Layer-by-layer assembly and photocatalytic activity of titania nanosheets on coal fly ash microspheres

In order to address the problem with titania distribution and recovery, series of Ti_0.91O₂/CFA photocatalysts (Ti _0.91O₂/CFA- n, n = 2,4, 6, and 8) were fabricated by assembling Ti_0.91O₂ nanosheets on coal fly ash (CFA) microspheres via the layer-by-layer assembly (LBLA) process and characterized by scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), N ₂-sorption, and ultraviolet-visible absorption (UV-vis) techniques. The SEM images and UV-vis spectra illustrated that Ti_0.91O ₂ nanosheets were immobilized successfully on the CFA by the LBLA approach and changed the characteristics of CFA noticeably. The photocatalytic activity of Ti_0.91O₂/CFA was evaluated by the photodegradation of methylene blue (MB) under UV irradiation. The results demonstrated that Ti_0.91O₂/CFA-6 showed the best photocatalytic activity among the series of Ti_0.91O₂/CFA irradiated for 60 min, with a decoloration rate above 43%. After photocatalysis, the Ti_0.91O₂/CFA could be easily separated and recycled from aqueous solution and Ti_0.91O₂ nanosheets were still anchored on the CFA.