Synthesis of TiO2@MOF composites for the photodegradation of organic pollutants

• Autor(a) principal: Pedro Henrique Morais Andrade
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/38408; https://orcid.org/0000-0002-8264-1818
• topic: MOF; HKUST-1; MIL-100(Al); TiO2; Photocatalysis; NSAIDs; Ibuprofen; Diclofenac; Materiais; Ciência dos materiais; Diclofenaco; Dióxido de titânio; Fotocatálise

The contamination of ecosystems with toxic materials is a recurring problem in human history. Pollutants such as heavy metals, organic materials, industrial dyes, radioactive waste, and solvents are commonly found in various environments, causing harmful effects to humans and other species. The pharmaceuticals and personal care products (PPCPs) pose a specific concern due to its extensive use and incorrect disposal around the world, specifically the non-steroidal anti-inflammatory drugs (NSAIDs), with ibuprofen (IBP) and diclofenac (DIC) being on the top list. The use of materials with controlled pore structures is an effective strategy for both capturing and degrading these pollutants. Through adsorption and photocatalysis, these compounds can remove several toxic species present in soil, water, and atmosphere. This work evaluates the adsorption and degradation capacity of methylene blue (MB), IBP, and DIC using the metal-organic frameworks (MOFs) HKUST-1 and MIL-100(Al). The MOFs were synthesized through a hydrothermal treatment and later impregnated with titania, which is a well-established semiconductor worldwide due to its low cost and low toxicity coupled with a high photoactivity and chemical stability. TiO2 was produced by a sol-gel route without the presence of an acid, using the MOFs as a site for heterogeneous nucleation. In order to evaluate the influence of TiO2 nanoparticles in the MOFs over their photocatalytic activity, UV-vis kinetic studies were conducted, and the apparent first-order constant (Kapp) were calculated using the Langmuir-Hinshelwood (L-H) kinetic model. It was observed that aluminum trimesate withstood the modification step, and anatase nanoparticles were successfully anchored onto its surface and within its pore framework. This composite showed an improved capacity of degrading MB, IBP, and DIC under UVA illumination. Copper trimesate, on the other hand, showed a structural collapse during the modification step, probably due its fragility in water-rich media. However, the novel composite material experienced an increase in its photocatalytic activity compared to HKUST-1, due to the presence of crystallized TiO2 in the form of rutile on its surface. This work contributes to the knowledge about the incorporation of semiconductor nanoparticles into MOFs for photocatalytic applications