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| Author(s): |
João Victor Mattioni
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2024-10-04 |
| Examining board members: |
Henrique Eisi Toma;
Lucas Carvalho Veloso Rodrigues
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| Advisor: | Henrique Eisi Toma; Fernando Menegatti de Melo |
| Abstract | |
The chemical interactions between gold and iron oxide open doors to a wide range of possibilities, from the selective recovery of metals to the creation of advanced multifunctional materials. These interactions, which can range from the formation of simple chemical bonds to the construction of complex hierarchical structures, make it possible to combine the distinct properties of each component in new contexts. By deepening the study of these interactions, it seeks not only to understand the underlying mechanisms, but also to explore the potential for technological innovation that they offer. In Chapter 1, the interactions between gold and iron oxide were studied through magnetic nanohydrometallurgy, in which the coordination chemistry between the nanoparticles of these materials was explored in detail. Using iron oxide nanoparticles synthesized by alkaline coprecipitation, we investigated the capture of gold nanoparticles, stabilized by ranelate ions. Ranelate played an essential role in the formation of gold nanoparticles through the formation of direct bonds between gold and carbon, while also coordinating to the surface of iron oxide through its carboxylates. Depending on the experimental conditions, we observed that the interactions between the nanoparticles ranged from stable and permanent chemical coordinations to reversible electrostatic interactions, demonstrating the versatility and sensitivity of the system to synthesis conditions. In Chapter 2, the research advances to the development of new materials based on the interactions between gold and iron oxide, with emphasis on the synthesis of complex superstructures. In particular, the chapter addresses the Janus Magnetic Superparticles, which, inspired by the Roman god Janus, present a functional duality between their faces. They werebuilt using magnetic iron oxide nanoparticles, synthesized in different formats by thermodecomposition, which act as building blocks for the creation of superstructures, through controlled agglomeration in confined environments, such as surfactant micelles or spray droplets. By modulating the surface hydrophobicity of magnetic superparticles with increasing concentrations of sodium dodecyl sulfate, they were able to stabilize paraffin wax emulsions melted in water at different depths. Finally, the portion of iron oxide exposed to the aqueous phase is chemically modified with amine groups to facilitate the deposition and growth of metallic gold. This process results in the formation of Janus Magnetic Superparticles, which combine the magnetic properties of iron oxide with the optical and catalytic properties of gold. (AU) | |
| FAPESP's process: | 19/14771-5 - Development of superparamagnetic nanoparticles functionalized with complexing agents for the capture and exploitation of strategic metals |
| Grantee: | João Victor Mattioni |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |