The Preparation Of Composite Nano-structured Materials And The Research Of Their Photocatalytic And Adsorption Characteristics

Photocatalytic degradation and adsorption are effective methods to remove organicpollutants existed in environment. High efficiency of photocatalyst and adsorbent is animportant index of the high removal of organic pollutants existed in environment. In thepresent, water treatment technology is increasingly improved. With the development ofmaterial science, various kinds of new functional material also emerge continuously. So thecombined application of new material and water treatment technology is a hot research areain nowadays. In this thesis, we synthesis four composite nano-structured materials,including core-shell TiO₂@porous SiO₂ nanoparticles, carbon coated Fe₃O₄ nanoparticles,TiO₂-mounted activated carbon and activated carbon. The performances and theories of theprocess of remove organic pollutants were discussed. The experiment results showed thatthe four prepared materials could remove organic pollutants in water with low cost and highefficiency.1. Preparation of core-shell structured TiO₂@porous SiO₂ nanoparticles and theirapplication to photocatalytic degradation of Bisphenol A in aqueous mediaNovel core-shell TiO₂@porous SiO₂ nanoparticles were prepared via sol-gel andsurface-protected etching processes, and applied to the photocatalytic degradation ofBisphenol A （BPA） under UV irradiation. The porous SiO₂ framework acted as physicalbarrier, effectively stabilizing TiO₂ nanoparticles and keeping its catalysis activity.Furthermore, the thickness of the porous SiO₂ shell can be controlled, and BJH adsorptionaverage pore diameter of the pores on the shell is about 15nm, which allows moleculartransit freely, guarantees higher catalytic efficiency. So the prepared TiO₂@porous SiO₂nanoparticles offere higher degradation efficiency and stability compared with commercialP25 TiO₂ for photocatalytic decomposition of BPA in water. We also discussed theinfluences of photocatalysts dosage and the initial concentration of BPA on removal efficiency. Particular attention was paid to identiy the intermediates and analysis thephotocatalytic degradation mechanism of BPA. Eight conceivable intermediates wereformed during photocatalytic degradation, and their evolution was discussed.2. Preparation of carbon coated Fe₃O₄nanoparticles and their application to removalof Rhodamine B in aqueous mediaThe carbon coated Fe₃O₄nanoparticles （Fe₃O₄/C） were prepared by solvothermal andhydrothermal method, and successfully applied to remove Rhodamine B （RhB） in aqueousmedia. The magnetic nanoparticles were well characterized by scanning electronmicroscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. Adsorption kinetics,adsorption isotherm as well as the effects of adsorbent dosage on removal efficiency wereinvestigated. The adsorption of Fe₃O₄/C to RhB reached equilibrium in 3 h with a maximumadsorption amount of 13.23 mg/g. Langmuir and Freundlich adsorption models wereadopted to explicate the adsorption properties of RhB and Fe₃O₄/C. Adsorption kineticfollowed pseudo-second-order reaction kinetic expression. It was shown that Fe₃O₄/Cnanoparticles possessed excellent magnetic properties and adsorption capacity, and removedRhB rapidly and effectively with the removal efficiency over 90%. Additionally, Fe₃O₄/Cnanoparticles proved re-utilizing, low cost and environmentally friendly.3. Preparation of activated carbon made from waste paper and its application toremoval of Dicamba and Alphanaphthol in aqueous mediaIn this section, activated carbon was prepared from waste paper in laboratory ofourselves，, the waste paper undergone immersed, filtrated, H3PO₄activated and microwaveirradiation. Then activated carbon was well characterized by scanning electron microscopy（SEM）, the result showed the shape of activated carbon was irregular, but the surface ofactivated carbon was porous. We also discussed the performances and theories of theprocess of remove organic pollutants. Langmuir and Freundlich adsorption models wereadopted to explicate the adsorption properties of adsorbates and activated carbon. Theadsorption of activated carbon to Dicamba and Alphanaphthol reached equilibrium after 1 hwith maximum adsorption amount of 173.9 mg/g and 462.4 mg/g, respectively. Adsorption kinetic followed pseudo-second-order reaction kinetic expression. The influences ofadsorbent dosages and the initial concentration of adsorbates on removal was discussed.4. Preparation of TiO₂-mounted Activated Carbon and Photocatalytic Degradation ofDicambaComposite photocatalyst of TiO₂/carbon was prepared by mixing TiO₂ nanoparticleswith active carbon，which was made by waste paper with H3PO₄ activation and microwaveirradiation.The adsorption of dicamba onto the prepared photocatalyst was investigated．Theadsorption isotherm was fitted by Freundlich and Langmuir models. The saturation amountof dicamba adsorbed was estimated to be 101.2mg/g．The photocatalytic degradation ofdicamba under ultraviolet radiation was tested. Compared to the TiO₂ nanoparticles withoutactivated carbon，the composite had higher photocatalytic activity and better separationcharacteristic in sedimentation and filter,which is helpful for the separation of photocatalystfrom liquid phase and reuse.