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

In this work, the formation of SiO2 coated TiO2 (SiO2-TiO2) 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 SiO2-TiO2 composite formation, respectively. For this purpose, the HCl solution was used as leaching agent in the hydrothermal treatment of TBBFS at 180 degrees C, which led to Si and Ti leaching for the formations of anatase TiO2 phase and amorphous SiO2 phase. In comparison, the leaching process in HF led to the formation of metal fluorides and TiO2 with the dissolution of most Si. Accordingly, different amount of HF addition in HCl leaching of TBBFS led to the SiO2/TiO2 mass ratio in composite varying from 1.1 to 3.7. Moreover, the various mass ratio of SiO2 to TiO2 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 SiO2/TiO2 mass ratio. The adsorption of positive dye on negative SiO2 and the simultaneous photodegradation on available TiO2 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.