypothesized that if microplastic contaminated water is mixed with a nonpolar solvent with a freezing point higher than that of water, then the microplastics will be separated from the water. In our experiments, we used two types of nonpolar solvents, palm oil and palm kernel oil, and we evaluated extraction of the three most abundant types of microplastics in the ocean (polystyrene, polyethylene, and polypropylene). The highest microplastic extraction percentage was 96.2% when filtering 500 µm polystyrene with palm oil, and the lowest was 94.2% when filtering 13 µm polypropylene with palm kernel oil. In addition to measuring extraction efficiency, we designed and conducted an experiment to find the amount of energy required to liquefy palm oil and palm kernel oil. Our calculations suggest that palm kernel oil is more energy-efficient and produces less environmental concerns. Furthermore, we proposed a real-world application of the system, which sheds light on the viability of attacking the microplastic problem in the ocean. Calculations using the model showed that it would take an estimated 48.7 years to filter microplastics from the Pacific Ocean. Overall, the results of this study yield an elegant solution to a global environmental problem that poses a grave threat not only to humanity but also to the whole ecosystem.