Adsorption and Photocatalytic Degradation of Reactive Brilliant Red K-2BP by TiO2/AC in Bubbling Fluidized Bed Photocatalytic Reactor

An activated carbon-supported titanium dioxide photocatalyst (TiO2/AC) was prepared by a spinning coating method and applied in a designed bubbling fluidized bed photocatalytic reactor (BFBPR). Adsorption and photocatalytic degradation of reactive brilliant red K-2BP in BFBPR were investigated considering the pH value, Na2SO4 added, and initial dye concentration. The experimental results indicated that the adsorption and photocatalytic degradation efficiencies of K-2BP were influenced by the pH value, Na2SO4 added, and initial dye concentration. The adsorption and photocatalytic degradation of K-2BP was approximated to the maximum value at pH value 5.7. The complex influence of Na2SO4 added on photocatalytic degradation of K-2BP at alkaline suspension was observed and explained according to the adsorption models proposed and degradation mechanism of a new free radical (SO4 •−) produced. In addition, the presence of Na2SO4 plays dual functions, i.e., salt bridge-role in adsorption for Na+ and competition adsorption between anion dye molecules and SO4 2−, conformed by adsorption models proposed and FT-IR spectra for dye adsorption on TiO2/AC. The mass-transfer limited and screening effect that resulted from variation of the initial dye concentration may be approximated to the minimum effect at concentration of 3.75 mg L−1, with the maximum degradation efficiency above 80%. The Langmuir−Hinshelwood kinetic model was applied to explore the adsorption and degradation. Finally, the special reaction paths were inferred with variation of experimental environments.