Preparation Of Yeast-based Composite Microspheres And Their Performance For Treatment Of Wastewater

The technical feasibility of various low-cost sorbents for heavy metal and organic dyes removal from wastewater has been reviewed. The use of low-cost sorbents has been investigated as replacements of current costly methods for removing heavy metals and organic dyes from contaminated water. So far, adsorption and catalysis have been became the main techniques for the treatment of heavy metal and dye containing effluents. However, using the sole method is generally costly, less efficient, and cause seriously secondary pollution to environment in practical application. Therefore, in this paper, it devoted to fabricate a series of new materials which are economic, efficient and environmentally friendly for the treatment of effluents. Meanwhile, the obtained products were characterized by varies characterization means to know more about their physical and chemical properties.(1)TiO2@yeast hybrid materials with controllable structures were successfully synthesized via a facile hydrothermal method. The as-prepared TiO2@yeast microspheres were thoroughly characterized by various techniques. FE-SEM and EDS revealed that the TiO2@yeast hybrid microspheres have rough surface morphology and uniform diameter with good dispersity, and the core-shell or raspberry-like structure can be readily controlled by adjusting the amount of titanium tetrabutoxide(TBOB). XRD pattern indicated that the anatase phase of TiO2 nanoparticles with amorphous yeast. FT-IR demonstrated that the formation of controllable TiO2@yeast composite microspheres was related to surface chemical functional groups of yeast. The settleability test displayed that the hybrid microspheres had an excellent settling performance. In contrast with TiO2 nano-particles, the photocatalytic performance of TiO2@yeast composite microspheres have an excellent performance for the reduction of Cr(VI) under UV light irradiation.(2) Fe3O4@yeast composite microspheres, whose properties integrate the biosorption features of yeast cells with the excellent magnetic and catalytic properties of Fe3O4 nanoparticles were synthesized by a simple electrostatic-interaction-driven self-assembly heterocoagulation. They were successfully applied in an up-flow packed column for the removal of the model water contaminant methylene blue dye(MB) by consecutive bioadsorption-heterogeneous Fenton oxidation cycles. The as-synthesized Fe3O4@yeast composites were characterized by field emission scanning electron microscopy(FE-SEM), energy-dispersive spectroscopy(EDS), powder X-ray diffraction(XRD) and Fourier transform infrared(FT-IR) spectroscopy. The experimental breakthrough curves measured at different influent MB concentration, flow rate, bed height and pH were modeled by the Thomas and Yoon-Nelson model. In addition, the BBD type of response surface method was used to model the adsorption methylene blue through Fe3O4@yeast composites. It has been verified that the BBD type of response surface method can accurately describe the process of adsorption. Thereinto, the concentration of methylene blue, flow rate, p H, the interaction of concentration and pH, the interaction of flow rate and pH, the square of pH effect is remarkable.The in-situ regeneration of the contaminant-loaded Fe3O4@yeast microspheres and their reuse in multiple cycles was demonstrated by triggering the heterogeneous Fenton-like reaction catalyzed by the supported magnetite. The raspberry-like Fe3O4@yeast magnetic microsphere should be a promising and practical adsorbent for removal and destruction of positively charged organic compounds in wastewater.In this article, two kinds of new composite microspheres were fabricated which have integrated the biosorption features of yeast cells with the excellent catalytic properties of nanoparticles effectively. And the synthesis techniques have many obvious advantages such as environmental friendly, easy operation, mild reaction and cost inexpensive. The obtained products have the high efficiency for treating wasterwater and no secondary pollution which could be effectively to treat the waste water and could realize the goal of improving environment and utilizing resources.