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Authors
Abstract(s)
A contaminação do ambiente por poluentes do tipo produtos farmacêuticos e de cuidado pessoal é um dos maiores problemas modernos que necessita de uma solução. Um tipo de metodologia promissora é a remoção deste tipo de poluentes através de fotodegradação com a ajuda de catalisadores.
Neste trabalho foram sintetizados oito fotocatalisadores inofensivos para o ambiente, baseados em pontos de carbono (Cdots) preparados a partir de águas residuais do processamento industrial do azeite, e suportados em sólidos inócuos (e.g. sílica e aluminas).
Após caracterização destes compósitos, estes foram testadas na fotodegradação catalítica da cafeína, um poluente modelo típico.
Os compósitos fotocatalíticos foram sintetizados por 2 métodos, sendo um o tratamento hidrotérmico de águas residuais do processamento industrial do azeite como precursor dos Cdots, na presença dos suportes de sílica ou aluminas, durante 4 h a 250 °C, com etilenodiamina usada como aditivo. Alternativamente, a síntese foi feita por mistura dos suportes com os Cdots previamente preparados.
Os compósitos foram caracterizados do ponto de vista estrutural, morfológico e ótico e os testes como fotocatalisadores para a degradação de cafeína foram realizados sob condições de radiação UV-Vis.
Um compósito em que o tratamento hidrotérmico foi feito já na presença de sílica foi o melhor fotocatalisador, com completa remoção da cafeína (20 ppm/150 mL) após 60 min de irradiação. Tendo em conta que a fotólise não foi capaz de degradar a cafeína na totalidade após 120 min de irradiação, consideráveis melhoramentos na fotodegradação deste tipo de poluentes foram atingidos através do uso destes materiais catalíticos. Este fotocatalisador foi ainda reutilizado 4 vezes, sem perdas de atividade, tendo-se demonstrado excelente para
reutilizações sucessivas.
The contamination of the environment by pharmaceutical and personal care products is a major concern needing a solution in the modern world. A type of promising methodology is the removal of this type of pollutants through photodegradation with the assistance of catalysts. In this work eight environmentally friendly photocatalysts based on carbon dots (Cdots) were synthesized from olive mill waste waters and anchored on harmless solid supports (e.g. silica and alumina). After characterization, these composites were tested in the catalytic photodegradation of caffeine, a well-known model pollutant.The photocatalytic samples were made by 2 methods, one being the hydrothermal treatment using olive mill waste waters as carbon dots green precursor, in the presence of silica or alumina, for 4 h at 250 °C, with ethylenediamine used as an additive. Alternatively, the synthesis was made by mixing the supports with the Cdots prepared previously without the presence of these supports.The composites were characterized from a structural, morphological, and optical point of view and their use as a photocatalyst for caffeine degradation was tested under UV-vis radiation conditions. A composite where the hydrothermal treatment was done already in presence of silica was the best photocatalyst, with the complete caffeine photocatalytic degradation (20 ppm/150 mL) being achieved within 1 hour of irradiation. Considering that photolysis was not able to completely degrade caffeine after 120 min of light irradiation, considerable improvements on the degradation of such pollutant were achieved by these catalytic materials. This photocatalyst was also reused 4 times without loss of activity, having thus proven itself as excellent for consecutive reutilizations.
The contamination of the environment by pharmaceutical and personal care products is a major concern needing a solution in the modern world. A type of promising methodology is the removal of this type of pollutants through photodegradation with the assistance of catalysts. In this work eight environmentally friendly photocatalysts based on carbon dots (Cdots) were synthesized from olive mill waste waters and anchored on harmless solid supports (e.g. silica and alumina). After characterization, these composites were tested in the catalytic photodegradation of caffeine, a well-known model pollutant.The photocatalytic samples were made by 2 methods, one being the hydrothermal treatment using olive mill waste waters as carbon dots green precursor, in the presence of silica or alumina, for 4 h at 250 °C, with ethylenediamine used as an additive. Alternatively, the synthesis was made by mixing the supports with the Cdots prepared previously without the presence of these supports.The composites were characterized from a structural, morphological, and optical point of view and their use as a photocatalyst for caffeine degradation was tested under UV-vis radiation conditions. A composite where the hydrothermal treatment was done already in presence of silica was the best photocatalyst, with the complete caffeine photocatalytic degradation (20 ppm/150 mL) being achieved within 1 hour of irradiation. Considering that photolysis was not able to completely degrade caffeine after 120 min of light irradiation, considerable improvements on the degradation of such pollutant were achieved by these catalytic materials. This photocatalyst was also reused 4 times without loss of activity, having thus proven itself as excellent for consecutive reutilizations.
Description
Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica
Keywords
Fotocatálise Pontos de carbono (Cdots) Sílica (SiO2) Gama-alumina (γ-Al2O3) Boemita (AlO(OH)) Compósitos fotocatalíticos Produtos farmacêuticos e de cuidado pessoal (PPCPs) Águas residuais do processamento industrial do azeite (ARPIA) Photocatalysis Carbon dots (Cdots) Silica (SiO2) Gama-alumina (γ-Al2O3) Boehmite (AlO(OH)) Photocatalytic composites Pharmaceutical and personal care products (PPCPs) Olive mill waste waters (OMWW)
Citation
CATALÃO, Gonçalo Jorge Sousa – Síntese de novos nanocompósitos de pontos de carbono e sua aplicação na fotodegradação de poluentes. Lisboa: Instituto Superior de Engenharia de Lisboa, 2021. Dissertação de Mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa