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Título: CARBON NANOPARTICLES FROM 2-AMINOPHENOL: SYNTHESIS, CHARACTERIZATION AND ADSORPTION STUDY
Autor: RAPHAEL FREIRE DA SILVA
Colaborador(es): VOLODYMYR ZAITSEV - Orientador
ALBINA MIKHRALIIEVA - Coorientador
Catalogação: 17/MAI/2022 Língua(s): PORTUGUESE - BRAZIL
Tipo: TEXT Subtipo: THESIS
Notas: [pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio.
[en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio.
Referência(s): [pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=59040&idi=1
[en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=59040&idi=2
DOI: https://doi.org/10.17771/PUCRio.acad.59040
Resumo:
Fluorescent nanoparticles are a very new and fascinating class of compounds. Among these are the semiconductors quantum dots (quantum confinement nanoparticles - QD) and also the new types of nanoparticles that are generally called carbon dots, CD (carbon based quantum confinement nanoparticles). Fluorescent nanoparticles can have several uses, particularly in chemical analysis: as sensors and in biotechnology for drug delivery and theranostics. Unlike QD semiconductors that have toxic metals in their core, carbono nanoparticles do not contain toxic components, being biologically beneficial and biodegradable. CDs have a very high surface area (up to 3600 m2/g) with various functional groups and can be used for immobilization on the surface of a support. Due to their functional groups, optical properties of CDs can be changed depending on the chemical environment, a notable feature of CDs in sensor applications. CDs form very stable suspensions in aqueous media and can be synthesized from molecular compounds such as sucrose, glucose, urea, citric acid and so on. It is worth noting that physicochemical and optical properties of CDs depend on their precursors. The aim of this work is to explore the use of aminophenol as a precursor in the synthesis of CDs via hydrothermal solvolysis to achieve red photoluminescence of the obtained nanomaterials; carrying out the purification of synthesized nanomaterials, at its limit; perform the morphological and structural characterization of the obtained carbon dots, through different physicochemical techniques, evaluating their photoluminescent properties; to develop the methodology of covalent immobilization of CDs on the surface of mesoporous silica gel, and to study the hybrid material as adsorbent. Atomic Force Microscopy images indicate particles between 1.0 to 7.0 nm depending on the solvent, as smaller particles appear better dispersibility in less polar solvents. The UVVis and Fluorescence spectra confirm the presence of CDs with pi-pi asterisk transitions at 290 nm in ethyl acetate and at 278 nm in heptane, they also indicate a bathochromic shift with the emission peak going from 501 nm to 535 nm with a solvent change, which can be used to assess local polarity, eg in biopolymers. Adsorption was verified using various silica-gel supports (Octadecyl, Mercaptopropyl, Aminopropyl and SiO2) indicating greater affinity with aminopropylsilica-gel, indicating a second-order kinetic process under the Langmuir model. It has been shown that the thermal treatment of aminopropyl-silica (SiO2-NH2) with adsorbed CDs leads to covalent immobilization of CDs to the support surface. This hybrid material (SiO2-NH2/CDs) could exhibit adsorption properties for metals and polyaromatic compounds. Therefore, the adsorption of a mixture containing 23 metals ions on SiO2-NH2/CDs was studied. The effect of the acidity of the medium on ion sorption was studied. It has been shown that ions with affinity for oxygenated ligands (such as Bi, Tl, Cr, Al, Fe) are better collected.
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