Photocatalytic oxidation of methylene blue by titanium dioxide in an integrated photoreactor-membrane filtration unit.

摘要

In this Dissertation, the integrated photoreactor-membrane filtration unit was novelized for the degradation of methylene blue (MB). Photocatalytic oxidation took place in an annular flow-through photoreactor whereas the titanium dioxide (TiO{dollar}sb2{dollar}) particles used as catalysts were suspended in the solute. TiO{dollar}sb2{dollar} particles were separated from the slurry by a membrane filtration unit and reused in the photocatalytic process for many cycles. An ultrafiltration hollow fiber membrane, UFP-100-E-3A, was used for this application.; In the first section of the study, the effects of operational parameters and the mode of operations on the photocatalytic oxidation of MB are investigated. The operational parameters, TiO{dollar}sb2{dollar} loading, initial concentration of MB, and pH, were observed in serial experiments. Operation modes such as circulation flow rate and initial solution volume were adjusted during various conditions. The effects of these factors on the degradation of MB are described.; The second section of the study measured the separation efficiency of TiO{dollar}sb2{dollar} particles from the slurry at different operational parameters and operation modes. Parameters included: (1) initial TiO{dollar}sb2{dollar} loading, (2) circulation flow velocity, and (3) transmembrane pressure. The effect of circulation flow rate and of transmembrane pressure on the permeate flux was studied by a series of experiments. The effect of TiO{dollar}sb2{dollar} loading on the permeate flux was also observed. The modeling considerations of these study conditions were described. In addition, the effect of transmembrane pressure and cross-flow velocity on the residual concentration of TiO{dollar}sb2{dollar} in the system was examined.; Finally, an integrated photocatalytic-membrane filtration unit was studied using operation parameters and modes based on findings described in sections one and two. The efficiency of the photocatalytic degradation of MB was determined by measuring MB concentrations and total organic carbon (TOC) of the solution. The efficiency of reusing the TiO{dollar}sb2{dollar} from the membrane separation unit is also described. In addition, the quality of permeate is discussed in terms of turbidity and of the particles in the permeate.