Dissertation > Environmental science, safety science > Environmental pollution and its prevention > Atmospheric pollution and its control

UV/VIS Photocatalytic Degradation of Formaldehyde by Bamboo Activated Carbon Supported Catalyst

Author CuiDanDan
Tutor JiangJianChun
School Chinese Academy of Forestry
Course Forest Chemical Process Engineering
Keywords Formaldehyde Bamboo Activated Carbon TiO2/BAC Pt/N/TiO2/BAC Photocatalytic
Type Master's thesis
Year 2011
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Adsorption technology and photocatalytic technologies are showing their respective advantages in formaldehyde water pollution, but they exist inadequacies. In this thesis, the strong adsorption of bamboo activated carbon (BAC) and titanium dioxide (TiO 2 ) photocatalytic oxidation both synergies treatment of the aqueous solution of formaldehyde. Overview of the research based on the use of sol sol - gel prepared TiO 2 the impregnation method will TiO 2 load on the surface of the bamboo activated carbon developed a species of bamboo activated carbon the matrix load TiO 2 Composite UV catalyst (TiO 2 / BAC), prepared at the same time the platinum nitrogen codoped visible light responsive catalyst ( Pt / N / TiO 2 / BAC), and examine both aqueous formaldehyde photocatalytic treatment effect. The main content and research results are summarized as follows: 1, BAC and TiO 2 / BAC Preparation. Bamboo as raw material, was prepared by phosphoric acid activation of different pore sizes and specific surface area of ??the Bamboo activated carbon (BAC) as a carrier. By sol - gel preparation of TiO 2 / BAC, and the degradation of formaldehyde in aqueous solution. The results showed that the bamboo activated carbon adsorption and TiO 2 Photocatalytic Degradation synergies TiO to 2 / BAC photocatalyst significantly improve the processing efficiency of formaldehyde in aqueous solution, and its removal significantly better than a single BAC, single TiO 2 , as well as a mixture of both (mixed) in accordance with the proportion of the composite catalyst in both. Structural characterization of the prepared photocatalyst N2 adsorption results showed that TiO 2 load makes activated carbon specific surface area, pore volume has a certain reduction; SEM analysis showed that TiO 2 activated carbon surface load is disorganized like; XRD analysis shows that the resulting catalyst was prepared polymorphs anatase, and the addition of activated carbon to TiO 2 grain size decreased; FT- IR analysis showed that TiO 2 carbon surface load is combined in the form of chemical bonds (Ti-OC). 2, TiO 2 / BAC of catalytic activity of photocatalyst. Light catalytic activity of the activated carbon nature, light source, pre-adsorption time, amount of catalyst, formaldehyde solution, the initial concentration and pH value of the impact and effects of the repeated use of the catalyst as well as the separation performance. The experimental results show that: the large specific surface area, pore size distribution fit (average pore size in the 2 - 3nm between) bamboo activated carbon as the carrier prepared composite photocatalyst activity; TiO 2 photocatalytic degradation reaction response under ultraviolet light, and the degradation efficiency increased with the UV intensity increases; preadsorbed time can promote the photocatalytic reaction, better play to the synergy of the adsorption and photocatalytic; visits showed that the pH value, the solution in H, OH-ions increases are conducive to the improvement of the degradation rate of formaldehyde; the catalyst added 1.0 g of formaldehyde concentration of 5 mg · L -1 TiO 2 < / sub> load twice when the photocatalytic reaction for 480 min, the highest formaldehyde degradation rate can reach 95% or more; experiment was prepared by the supported photocatalyst TiO 2 / BAC has a good reuse reuse degradation rate is greater than 90% 4 times, and ease of separation; kinetic studies showed that TiO 2 / BAC ultraviolet catalytic removal of the reaction of formaldehyde in aqueous solution in accordance with Langmuir - Xin Wu kinetic equation for a reaction. 3, Pt / N / TiO 2 / BAC Preparation and characterization. SEM analysis showed that the Pt, N codoped favor TiO 2 dispersion of the activated carbon surface. XRD analysis showed that the N, the Pt doping TiO 2 crystal type does not change, N doped TiO 2 from anatase to rutile phase can be suppressed changes, while helping to reduce TiO no significant effect on the catalyst grain size 2 reunion, Pt doping. FT-IR analysis results showed that the surface of the catalyst to generate a Ti-ON chemically. XPS analysis shows that the N Pt through a chemical bond of TiO 2 combining portion N atoms into the TiO 2 lattice may be provided in the heat treatment process, Pt doped on the catalyst surface the gathered electronic center Pt0, surfactant bit Pt0; the O1s peak XPS spectra fitting description of aerobic vacancy exists. UV-Vis analysis showed that: the N doping broadens the the TiO 2 optical absorption range; 2 photocatalytic activity increased Pt doping TiO to. 4, Pt / N / TiO 2 / BAC of visible light catalytic activity investigated. Doping adsorption properties and heat treatment temperature, Pt doping amount of its photocatalytic activity. Experimental results show that: Pt N doping the activated carbon adsorption capacity decreased; Pt, N co-doped with TiO 2 / BAC photocatalytic response range conducive to extend to a visible region, and has a high photocatalytic activity. When the heat treatment temperature of 500 ° C, Pt doping amount of 1.0%, the best degradation effect, the reaction after 315 min of the highest degradation rate reached 64.01 percent and TiO 2 / BAC corresponding formaldehyde in addition, for the same conditions 2.6 times the rate of solution and good separation, is conducive to the recycling of the catalyst.

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