The fabrication of TiO2 supported on slag-made calcium silicate as low-cost photocatalyst with high adsorption ability for the degradation of dye pollutants in water

Abstract

In this work, a composite photocatalyst of TiO2 supported on the slag-made calcium silicate (TiO2/SCS) was synthesized by employing a facile mixing process and using blast furnace slag as a low-cost and abundant precursor of SCS. The characterization results revealed that the open framework structure of SCS was covered by well-dispersed TiO2 nanoparticle aggregates, indicating the close combination of titania and calcium silicate in the TiO2/SCS photocatalyst. Higher specific surface areas could be obtained for TiO2/PCS (PCS: pure calcium silicate) and TiO2/SCS composites, indicating their better adsorption capabilities than that of bare TiO2. The degradation of methylene blue (MB) by TiO2, TiO2/PCS and TiO2/SCS composites with different weight percentages of titania was carried out under UV-light irradiation to systematically investigate their photocatalytic activities, and the TiO2 content of 60wt% (TiO2-60/SCS) was found to be the best one to achieve the maximum rate of MB degradation, which may be due to the high specific surface area and good adsorption capacity of the composite photocatalysts. The degradation of methyl violet (MV) and methyl orange (MO) dyes indicated that the obtained photocatalysts can effectively adsorb cationic molecules (MB and MV) but have little absorption toward negatively charged molecules (MO), which play a key role in the subsequent photocatalytic degradation of dye pollutants.