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Título: FUNDAMENTAL ASPECTS OF BORON REMOVAL FROM WASTEWATERS BY ELECTROCOAGULATION METHOD
Autor: THIAGO DA SILVA RIBEIRO
Colaborador(es): MAURICIO LEONARDO TOREM - Orientador
ANTONIO GUTIERREZ MERMA - Coorientador
Catalogação: 01/FEV/2019 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=36398&idi=1
[en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=36398&idi=2
DOI: https://doi.org/10.17771/PUCRio.acad.36398
Resumo:
Boron compounds are used in the metallurgical industry, microelectronics, glassware, agriculture, etc. This element is an essential micronutrient in the development of microorganisms, plants, animals and humans. However, it can be toxic in high concentrations and therefore needs to be removed from water and effluent. In Brazil, the standard limit is 0.5mg/L for Class I and II freshwaters, established by Conama Resolution 357/2005. In turn, the Conama 430/2011 resolution establishes an effluent discharge standard of 5mg/L. The present dissertation aims to study the removal of boron by electrocoagulation for the treatment of water and effluents containing boron, using a cell with an arrangement of 4 monopolar aluminum electrodes (2 cathodes and 2 anodes) in parallel. The results show that the electrocoagulation process is a viable alternative for the removal of boron and reaches efficiencies around 70 per cent (at initial pH equals to 4, current density equals to 18.75mA/cm2 and electrolysis time equals to 90min). The kinetic model that best describes the removal of boron was pseudo-first order. The Langmuir model fitted very well to the experimental data obtained. The value of qm obtained by the Langmuir model reflected the high maximum adsorption capacity (qm equals to 334mg/g). Through the analysis by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) on the surface of the electrodes, it was observed the presence of pitting corrosion in the cathodes and uniform corrosion in the anodes. The morphology of the sludge produced in the electrocoagulation process was analyzed by SEM, indicating the presence of a heterogeneous surface morphology, while the X-ray diffraction (XRD) analysis showed broad peaks characteristic of an amorphous material and the predominant aluminum phase was boehmite, AlO(OH), finally, through the Electron Energy Loss Spectroscopy (EELS) analysis, it was possible to detect boron in the sludge, as well as aluminum and oxygen. In view of the results obtained in the optimization study from the Response Surface Methodology (RSM), it was verified that the development of a mathematical model by regression analysis made possible the evaluation of the effect of the independent variables (current density, initial pH and time of electrolysis) and their interactions in the removal of boron.
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