One-pot synthesis of porous TiO2/BiOI adsorbent with high removal efficiency and excellent recyclability towards tetracyclines

Considerable efforts have focused on pursuing the efficient removal of antibiotic contaminants by combining adsorbents with photocatalysts. However, the reported adsorbents/photocatalysts still suffer from critical drawbacks including low adsorption rate, low mineralization rate, and complicated preparation procedures, greatly restricting their practical application. In this work, we report a facile method to develop porous TiO2/BiOI adsorbent through a one-pot hydrothermal process and subsequently low-temperature calcination (280 °C). Adsorption experiment shows that porous TiO2/BiOI realizes almost complete removal (99.4%) of tetracyclines, far beyond the values of BiOI (20.2%) and TiO2 (71.1%). Notably, one-pot synthesis promotes the mass production of TiO2/BiOI without obvious loss in adsorption capacity. More importantly, TiO2/BiOI adsorbent can be simply regenerated by complete photodegradation of the adsorbed tetracyclines on TiO2/BiOI, and regains above 98% of its adsorption capacity for 10 cycles, successfully overcoming the limitations of environment-unfriendly regeneration conditions, low adsorption capacity, and poor recyclability for most of the reported adsorbents/photocatalysts. Additionally, adsorption mechanism is deduced to be mainly electrostatic attraction, hydrogen bonding, and pore filling according to adsorption performance. Therefore, the design concept we present here provides a new perspective for the development of reactive adsorbents with excellent removal efficiency and recyclability through a facile one-pot synthesis.