Fabrication Of Yeast-carbon Composite Microspheres And Their Application Performance For The Treatment Of Dye Effluents

The removal of dye wastewater has got increased attention due to their complex chemical structures, deep chromaticity and highly stable, which makes them usually difficult to degrade. However, porous carbon materials has attracted scientists interests due to its large specific surface area, abundant surface functional groups and excellent adsorption property. In this paper, we prepared two composite materials using yeast cells as raw material. So, we provide new materials which are novelty and environmentally friendly for the treatment of dye effluents.（1） Porous hollow microspheres（PHCMs） fabricated from yeast cells by hydrothermal treatment have stimulated much interest because of their outstanding chemical and physical properties including low effective densities and high specific surface areas. Herein, the functionalizations of PHCMs by further attachment of Fe₂O₃ nanoparticles onto the surface were carried out. The structure of resulting Fe₂O₃@PHCMs products were characterized by field emission scanning electron microscopy（FE-SEM）, energy dispersive spectrometry（EDS）, X-ray diffraction（XRD） and Fourier transformed infrared spectroscopy（FT-IR）, respectively. FE-SEM and EDS ascertains that the Fe₂O₃@PHCMs composite microspheres had ordered oval shapes of uniform size with the length of 2.0±0.2 μm and width of 1.8±0.2 μm. XRD pattern indicates that the main crystal structure of attached Fe₂O₃ nanopatticles is hexagonal hematite crystal and the hollow microspheres belongs to amorphous phase. Fourier transform infrared spectroscopy（FT-IR） elucidates that the functional groups or chemical bonds inherited from the PHCMs were critical to the for mation of the composites.（2） The absorptive applications of the as- fabricated Fe₂O3@PHCMs were assessed using methyl violet（MV） as an adsorbate by a batch adsorption experiments. The Fe₂O₃@PHCMs hybrid microspheres were successfully synthesized via hydrothermal method and calcinations route. The results of batch adsorption experiments show that the uptake efficiency was highly dependent on the pH, initial dye concentration, adsorbent dosage and temperature. It was found that the equilibrium data fitted well to the Langmuir isotherm model, implying that the homogeneous monolayer adsorption takes place on the surface of adsorbent. K inetics of the adsorption process was best represented by the model of pseudo-second-order kinetics. The intraparticle diffusion model showed two steps where intraparticle diffusion was not the only rate controlling step of the adsorption process. Thermodynamic studies manifested that the adsorption was a spontaneous, endothermic process. Further, the dye- loaded Fe2O3@PHCMs could be effectively regenerated by hydrogen peroxide which affirmed that the as-prepared adsorbent has excellent regenerative ability.（3） TiO₂@yeast-carbon hybrid composites have successfully obtained via a facile electrostatic self-assembly method using yeast-carbon as carriers. The products are characterized by field emission scanning electron microscopy（FE-SEM）, energy dispersive spectrometry（EDS）, X-ray diffraction（XRD） and Fourier transformed infrared spectroscopy（FT-IR）, respectively. The results show that the hybrid TiO₂@yeast-carbon microspheres have ordered elliptic shapes of uniform size with length of 3.6±0.3 μm and width 2.5±0.5 μm. XRD pattern indicates that the main crystal structures of TiO₂@yeast-carbon microspheres are consisted of anatase and rutile. The catalytic performance was investigated by analyzing the influence of factors such as the initial p H, ion species and catalyst dose. The highest percentage removal of Cresol Red dye（CR） was achieved at catalyst dose of 5 g/L and pH of 5. The co-existing ion of NO3-, H2PO4-, Cu2+ was found to inhibit the activity of photocatalysis, and the co-existing ion Mg2+ had no significant effect on photocatalysis reaction.