Aplicação da teoria do funcional da densidade (DFT) e da teoria quântica de átomos em moléculas (QTAIM) no entendimento da oxidação anódica de poluentes promovida pelo ânodo de diamante dopado com boro (BDD)
In environmental electrochemistry there is a focus on effluent decontamination using catalytic techniques and materials that promote the oxidation / mineralization of organic matter present in the effluent. The electrochemistry applied in this context is a treatment that fits in green chemistry,...
में बचाया:
| मुख्य लेखक: | |
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| अन्य लेखक: | |
| स्वरूप: | doctoralThesis |
| भाषा: | pt_BR |
| प्रकाशित: |
Brasil
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| विषय: | |
| ऑनलाइन पहुंच: | https://repositorio.ufrn.br/jspui/handle/123456789/28993 |
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| सारांश: | In environmental electrochemistry there is a focus on effluent decontamination using
catalytic techniques and materials that promote the oxidation / mineralization of organic
matter present in the effluent. The electrochemistry applied in this context is a
treatment that fits in green chemistry, as it avoids the use of environmentally
aggressive reagents. The chemical complexity surrounding the oxidation of pollutant
molecules is studied in the literature step by step in order to understand and improve
processes at the molecular level. In order to better understand at molecular level these
reaction processes, computational studies applied with collaborations from the areas
of environmental electrochemistry and theoretical chemistry to contribute to the
literature. Using the results of the electroanalytical techniques: cyclic voltammetry (CV)
and differentiated pulse voltammetry (DPV) were applied to the system with caffeine,
H2SO4 support electrolyte and boron-doped diamond anode (BDD). The
electroanalytical profile presented for this system resulted in an oxidative peak that
characterizes caffeine oxidation as a direct oxidation, in other words, a peak that occurs
before water discharge potential, indicating that caffeine oxidation occurs directly on
the surface of the BDD. From the information provided by the experimental
measurements of CV and PDV, a BDD surface cluster was computationally
constructed to verify caffeine-electrode interactions, obtaining energy parameters and
interaction points by Density Functional Theory (DFT) calculations, Quantum Theory
of Atoms in Molecules (QTAIM) and Electronic Localization Function (ELF). According
to the energy analysis results obtained from the DFT, the most and least stable
geometries were determined by interaction energy (IE). Topological data of interaction
geometries were obtained using QTAIM and ELF to verify the influences that occurred
during the interaction and to correlate with IE. In another system that treats anodic
oxidation as a more active scenario using BDD to mineralize pollutant, Eriochrome
Black T (EBT) in solution in the presence of Mg2+ and Ca2+ cations. Batch electrooxidation and monitoring the decontamination by Chemical Oxygen Demand (COD)
and Visible Ultraviolet Spectroscopy (UV-VIS), the behavior observed was the opposite
of what was reported in the literature when the treatment used was electro-fenton. In
this scenario, use of DFT to obtain the structures of the complexes formed between
EBT and cations, and then QTAIM calculations applied to the complexes, in order to
analyze the metal-ligand bonds in the structure of the adult complexes formed. The
electron density in these bonds reveals the strength of the complexes, so that it was
possible to compare the order of ease in undergoing electro-oxidation among the
complexes formed, this order of ease took into account complexes with tri and
hexavalent coordination sphere, for both. The coordinating sphere complexes did not
change the results. |
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