Avaliação de eficiência de fotocatalisadores à base de dióxido de titânio na degradação de formaldeído

Abstract

Formaldehyde, widely used in industries and consumer products, is a highly toxic and potentially carcinogenic substance associated with respiratory irritation, dermatitis, and environmental risks due to its persistence in aquatic ecosystems. Among Advanced Oxidation Processes (AOPs), photocatalysis, which uses light-activated photocatalysts, enables the degradation of persistent pollutants. A highly promising photocatalyst is titanium dioxide (TiO₂). Two TiO₂ samples were compared—one thermally treated in a muffle furnace (GM) and the other by a hydrothermal method (HT)—both synthesized via the sol-gel method. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy, and specific surface area analysis (BET). The results showed that the hydrothermal treatment yielded a photocatalyst with a smaller crystallite size (51 Å) and a larger surface area (246.8 m²/g) compared to the muffle furnace treatment, which had a crystallite size of 179 Å and a surface area of 51.8 m²/g. Photocatalytic experiments demonstrated that the HT photocatalyst was more efficient, degrading 93% of formaldehyde in 120 minutes, while GM achieved 89% degradation in the same experimental time. The higher efficiency of the HT photocatalyst is attributed to its larger surface area, which favors the generation of free radicals. The hydrothermal treatment is more advantageous in terms of both efficiency and energy cost.