Catalisadores verdes de ferro preparados em presença de glicerol e aplicados na degradação do azocorante Alaranjado de metila pelo Sistema Fenton Heterogêneo

• Autor(a) principal: Trotte, Natália da Silva Freitas
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/15627
• topic: Water; Dye; Heterogeneous Fenton; Glycerol; Iron catalysts; Palladium; Água; Corante; Fenton Heterogêneo; Glicerol; Catalisadores de ferro; Paládio; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA INORGANICA

It is not new that water is essential for the existence of life on Earth. However, as much as its importance it is well known of, people pollute the rivers and their springs, forgetting how great is its value not only for our permanence on Earth, but also for our future generations. The anthropogenic activities have dramatically diminished the quality of this good. Among these, the industrial activity stands out, because the dyes consist in an important waste released by the textile industries. When these persistent compounds are not well adhered to the fiber, they are often discarded in the water bodies. Thus, a large amount of studies has been done in order to find ways to degrade dyes, advanced oxidative processes are an example of this. Through the Fenton System, iron catalysts have been performing excellent catalytic activity towards a wide variety of pollutants, besides of being abundant and low cost. Recently, we have sought to use of environmentally friendly compounds instead of traditional toxic reducing agents to prepare the so-called green iron catalysts. This work describes the preparation of metallic catalysts, in the presence of glycerol as a reducing agent and environmentally friendly stabilizer, for application in the degradation of the azo dye methyl orange by the heterogeneous Fenton system. First, iron catalysts in the presence of zinc(II) and nickel(II) metal ions were prepared using silica as support. Next, palladium nanoparticles were prepared in the presence of glycerol and supported in magnetite at different loadings. The catalysts were characterized by XRD (X-ray diffraction), AAS (Atomic Absorption Spectroscopy), SEM (Scanning Electron Microscopy), Mössbauer Spectroscopy, Infrared spectroscopy and Thermogravimetry, which revealed the formation of oxalates of zinc(II), nickel(II) and iron(II)/(III) as a result of the oxidation of glycerol by the nitrate present in the metal precursors. Superparamagnetic nanoparticles of iron(III) oxyhydroxide were also formed. The catalysts were applied to the heterogeneous Fenton degradation of the azo dye Methyl Orange. The reaction parameters were optimized as catalyst dosage, hydrogen peroxide concentration, pH and reaction temperature. Complete dye degradation was observed after 180 minutes of reaction. Thermogravimetric analyses revealed that with the addition of Pd to the magnetite, the catalysts became more stable. The degradation of the azo dye was carried out both by adsorption and chemical oxidation, varying some parameters such as: temperature and mass of the catalyst. There was a high degradation percentage of the dye around 240 min of reaction.