Síntese de compósitos baseados em óxido de ferro, dióxido de titânio e material carbonáceo pelo método da combustão para aplicação em fotocatálise heterogênea

Abstract

Environmental contamination is a growing global concern, driving the development of alternative mitigation strategies. Heterogeneous photocatalysis is a promising approach, yet conventional semiconductors such as titanium dioxide and iron oxide face limitations, including the need for artificial UV radiation and rapid electron-hole recombination. This work explores the synthesis and application of novel composites based on titanium dioxide, iron oxide, and carbonaceous material derived from mango residue, using solution combustion synthesis with urea as fuel. Seven samples were produced with varying reagent ratios, resulting in distinct thermal profiles (TG/DTG/DTA), crystalline phases (hematite, maghemite, magnetite; XRD, FTIR), increased specific surface area in carbon-containing samples, diverse morphologies (SEM/EDS), and altered optical properties (UV–Vis spectroscopy, band gap), confirming the formation of new compounds with unique characteristics. Photocatalytic tests under UV irradiation (125 W) demonstrated that the FeTi-1-1 sample achieved the highest degradation efficiency for both pharmaceuticals and dyes. However, when dyes were mixed or solar illumination was applied, FeTi-1-2 and FeTiC-2-1-1 samples performed better. Exposure to natural light for 30 minutes led to selective inhibition of E. coli (Gram-negative) bacteria. The addition of mango residue enhanced the magnetic response, facilitating separation and reuse of the catalysts. Overall, incorporating the residue improved solar light absorption and photocatalytic efficiency under solar irradiation.