Abstract
Nowadays, there is a growing concern about the environmental impacts of colored wastewater. Thus, the present work aims the synthesis, characterization and determination of photocatalytic activity of iron oxide (Fe2O3) nanocatalyst, evaluating the effect of hybridization with titanium (TiNPs-Fe2O3) and silver (AgNPs-Fe2O3) nanoparticles, on the degradation of Rhodamine B dye (RhB). Nanocatalysts were characterized by XRD, SEM, TEM, FTIR, N2 porosimetry (BET/BJH method), zeta potential and DRS. Photocatalytic tests were performed in a slurry reactor, with the nanocatalyst in suspension, using RhB as a target molecule, under ultraviolet (UV) and visible radiation. Therefore, the photocatalytic activity of the nanocatalysts (non-doped and hybridized) was evaluated in these ideal conditions, where the AgNPs-Fe2O3 sample showed the best photocatalytic activity with a degradation of 94.1% (k = 0.0222 min−1, under UV) and 58.36% (k = 0.007 min−1, under visible), while under the same conditions, the TiO2-P25 commercial catalyst showed a degradation of 61.5% (k = 0.0078 min−1) and 44.5% (k = 0.0044 min−1), respectively. According with the ideal conditions determined, reusability of the AgNPs-Fe2O3 nanocatalyst was measured, showing a short reduction (about 8%) of its photocatalytic activity after 5 cycles. Thus, the Fe2O3 nanocatalyst can be considered a promising catalyst in the heterogeneous photocatalysis for application in the degradation of organic dyes in aqueous solution.
Highlights
Nowadays, there is a growing concern about the environmental impacts of colored wastewater
Nanocatalyst has emerged as an alternative to increase catalytic efficiency, since it has advantages over commercial catalysts, such as higher specific surface area and porosity, making them with great potential application in heterogeneous photocatalysis[10]
One of the strategies used to increase the photocatalytic activity of nanocatalysts is the usage of hybridization with noble metal and metals, in order to reduce the recombination between photoelectrons/holes pairs and reducing the energy required to its photoactivation, allowing its application to visible radiation[11,12,13,14,15,16]
Summary
There is a growing concern about the environmental impacts of colored wastewater. It is estimated that there are more than 100,000 synthetic dyes, with an annual production of more than 700,000 tons worldwide, generating a significant amount of wastewater[1] These colored waters are characterized by complex aromatic compounds, making their biodegradation difficult, becoming an environmental liability. Among the most used catalysts are titanium dioxide (TiO2), cadmium sulfide (CdS), zinc oxide (ZnO), zinc sulphide (ZnS), tungsten trioxide (WO3), tin dioxide (SnO2) and iron oxide III (Fe2O3)[6] These catalysts www.nature.com/scientificreports generally present a low specific surface area and porosity, limiting intraparticle diffusion of organic pollutants, compromising its photocatalytic activity[7,8,9]. It presents the chromophoric groups (−C=C −/− C=N−), as well as a characteristic carcinogenicity and neurotoxicity activity
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