Photocatalytic Nanocomposite Microsponges Of Polylactide-Titania For Chemical Remediation In Water

We developed a simple and environmentally friendly approach for synthesis of photocatalytic nanocomposites composed of porous polylactic acid microparticles (PLA) with incorporated anatase titania nanoparticles (TiO2) for sorption and UV-triggered degradation of organic compounds. Titania is integrated with PLA via 'mixed' and 'grown' methods by mixin anatase and PLA via oil/water emulsion or by growing TiO2 in a PLA matrix from a titanium precursor under mild reaction conditions. The resulting mixed and grown PLA/TiO2 microparticles were prepared in the absence or presence of the porogen 2-methylpentane (2MP) and have an average size from 30 to 100 mu m. The 'grown titania' is produced amorphous-crystalline mixture with similar to 9% mixed anatase-rutile phase and an average nanoparticale size of similar to 5 nm. We have demonstrated that the sorption capacity, dye degradability, and composite disintegration can be controlled by varying the microparticle porosity and distribution of incorporated titania nanoparticles. Both types of PLA/TiO2 composites removed rhodamine 6G from water (up to 60% of the initial amount in six hours of UV exposure time) unlike negligible dye removal observed for titania-free PLA particles. We also found that 'grown' microparticles made with and without 2MP were about 20-30% more efficient in dye removal compared to the corresponding mixed systems. Finally, the presence of titania nanoparticles significantly increased the degradation of PLA. Both 'mixed' and 'grown' microparticles containing 20% TiO2 exhibited 54 +/- 1 and 52 +/- 1% weight loss, respectively over 21 days of UV treatment. Owing to their biodegradability and high removal efficiency, these composite microsponges can be applied as nontoxic photocatalytic materials for environmental cleanup of contaminated water. In addition, the synthetic approaches introduced herein offer a simple, scalable, and environmentally friendly method, which might be potentially applied in commercial manufacturing.