Síntese verde de nanopartículas de prata e ouro e sua aplicação na determinação de mercúrio

• Ano de defesa: 2018
• Autor(a) principal: Lopes, Carla Regina Borges [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo
• Palavras-chave em Português: Metal nanoparticles; Green synthesis; Mercury sensor; Photoreduction; Mimusops Coriacea; Nanopartículas metálicas; Síntese verde; Sensor de mercúrio; Fotorredução
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=6371459; https://repositorio.unifesp.br/handle/11600/52797

Metal nanoparticles (MNP) has attracted great interest from the scientific community in recent years due to its large number of applications in various areas of science. In the environmental area, they stand out as an alternative to the traditional methods of quantification of pollutants, among them potentially toxic metals, such as mercury (Hg), which at high concentrations can cause damage to the brain, heart, kidneys, lungs and the immune system from human beings. The techniques traditionally used for the synthesis of metallic nanoparticles, involve the use of toxic chemical reagents, increasing the search for safer methods, among them, the green synthesis process has shown a sustainable alternative, it aims to use biological organisms to replace chemical reagents. In this project were synthesized spherical nanoparticles of silver (AgNP) and gold (AuNP) with average diameters between 10 and 50nm approximately. As reducing agents of the metallic ions and to avoid the aggregation of particles, the amino acid L-tryptophan (TrpAgNP/TrpAuNP) combined with exposure to the xenon lamp in a photoreduction process, or the aqueous extract obtained from leaves of Mimusops coriacea (McAgNP/McAuNP), plant of African origin with abundant presence on the coast of São Paulo, known as Abricó-de-Praia. Synthesized nanoparticles were characterized by different techniques, such as UV-vis optical absorption; emission (fluorescence); infrared (FTIR); transmission electron microscopy (TEM); dynamic light scattering (DLS) and zeta potential. Variations in the pH of the medium, concentration of the reagents and time of exposure to the lamp, were applied, aiming to optimize the synthesis processes, considering ideals that resulted in spherical nanoparticles with good stability, considering various parameters, such as: reagents and energy savings; lower cost; speed and yield. The synthesized nanoparticles have been tested for their potential for the detection and quantification of mercury in aqueous solution, through changes in the Superficial Plasmon of Resonance (SPR), with consequent alteration in the band of UV-vis optical absorption in the presence of different metal concentrations. The McAgNP presented the best result, with detection limit (LOD) from 6,5ng. mL -1, and quantification (LOQ) of 21,7ng. mL-1, showing high potential for the development of a simple and easy-to-operate method for the quantification of mercury. All the stages of this work were carried out so that the AgNPs/AuNPs obtained by these routes consisted of a material of interest in the development of new nanotechnological products with sustainable bases. The synthesis processes presented high reproducibility and are in accordance with the principles of green chemistry and sustainability, presenting as a low-cost alternative and biocompatible in the synthesis of AgNPs/AuNPs.