Fabrication and photocatalytic activity of TiO2 composite membranes via simultaneous electrospinning and electrospraying process

In present study, a simultaneous electrospinning and electrospraying(SEE) process was employed to produce microclusters of TiO_2 nanoparticles and interlock them in nanofibrous network. The photocatalytic composite membranes(PCMs) were fabricated by electrospraying TiO_2 nanoparticle suspension into microcluster form that dispersed and entrapped within nylon-6 electrospun fiber membrane. Three PCMs membrane with TiO_2 content of 52.0, 83.6,and 91.7 wt.% were successfully fabricated. The membrane consisted of TiO_2 microclusters,ranging in sizes from around 0.3 to 10 μm, distributed uniformly within the nylon-6 nanofibrous network. PCMs photocatalytic activity against Methylene Blue(MB) in aqueous solution showed more than 98% MB removal efficiency after 120 min of photocatalytic oxidation(PCO) for all PCMs. For PCM with the highest TiO_2 content tested for 5 PCO cycles, it was found that most of their TiO_2 content remained incorporated within the nanofibrous structure. The concept of nanoparticles clusters entrapment with SEE fabrication employed here provide a simple and effective method for reducing detachment of nanostructure phase from nanocomposite membrane.     

Mathematical model for photocatalytic destruction of organic contaminants in air

Photocatalytic oxidation (PCO) was investigated in a bench-scale reactor for the abatement of two airborne organic contaminants: toluene and ethanol. A mathematical model that includes the impacts of light intensity, initial contaminant concentration, catalyst thickness, and relative humidity (RH) on the degradation of organic contaminants in a photocatalytic reactor was developed to describe this process. The commercially available catalyst Degussa-PtTiO2 was selected to compare with the MTU-PtTiO2-350 catalyst, which was synthesized by the sol-gel process, platinized, and calcined at 350 degrees C. For toluene removal using the MTU-PtTiO2-350 catalyst, the degradation rate increased with increases in light intensity from 0.2 to 2.2 mW/cm2 and in catalyst thickness from 0.00037 to 0.00361 cm. However, further increases in light intensity and catalyst thickness had only slight effect on the toluene degradation rate. Increasing the initial concentration from 6.29 to 127.9 microg/L and the RH from 10 to 85% resulted in decreases in the toluene degradation rate. For ethanol removal using the MTU-PtTiO2-350 catalyst, the degradation rate increased more rapidly with an increase in RH from 17 to 56%; the RH had little effect on the ethanol degradation rate while it further increased from 56% to 82%. We discuss applicability of the model to estimate the influence of process variables and to evaluate photocatalyst performance.