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 TiO2 nanoparticles and interlock them in nanofibrous network. The photocatalytic composite membranes（PCMs） were fabricated by electrospraying TiO2 nanoparticle suspension into microcluster form that dispersed and entrapped within nylon-6 electrospun fiber membrane. Three PCMs membrane with TiO2 content of 52.0, 83.6,and 91.7 wt.% were successfully fabricated. The membrane consisted of TiO2 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 TiO2 content tested for 5 PCO cycles, it was found that most of their TiO2 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.

Surface modification of polypropylene non-woven fibers with TiO_2 nanoparticles via layer-by-layer self assembly method:Preparation and photocatalytic activity

Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic acid）（PSS） and poly（diallyl-dimethylammonium chloride）（PDADMAC） to improve the anchoring of the Ti O2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic Ti O2 nanoparticles to construct Ti O2/PDADMAC bilayer in the Lb L fashion. The number of deposited Ti O2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust Ti O2 loading. The Lb L technique showed higher Ti O2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue（MB）. Results showed that the Ti O2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of Ti O2 powder dispersed in solution. The deposition of Ti O23 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr.Ti O2-Lb L constructions also preserved Ti O2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of Ti O2 particles from the substrate outer surface. However, even in the third cycle, the Ti O2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.