Removal of Estradiol from Water with a Hybrid MIP-TiO2 Catalytic Adsorbent
2020
Tonucci, Marina Caldeira | dos Santos Xavier, Leandro Pablo | da Silva, Adilson Candido | Aquino, Sergio F. | Baeta, Bruno Eduardo Lobo
17β-Estradiol (E2) is one of the main compounds responsible for estrogenic activities in sewage and natural waters and has been found in these matrices all around the world, thereby justifying the development of technologies for its removal. In this work, pure or TiO₂-containing molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were prepared using E2 as template. The materials were characterized by infrared spectroscopy, X-ray diffraction, adsorption/desorption of N₂, and scanning electron microscopy (SEM). The characterization analyses showed that TiO₂ was incorporated in the polymers and that all materials could be characterized as mesoporous and had surface areas ranging from 238 to 279 m²g⁻¹. Adsorption studies showed MIP-TiO₂ had a high capacity to adsorb E2 from the water phase leading to qₘₐₓ values of 15.16 to 26.49 mg g⁻¹ at temperatures from 25 to 45 °C, respectively. In addition, the thermodynamic study showed that the adsorption process is endothermic, spontaneous, and entropically driven. The results also showed that the presence of TiO₂ decreases the adsorption performance of MIP-TiO₂ when compared with MIP (without the photocatalyst) during the adsorption. However, the application of MIP-TiO₂ in a process of adsorption followed by photocatalysis resulted in 100% of E2 removal allowing the reuse of adsorbent. In addition, MIP-TiO₂ maintained its E2 removal capacity even after five cycles of regeneration–reuse, which shows the ability of UV light to regenerate the specific adsorption sites. The results presented in this paper show MIP-TiO₂ has potential to be applied in water treatment systems to remove E2.
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