DUGi

Avaluació de la capacitat de tractaments terciaris d’aigües residuals basats en Daphnia magna per filtrar nanopartícules metàl·liques en condicions controlades i en presència de microplàstics : estudis de laboratori

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@26265

At present, the increase in the nanotechnology industry has led to a rise in the use of nanoparticles (NPs). These have very interesting properties that allow for applications in different sectors, such as medical, technological, and energy. In this case, we will focus the study on silver nanoparticles (AgNPs), highly used in the medical industry thanks to their antibacterial properties, and titanium oxide nanoparticles (TiO2NPs), with important applications in daily consumer products. These nanoparticles, like microplastics, accumulate excessively in ecosystems, causing a negative effect on the life forms present in them. Regarding the 1960s and 1970s, the mass use of plastics experienced significant expansion due to the increased production of plastic products. As a result, ecosystems have suffered an uncontrolled rise in waste, leading to the accumulation of MP, negatively affecting the fauna and flora of the ecosystems. This study examines the effect of NPs and MPs in the presence of Daphnia magna (D. magna). D. magna is a small crustacean capable of ingesting or eliminating small particles that do not precipitate in secondary sedimentation tanks. For this reason, laboratory studies are conducted to simultaneously assess the toxicity of NPs and the presence of MP in D. magna, as well as to determine the metal absorption capacity of these organisms. AgNPs, TiO2NPs, and polyethylene MP were used in the various experiments. Studies were conducted on the stability of NPs in different concentrations of humic acids and surfactants, as well as working with NPs of different sizes and coatings to determine their behavior and evaluate the effect caused by the presence of D. magna. First, it was determined that D. magna is capable of surviving for a certain period under stress conditions and assimilating some of the present metal. It is important that the presence of MP negatively affects survival. Additionally, glass wool was established as the most adequate filtration method among those evaluated for nanoparticle suspensions. Finally, in scanning electron microscope (SEM) studies, the presence of AgNPs in the solutions was verified after 72 hours under typical laboratory conditions and in the presence of light, although they appear to be aggregated. As for TiO2NPs, it was found that after 72 hours, there are no nanoparticles present, corroborating previous results obtained by ICP-MS, where a similar behavior between ionic titanium and TiO2NPs was observed

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