Continuous removal of trace bisphenol A from water by high efficacy TiO2 nanotube pillared graphene-based macrostructures in a photocatalytically fluidized bed

The continuous removal of trace amounts of BPA from water is presently a challenging issue because of the low degradation constants at these low levels. In this study, TiO2 nanotubes (TNTs) pillared graphene-based macrostructures (TPGBM) were prepared by using TNTs as physical pillars. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analyses, and UV-vis-diffuse reflection spectrum (UV-vis-DRS) and photoluminescence spectrum (PL) data were used to characterize the TPGBM. A high BPA adsorption capacity was obtained by the TPGBM due to the higher specific surface area, more accessible pi-pi adsorption sites and more hydrogen bonding than that of GBM. The BPA occupied adsorption sites in TPGBM may be regenerated by photo-generated electrons induced O-center dot(2)- and (OH)-O-center dot. Both batch experiments and fluidized bed experiments indicated that the TPGBM had good adsorption-photocatalysis synergistic effects toward the decontamination of BPA. The TPGBM showed an outstanding removal performance toward trace BPA in aqueous solution, removing 86% of the BPA at an initial concentration of 0.05 mg/L in the continuous flow system under Xe lamp irradiation. Knowledge from this study provides important technical support and a theoretical basis for the continuous removal of trace environmental endocrine disruptors in water through the use of graphene-based composites.