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Abstract(s)
Nos dias de hoje, os desafios ambientais e a sustentabilidade são uma das grandes preocupações das Organizações Internacionais e dos decisores políticos, por isso, a poluição ambiental é cada vez mais uma questão vital e desafiadora para a humanidade. Nesse sentido, é essencial o desenvolvimento de tecnologias que permitam a minimização e eliminação desses poluentes. Assim, procedeu-se à síntese e caracterização de novas redes metalo-orgânicas (MOFs) e estruturas orgânicas covalentes (COFs) e, devido às suas propriedades físicas e químicas únicas, e à sua aplicação na adsorção de gases e de corantes. As redes metalo-orgânicas (MOFs) foram sintetizadas por reações hidrotérmicas e as respetivas estruturas cristalinas obtidas por evaporação lenta de solvente. As estruturas orgânicas covalentes (COFs) foram obtidas por reações hidrotérmicas a partir de material orgânico ligado por ligações covalentes. A estrutura e a estabilidade térmica dos MOFs e COFs foram determinadas recorrendo a diferentes técnicas de caracterização, nomeadamente análise termogravimétrica (TGA), espectroscopia de infravermelho com transformada de Fourier (FTIR-ATR), espectroscopia ultravioleta-visível (UV-VIS), ressonância magnética nuclear (RMN), microscopia eletrónica de varrimento (SEM) e método Brunauer, Emmett, Teller (BET). A capacidade de adsorção dos novos materiais híbridos porosos (MOFs e COFs) foi testada na adsorção de gases, sendo utilizado o metano (a 25 e 0 ºC), o dióxido de carbono (a 25 e 0 ºC) e o nitrogénio (a -196 ºC). Neste estudo, o MOF-2 e o COF-4 apresentaram as melhores performances com máximos de adsorção de 2,59 mmol/g e 2,38 mmol/g, respetivamente, utilizando-se o dióxido de carbono, à temperatura de 0ºC. Os estudos de adsorção de corantes com COFs foram realizados para seis corantes com propriedades físicas e químicas distintas, tendo os COF-1 e COF-3 apresentado os melhores resultados, nomeadamente no caso do azul de metileno com 97,6 e 92,3% de adsorção, respetivamente.
Nowadays, environmental challenges and sustainability are a major concern for International Organisations and policymakers, therefore, environmental pollution is< cx increasingly a vital and challenging issue for mankind. In this sense, it is essential to develop technologies that allow the minimization and elimination of these pollutants. Thus, the synthesis and characterization of new metal-organic networks (MOFs) and covalent organic frameworks (COFs) and, due to their unique physical and chemical properties, their application in gas and dye adsorption was carried out. The metal-organic networks (MOFs) were synthesized by hydrothermal reactions and their crystal structures were obtained by slow solvent evaporation. Covalent organic structures (COFs) were obtained by hydrothermal reactions from covalently bonded organic material. The structure and thermal stability of MOFs and COFs were determined using different characterization techniques, n,amely thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR-ATR), ultraviolet-visible spectroscopy (UV-VIS), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and Brunauer, Emmett, Teller (BET) method. The adsorption capacity of the new porous hybrid materials (MOFs and COFs) was tested on the adsorption of gases such as methane (at 25 and 0 ºC), carbon dioxide (at 25 and 0 ºC) and nitrogen (at -196 ºC). In this study, MOF-2 and COF-4 presented the best performances with a maximum adsorption of 2.59 mmol/g and 2.38 mmol/g, respectively, using carbon dioxide a temperature of 0ºC. The adsorption studies with COFs were carried out for six dyes with different physical and chemical properties. COF-1 and COF-3 presented the best results, namely for methylene blue with 97.6 and 92.3% of adsorption, respectively.
Nowadays, environmental challenges and sustainability are a major concern for International Organisations and policymakers, therefore, environmental pollution is< cx increasingly a vital and challenging issue for mankind. In this sense, it is essential to develop technologies that allow the minimization and elimination of these pollutants. Thus, the synthesis and characterization of new metal-organic networks (MOFs) and covalent organic frameworks (COFs) and, due to their unique physical and chemical properties, their application in gas and dye adsorption was carried out. The metal-organic networks (MOFs) were synthesized by hydrothermal reactions and their crystal structures were obtained by slow solvent evaporation. Covalent organic structures (COFs) were obtained by hydrothermal reactions from covalently bonded organic material. The structure and thermal stability of MOFs and COFs were determined using different characterization techniques, n,amely thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR-ATR), ultraviolet-visible spectroscopy (UV-VIS), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and Brunauer, Emmett, Teller (BET) method. The adsorption capacity of the new porous hybrid materials (MOFs and COFs) was tested on the adsorption of gases such as methane (at 25 and 0 ºC), carbon dioxide (at 25 and 0 ºC) and nitrogen (at -196 ºC). In this study, MOF-2 and COF-4 presented the best performances with a maximum adsorption of 2.59 mmol/g and 2.38 mmol/g, respectively, using carbon dioxide a temperature of 0ºC. The adsorption studies with COFs were carried out for six dyes with different physical and chemical properties. COF-1 and COF-3 presented the best results, namely for methylene blue with 97.6 and 92.3% of adsorption, respectively.
Description
Trabalho final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica
Keywords
Redes metalo-orgânicas Estruturas orgânicas covalentes Adsorção de gases Adsorção de corantes Metal-organic frameworks Covalent organic frameworks Gas adsorption Dye adsorption
Citation
SANTOS, Andreia Alexandra Cerqueira dos - Desenvolvimento de novas estruturas orgânicas metálicas (MOFs) e estruturas orgânicas covalentes (COFs) para a remoção de poluentes ambientais tóxicos. Lisboa: Instituto Superior de Engenharia de Lisboa, 2022. Dissertação de Mestrado