Removal of estradiol from water with a hybrid MIP-TiO2 catalytic adsorbent.

Abstract

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 m2 g−1 . Adsorp tion 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.