| Popis: |
Contaminants of emerging concern (CECs), including microplastics (MPs), in aquatic systems are recognized as potentially harmful to human health and the environment. Atmospheric conditions cause aging of MPs, resulting in surface and structural changes in material. Pristine MPs in water pose a certain risk on their own, but even worse MPs show the ability to interact with co-pollutants in water, behaving as vectors for other pollutants. Both aging of MPs and sorption of co-pollutants on MPs can completely alter MPs environmental behavior and toxicity. Potassium ferrate, K2FeO4, a strong oxidant and coagulant stands out as a potentially great candidate for removal of MPs from water. The main drawback is a narrow interval of pH values where the spontaneous K2FeO4 reduction is the lowest and oxidation activity towards MPs highest. The aim of this work was to investigate optimal pH conditions K2FeO4 towards MP removal and correlate these conditions with toxicity to the freshwater planktonic crustacean Daphnia magna and the green algae Selenastrum capricornutum (Pseudokirchneriella subcapitata). For that purpose, a Britton-Robinson buffer was prepared and the stability and activity of K2FeO4 were examined by UV-visible spectroscopy, at different pH values: 4, 7, and 10. Poly(ethylene terephthalate) (PET) in the form of shredded bottles and commercial foils were aged under ultraviolet radiation were used as representative sample of MPs. Oxidative effect experiments of K2FeO4 on UV-aged PET films were carried out during 180 min, by stepwise addition of K2FeO4, followed by quantification of K2FeO4 removal by coagulation and toxicity experiments. Acute toxicity bioassays were performed according to the standard procedures using Daphnia magna, (ISO 6341:2012) and Selenastrum capricornutum (Pseudokirchneriella subcapitata), (ISO 8692:2012). |
