Banca de QUALIFICAÇÃO: NAYANE OLIVEIRA CHAVES
12/03/2024 10:28
Blast furnace dust waste (BFDW) proved efficient as a photocatalyst for the decolorizationof methylene blue (MB) dye in water. Structural analysis unequivocally identified α-Fe2O3 as thepredominant phase, constituting approximately 92%, with a porous surface showcasing unique10–30 nm agglomerated nanoparticles. Chemical and thermal analyses indicated surface-bound waterand carbonate molecules, with the main phase’s thermal stability up to 900 ◦C. Electrical conductivityanalysis revealed charge transfer resistance values of 616.4 Ω and electrode resistance of 47.8 Ω. TheMott-Schottky analysis identified α-Fe2O3 as an n-type semiconductor with a flat band potentialof 0.181 V vs. Ag/AgCl and a donor density of 1.45 × 1015 cm−3. The 2.2 eV optical bandgapand luminescence stem from α-Fe2O3 and weak ferromagnetism arises from structural defects andsurface effects. With a 74% photocatalytic efficiency, stable through three photodegradation cycles,BFDW outperforms comparable waste materials in MB degradation mediated by visible light. Theelemental trapping experiment exposed hydroxyl radicals (•OH) and superoxide anions (•O−2) as theprimary species in the photodegradation process. Consequently, iron oxide-based BFDW emerges asan environmentally friendly alternative for wastewater treatment, underscoring the pivotal role of itsunique physical properties in the photocatalytic process.
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