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Microplásticos e outros poluentes em ambiente aquático: estudo de interações e novas estratégias de remoção
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Abstract(s)
O presente trabalho teve como objetivo avaliar a eficiência de remoção de MPs de
águas recorrendo a nanopartículas magnéticas de ferro (MNPs). Foram testados 4 tipos
de MPs, Poliamida – Nylon 6 (PA6) de 15-20 μm, Politetrafluoretileno (PTFE) de 20 μm,
Politetrafluoretileno (PTFE) de 6-9 μm e Polimetilmetacrilato (PMMA) de 15 μm. Foi
também estudado o efeito da modificação das MNPs ao nível das camadas adjacentes
(Fe3O4MNPs - partículas A1 e B1; Fe3O4MNPs@TEOS - A2 e B2; e
Fe3O4MNPs@TEOS@MPS - A3 e B3) e dos tempos de síntese (1 h - partículas A e 30
min - partículas B).
Foi feita a caracterização por espectroscopia de infravermelho por transformada de
Fourier (FTIR) dos MPs virgens e das MNPs antes e após os ensaios. Foram também
analisadas algumas das MNPs por microscopia eletrónica de varrimento (SEM) e por
microscopia eletrónica de transmissão (TEM). Através dos espectros de FTIR foi possível
identificar os grupos funcionais que compõem tanto os MPs como as MNPs, pelas
imagens de SEM foi possível aferir a forma das MNPs e pelas análises TEM foi avaliado
o respetivo tamanho.
Nos ensaios realizados foi possível verificar que a composição das camadas das MNPs
influenciam a eficiência de remoção obtida, principalmente pelo tipo de interações que
estabelecem com os MPs, tendo sido possível identificar a existência de interações
hidrofóbicas entre duas das nanopartículas e o PTFE. Outros fatores, como o tamanho das
MNPs e as respetivas concentrações, foram estudados, observando-se que a influência do
tamanho das MNPs depende do MP e que no geral para a concentração de 1 g/L foram
obtidas percentagens de remoção superiores do que para 0,5 g/L.
As percentagens de remoção obtidas encontram-se na gama 31,4 - 54,4 %, para o PA6
(dimensão 15-20 μm), 94,3 - 95,2 % para o PTFE (dimensão de 20 μm), 76,4 - 93,9 %
para o PTFE (dimensão 6-9 μm) e 55,0 - 85,8 % para o PMMA (dimensão de 15 μm).
Water quality is directly related to the presence of pollutants. Micropollutants, including microplastics (MPs), are a current environmental concern, and it is therefore necessary to find new sustainable treatments to remove these substances from wastewater. The present study aimed to evaluate the efficiency of MPs removal from water using magnetic iron nanoparticles (MNPs). Four types of MPs were tested: Polyamide-Nylon 6 (PA6) of 15-20 μm, Polytetrafluoroethylene (PTFE) of 20 μm, Polytetrafluoroethylene (PTFE) of 6-9 μm and Polymethylmethacrylate (PMMA) of 15 μm. The effect of the modification of MNPs at the level of adjacent layers (Fe3O4MNPs - particles A1 and B1; Fe3O4MNPs@TEOS - A2 and B2; and Fe3O4MNPs@TEOS@MPS - A3 and B3) and synthesis times (1 h - particles A and 30 min - particles B) was also studied. Fourier transform infrared spectroscopy (FTIR) characterization of the virgin MPs and MNPs was performed before and after the tests. Some of the MNPs were also analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using the FTIR spectra, it was possible to identify the functional groups that make up both the MPs and the MNPs, using the SEM images, it was possible to measure the shape of the MNPs, and using TEM analyses, their size was evaluated. In the tests performed, it was possible to verify that the composition of the MNP layers influences the removal efficiency obtained, mainly due to the type of interactions they establish with the MPs, and it was possible to identify the existence of hydrophobic interactions between two of the nanoparticles and the PTFE. Other factors, such as the size of the MNPs and their respective concentrations, were studied, observing that the influence of the size of the MNPs depends on the MP and that, in general, higher removal percentages were obtained for the concentration of 1 g/L than for 0.5 g/L. The removal percentages obtained are in the range 31.4 - 54.4 % for PA6 (size 15-20 μm), 94.3 - 95.2 % for PTFE (size 20 μm), 76.4 - 93.9 % for PTFE (size 6-9 μm) and 55.0 - 85.8 % for PMMA (size 15 μm).
Water quality is directly related to the presence of pollutants. Micropollutants, including microplastics (MPs), are a current environmental concern, and it is therefore necessary to find new sustainable treatments to remove these substances from wastewater. The present study aimed to evaluate the efficiency of MPs removal from water using magnetic iron nanoparticles (MNPs). Four types of MPs were tested: Polyamide-Nylon 6 (PA6) of 15-20 μm, Polytetrafluoroethylene (PTFE) of 20 μm, Polytetrafluoroethylene (PTFE) of 6-9 μm and Polymethylmethacrylate (PMMA) of 15 μm. The effect of the modification of MNPs at the level of adjacent layers (Fe3O4MNPs - particles A1 and B1; Fe3O4MNPs@TEOS - A2 and B2; and Fe3O4MNPs@TEOS@MPS - A3 and B3) and synthesis times (1 h - particles A and 30 min - particles B) was also studied. Fourier transform infrared spectroscopy (FTIR) characterization of the virgin MPs and MNPs was performed before and after the tests. Some of the MNPs were also analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using the FTIR spectra, it was possible to identify the functional groups that make up both the MPs and the MNPs, using the SEM images, it was possible to measure the shape of the MNPs, and using TEM analyses, their size was evaluated. In the tests performed, it was possible to verify that the composition of the MNP layers influences the removal efficiency obtained, mainly due to the type of interactions they establish with the MPs, and it was possible to identify the existence of hydrophobic interactions between two of the nanoparticles and the PTFE. Other factors, such as the size of the MNPs and their respective concentrations, were studied, observing that the influence of the size of the MNPs depends on the MP and that, in general, higher removal percentages were obtained for the concentration of 1 g/L than for 0.5 g/L. The removal percentages obtained are in the range 31.4 - 54.4 % for PA6 (size 15-20 μm), 94.3 - 95.2 % for PTFE (size 20 μm), 76.4 - 93.9 % for PTFE (size 6-9 μm) and 55.0 - 85.8 % for PMMA (size 15 μm).
Description
Keywords
Hydrophobic Interactions Magnetic Iron Nanoparticles Microplastics Water Água Interações hidrofóbicas Microplásticos Nanopartículas magnéticas de ferro