Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

Abstract

Pure TiO2 and Fe- and Co-doped TiO2 nanoparticles (NPs) as photocatalysts were synthesized using wet chemical methods (sol-gel + precipitation). Their crystalline structure and optical properties were analyzed using X-ray diffraction (XRD), Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible light (UV-Vis) diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of the synthesized nanoparticles was evaluated through degradation of carbamazepine (CBZ) under UV-A and visible-light irradiations. The XRD and Raman analyses revealed that all synthesized nanomaterials showed only the anatase phase. The DRS results showed that the absorption edge was blue-shifted for Fe-doped TiO2 NPs. The decrease in charge recombination was evidenced from the PL investigation for both Co-doped and Fe-doped TiO2 nanomaterials. An enhancement in photocatalytic degradation of carbamazepine in aqueous suspension under both UV-A light and visible-light irradiations was observed for Fe-doped Titania NPs by comparison with pure TiO2. These results suggest that the doping cations could suppress the electron/hole recombination. Therefore, the photocatalytic activity of TiO2-based nanomaterials was enhanced.

Life Cycle Assessment of the Sustainability of Enhancing the Photodegradation Activity of TiO2 with Metal-Doping

“…Quite encouragingly, Fe-TiO 2 presented better results for the removal of CBZ than undoped TiO 2 under both UV-A (96.9% versus 70.1%) and visible light (12.5% versus 7.9%) irradiation [16]. Moreover, while Co-TiO 2 presented worse results than undoped TiO 2 under UV-A irradiation (34.2% versus 70.1%), it also presented better results under visible light irradiation (10.8% versus 7.9%) [16].…”

“…The environmental impacts were compared initially using a weight-based functional unit of 1 kg of nanoparticles, given that this can be used to compare the production of an equivalent amount of nanomaterial. These impacts were subsequently normalized by the photo-degradation efficiency (in %) of the photocatalysts toward the removal of either MO and CBZ under UV-A and visible light-based irradiation, as determined previously by us [15,16]. Such an approach is needed because a weight-based function might not account for the possibility that a more resource-intensive synthesis may be justified later in the use stage (given the improved functionality).…”

“…Our group has been active in this field and has developed several TiO 2 nanomaterials monodoped with different metal ions, e.g., iron (Fe), cobalt (Co), manganese (Mn) and nickel (Ni) [15,16]. The photocatalytic properties of these nanoparticles were evaluated for the photo-degradation of Methyl Orange (MO) [15] and Carbamazepine (CBZ) [16] and compared with the activity shown by undoped TiO 2 . More specifically, undoped TiO 2 and monodoped Co-TiO 2 , Mn-TiO 2 , and Ni-TiO 2 were employed in the photo-degradation of MO under UV-A and visible light irradiation [15].…”

“…We also tested undoped TiO 2 and monodoped Fe-TiO 2 and Co-TiO 2 in the UV-A and visible light-based photodegradation of CBZ [16], a persistent organic pollutant that poses a threat to water quality [14,17]. Quite encouragingly, Fe-TiO 2 presented better results for the removal of CBZ than undoped TiO 2 under both UV-A (96.9% versus 70.1%) and visible light (12.5% versus 7.9%) irradiation [16]. Moreover, while Co-TiO 2 presented worse results than undoped TiO 2 under UV-A irradiation (34.2% versus 70.1%), it also presented better results under visible light irradiation (10.8% versus 7.9%) [16].…”

“…Herein, the aim of this work is to determine the sustainability of monodoping TiO 2 with different transition metal ions (Fe, Mn, Co, and Ni) while considering performance in the UV-A and visible light-based photo-degradation of MO and CBZ [15,16]. The sustainability and associated environmental impacts of each process were analyzed with a life cycle assessment (LCA) study of each synthesis.…”