Photocatalytic performance of SiO2-TiO2 composite via F-assisted restructure of Ti-bearing slag

In this work, the formation of SiO 2 coated TiO 2 (SiO 2 -TiO 2 ) composite from titanium bearing blast furnace slag (TBBFS) was carried out by hydrothermal treatment in the acidic solution with the assistance of F -. The basanite and perovskite were two main compositions in TBBFS which provided Si and Ti for the SiO 2 -TiO 2 composite formation, respectively. For this purpose, the HCl solution was used as leaching agent in the hydrothermal treatment of TBBFS at 180C, which led to Si and Ti leaching for the formations of anatase TiO 2 phase and amorphous SiO 2 phase. In comparison, the leaching process in HF led to the formation of metal fluorides and TiO 2 with the dissolution of most Si. Accordingly, different amount of HF addition in HCl leaching of TBBFS led to the SiO 2 /TiO 2 mass ratio in composite varying from 1.1 to 3.7. Moreover, the various mass ratio of SiO 2 to TiO 2 in the composite resulted in the different photodegradation performance of Rhodamine B, where 95% of Rhodamine B was removed on the composite at 1.1-1.2 of SiO 2 /TiO 2 mass ratio. The adsorption of positive dye on negative SiO 2 and the simultaneous photodegradation on available TiO 2 surface were responsible for the effective Rhodamine B removal. Therefore, our result provided a facile approach to the preparation of photocatalyst candidate from TBBFS for the degradation of organic contaminate in the solution.