A SÍNTESE VERDE DE NANOPARTÍCULAS METÁLICAS COMO UMA PRÁTICA DE ENSINO

• Autor(a) principal: Schram, Marcelo
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do UNICENTRO
• Texto Completo: http://tede.unicentro.br:8080/jspui/handle/jspui/1700
• topic: ensino de nanotecnologia; nanotecnologia; nanopartículas metálicas; síntese verde; nanotechnology teaching; nanotechnology; metallic nanoparticles; green synthesis; CIENCIAS EXATAS E DA TERRA::QUIMICA

The master’s thesis that is here presented has the green synthesis of nanoparticles as a form of methodology for the teaching of nanoscience and nanotechnology as focus. Initially the synthesis of metallic nanoparticles was studied through the vegetable extract of pine nut shells as a reducing and stabilizing agent, viewing to promote the substitution of the traditional reagents used in the synthesis of these nanoparticles. The synthesis of silver and gold nanoparticles was performed, therefore, through phenolic compounds extracted from raw and cooked pine nut shells. The characterization of the nanoparticles through UV-Vis spectrophotometry and dynamic light scattering proved the formation of the gold and silver nanoparticles in a nanometer dimension, allowing a glimpse of the possibility of using the aqueous extract of the pine nut shell as a reducing agent in the process of green synthesis. In the same way, analysis of zeta potential proved that the phenolic compounds extracted from the pine nut shells stabilized the synthesized nanoparticles, evidencing that the vegetable extract plays a double role in green synthesis, as a reducing agent and, at the same time, as a stabilizing agent. Additionally, an explanatory study was developed viewing to comprehend the influence of the experimental parameters involved in green synthesis, testing: the influence of the concentration of the precursor, of the vegetable extract and of the volumetric proportion between precursor and vegetable extract. The effect of modifications in the hydrogen potential (pH), in temperature and time of synthesis was also evaluated. In a general sense, the study allowed us to elucidate how the experimental parameters mentioned can be incorporated in green synthesis of metallic nanoparticles. Founded in the adopted process, we proceeded to the evaluation of the green synthesis of metallic nanoparticles through holistic metrics of green chemistry, specifically the green star and the green matrix. The referred evaluation demonstrated the degree of chemical greenery in green synthesis, that is, it made the way that green synthesis meets the principles of green chemistry evident, besides exposing possibilities of changes in the pursuit of the increase of global greenery in the procedure. Lastly, the methodology of green synthesis was transposed into the shape of a didactic experiment and was made available in the form of an experimental script that can be consulted in approaches of the theme in an educational context. Additionally, experiments that illustrate the specific properties of the silver and gold nanoparticles, specifically, and the nanometer scale properties, in a general way, were developed and/or adapted and tested, having been made available at the end of this dissertation. Approaching green synthesis of metallic nanoparticles as a teaching practice of nanoscience and nanotechnology, this thesis comes to form in the shape of a set of experiments destined to investigate and comprehend specific properties of some nanoparticles and of the nanometer scale. This way, the green synthesis of metallic nanoparticles is made available to those that set out to promote nanoscience and nanotechnology approaches in a safe, accessible and environmentally friendlier way, as this research aspired.