Novel one step fabrication of raspberry-like TiO2@yeast hybrid microspheres via electrostatic-interaction-driven self-assembled heterocoagulation for environmental applications

A simple and economical approach for the fabrication of raspberry-like TiO2@yeast hybrid microspheres via electrostatic-interaction-driven self-assembly heterocoagulation is presented. In this method, the opposite zeta-potentials of titanium dioxide (TiO2) nanoparticles and yeast were achieved by tuning the pH of their aqueous suspensions. TiO2@yeast hybrid particles with raspberry-like morphology were obtained once the two aqueous suspensions were mixed. The interaction between host yeast core and guest TiO2 nanoparticles was investigated by FT-IR spectroscopy. The shapes of the resulting products were identified by field-emission scanning electron microscopy (FESEM). The results show that the TiO2@yeast hybrid microspheres have ordered elliptic shapes of uniform size (length = 2.6 +/- 0.5 mu m; width = 2.0 +/- 0.3 mu m). FT-IR spectra show that the unique surface traits of the primitive yeast and TiO2 nanoparticles are responsible for the homogeneous attachment of guest TiO2 nanoparticles onto the host yeast microspheres. The effectiveness of the raspberry-like TiO2@yeast hybrid microspheres for the removal of water contaminants is shown by application to the decolourization of methylene blue. The removal of the dye is attributed to the combined effect of bio-sorption at the yeast core and photocatalytic degradation driven by the attached TiO2 nanoparticles. (C) 2011 Elsevier B.V. All rights reserved.