Detalhes bibliográficos
| Ano de defesa: |
2023 |
| Autor(a) principal: |
Muraro, Pâmela Cristine Ladwig |
| Orientador(a): |
Silva , William Leonardo da |
| Banca de defesa: |
Baldez , Raisi Natalia Lenz,
Brackmann , Rodrigo,
Machado, Alencar Kolinski,
Oliveira , Jivago Schumacher de |
| Tipo de documento: |
Tese
|
| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Franciscana
|
| Programa de Pós-Graduação: |
Programa de Pós-Graduação em Nanociências
|
| Departamento: |
Biociências e Nanomateriais
|
| País: |
Brasil
|
| Palavras-chave em Português: |
|
| Área do conhecimento CNPq: |
|
| Link de acesso: |
http://www.tede.universidadefranciscana.edu.br:8080/handle/UFN-BDTD/1202
|
Resumo: |
Contamination of wastewater by synthetic dyes s responsible for pollution and changes in the environment, as they directly modify biological cycles, affecting aquatic beings and impairing photosynthesis processes. The need for advanced treatment technologies, such as Advanced Oxidative Processes (AOPs) has been an alternative for wastewater treatment, with an emphasis on heterogeneous photocatalysis. In this context, the present work aims to biosynthesize, characterize and evaluate the photocatalytic activity of silver nanoparticles (AgNPs), titanium dioxide (TiO2-NPs) and silver and titanium bimetallic (Ag/TiNPs) for application in the removal of the Rhodamine B (RhB) dye, as well as antimicrobial activity and toxicity. For the synthesis of nanomaterials, the biosynthesis method was used from Aloe vera extract (as bioreducer) and titanium isopropoxide and silver nitrate, as metallic precursors. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM EDS/FEG-SEM), N2 porosimetry (BET/BJH method), Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy, diffuse reflectance spectroscopy (DRS) and zeta potential. The antimicrobial activity was carried out by the minimum inhibitory concentration (MIC) assay against 2 bacterial strains (S. aureus ATCC 25923 and P. aeruginosa ATCC 27853). Cell viability was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay for 293T (human embryonic kidney, ATCC CRL-3216), MDBK (bovine kidney, ATCC CCL-22) and HaCat (human keratinocyte, ATCC PCS-200-011TN), while the safety profile for VERO (monkey kidney ATCC CCL-81) and L929 (fibroblasts, ATCC CCL-1) cell lines. The central composite rotatable design (CCRD 23) was carried out to determine the ideal condition of the photocatalytic process. The photocatalysis tests were carried out in a batch regime for the degradation of the Rhodamine B dye (RhB) under visible radiation. For the ecotoxicity tests, Lactuca sativa, Cucumis sativus and Brassica oleracea seeds were used. XRD diffractograms indicated the presence of characteristic peaks of AgNPs, TiO2-NPs and Ag/TiNPs confirming the effectiveness of the synthesis method. In addition, metallic nanoparticles (NMPs) showed mesoporous characteristics, with a specific surface area between 6.09, 118 and 343 m² g-1 (AgNPs, TiO2-NPs and Ag/TiNPs, respectively), diameter 33.47, 9.2 and 4.9 nm and pore volume 0.032, 0.2 and 0.26 cm³ g-1, respectively. All samples showed negative charges (-35.3 mV for AgNPs, -4.90 mV for TiO2-NPs and -15.10 mV for Ag/TiNPs), indicating electrostatic compatibility with the cationic RhB dye. SEM micrographs of MNPs of the AgNPs did not show defined morphology, while for TiO2-NPs and Ag/TiNPs they indicated the presence of agglomerates. AgNPs showed antibacterial activity against the bacterial strains evaluated in 15.62 µg mL-1 for S. aureus and 7.81 µg mL-1 for P. aeruginosa, while the other MNPs did not show antimicrobial activity for the tested pathogens. Regarding the CCRD 2³, the ideal condition was [NMPs] = 3.5 g L-1, [RhB] = 10 mg L-1 and pH = 7.0, with a removal of 90% (k = 0.0146 min-1) for TiO2-NPs, and 100% (k = 0.029 min-1) for Ag/TiNPs. Regarding the reuse of MNPs, TiO2-NPs showed a small reduction to 84.67% (k = 0.0125 min-1 ) and Ag/TiNPs reduced to 95.37% (k = 0.0182 min-1) in degradation of RhB after 5 cycles. The effect of scavenger agents showed that octanol was responsible for capturing electrons when hydroxyl was released. For ecotoxicity tests, MNPs showed toxicity for all tested seeds. For the soil, XRD indicated the presence of NMPs, demonstrating toxicity against the inhibition of seed growth. For the MTT assays, the VERO and L929 lines did not show a decrease in cell viability for the NMPs tested. The generation of DCFHA, TiO2-NPs did not produce free radical formation, while AgNPs and Ag/TiNPs showed an increase in DCFHA in 50 and 100 µg mL-1. For NO generation, TiO2-NPs did not generate NO in all concentrations tested, while AgNPs and Ag/TiNPs showed an increase in nitrate and nitrites in 50 and 100 µg mL-1. Therefore, it was possible to biosynthesize, characterize and evaluate the antimicrobial activity and toxicity of metallic nanoparticles of titanium dioxide and/or silver, with potential properties for application in the removal of dyes from wastewater, meeting the theme of sustainable development with nanotechnology. |
