| The core-shell structure composite materials show very good application prospect due to the combination of the function of the core and the shell. Especially for the strawberry-like TiO2@yeast photocatalyst, it combines the biological adsorption function of yeast and the ability of photocatalysis from TiO2 particles. Hence, the strawberry-like TiO2@yeast photocatalyst is becoming more and more widely used in the field of photocatalytic for the treatment of wastewater. However, how to control its structure parameters during the synthesis process is becoming a more and more significant topic. Therefore, this research dedicated to the study of its synthetic regulation of strawberry- like TiO2@yeast. Meanwhile, the obtained products were characterized by varies characterization means to study their physical and chemical properties. In the typical treatment of wastewater, the photocatalytic ability of TiO2@yeast was represented by the treatment of lead, mercury, copper and cyanide. Sacrificial agents were employed to explore the improvement of the photocatalytic performance.(1)A novel strawberry- like TiO2@yeast hybrid microsphere was fabricated by simple hydrothermal method using TiOSO4 as raw materials. The synthetic process was controlled by the pH of the synthetic system, and the successful synthesis of TiO2@yeast can be attributed to the opposite charge of yeast and TiO2. The composite catalyst has the elliptic spherical shape of yeast, shows a good dispersion, and has a uniform particle size distribution. The strawberry- like TiO2@yeast was obtained when the pH of the system was 5, and the TiO2@yeast has good response ability for ultraviolet light.(2) Strawberry- like TiO2@yeast hybrid microspheres with controllable structure were fabricated by a simply controllable hydrolysis method using titanium tetrachloride as Ti source. The composite catalyst has the elliptic spherical shape of yeast, shows a good dispersion, and has a uniform particle size distribution. The phy-chemical characters of the two different samples were verified by SEM, XRD, and UV-vis, respectively.(3) The applications of the as-prepared composite microspheres were evaluated by the treatment of lead, mercury and simultaneous removal of a mixture of cyanide and copper metal ions. The synergistic mechanism of the bio-adsorption of yeast and photo-catalysis of nano TiO2 was ascertained. Due to the synergistic mechanism, the treatment effect of TiO2@yeast was much improved compared with the biological adsorption or photocatalytic. In dealing with two different kinds of pollutants at the same time, TiO2@yeast gets a good treatment effect, which can be owed to the combination of bio-adsorption of yeast and photo-catalysis of nano-TiO2. To make research on the catalytic kinetics, the obtained data were employed to fit the first-order kinetics, second-order kinetics and Langmuir-Hinshelwood kinetics. A hypothesis was assumed to explanation the mechanism of the improved photocatalytic ability.(4) With formic acid as a scavenging agent of h+, silver nitrate as a scavenging agent of e-, sodium chloride as a scavenging agent of dissolved oxygen in water, the impact of scavenging agent on the photocatalytic ability was studied. Formic acid as a scavenging agent of h+, restrained greatly the photocatalytic oxidation process of cyanide and at the same time accelerated the photocatalytic reduction process of copper. Silver nitrate as a scavenging agent of e-, due to the competition between silver and copper as well as the passivation theory, restrained greatly the photocatalytic oxidation process of copper and at the same time accelerated the photocatalytic oxida tion process of cyanide. The presence of sodium chloride restrained both the photocatalytic oxidation process of cyanide and the photocatalytic reduction process of copper. The pollutants can be selectively removed by adding different kinds of scavenging agent. The photocatalytic process can be described by fitting the Langmuir-Hinshelwood kinetics.In this paper, the TiO2@yeast can be controllable obtained by changing the reaction condition and the process of experiments were simple, easy to operate, environmental friendly. The photocatalytic ability was greatly improved by the combination of biological adsorption of yeast and the photocatalytic performance of nano-TiO2 particles. In the application of scavenging agent to study on the effect of photocatalytic, the pollutants can be selectively removed by adding different kinds of scavenging agent, and provides a theoretical reference for industry application. |
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