Photocatalytic Degradation Of Toluene By Activated Carbon Supported Catalyst

Indoor pollution problems have attracted widespread attention with the socio-economic development and people's enhanced awareness of health. Volatile organic compounds (VOCs) are the major indoor pollutants. Photocatalytic degradation of VOCs is the research focus in recent years. TiO₂ was a widely-used photocatalyst due to its high activity, chemical stability, low cost, high oxidation capability and no secondary pollution, etc. But it also has some shortcoming, such as agglomeration, wide band, poor processing efficiency of low concentration gas, etc. Therefore, TiO₂ supported on activated carbon and doping other metal ions can improve the photocatalytic activity. In this paper, TiO₂/AC photocatalysts were prepared by different types of activated carbon and different pore structure of activated carbon; doped Zn²⁺-TiO₂/AC photocatalysts were prepared by sol-gel method. The photocatalysts were characterized by N2 adsorption isotherm, scanning electron microscopy, X-ray diffraction, TG-DSC, etc. Toluene as the target pollutants, it has studied the influence of initial concentration of toluene, add content of catalyst, Zn2 + doping on the photocatalytic activity. The main research results are summarized as follows:1,The preparation methods of activated carbon supported TiO₂ photocatalyst were studied. TiO₂/AC photocatalyst was prepared by sol-gel methods. The influence of sol reaction time, soaking time, activated carbon add content were studied and found the best preparation conditions: (TiOC4H9)4 10 ml, ethanol 15ml, sol reaction time 2 h, the mixture (10 mL anhydrous ethanol, 1.3 mL distilled water, 1 mL acetic acid), activated carbon dosage of 15.61g, dipping 24h, roasting temperature 450℃, TiO₂ loading was 36.59 mg / g.2,TiO₂/AC photocatalysts were characterized by nitrogen adsorption, SEM, XRD, FT-IR, TG-DSC. Nitrogen adsorption shows that activated carbon surface area, pore volume has a certain decrease was mainly due to TiO₂ loaded on the surface and the pore of activated carbon; SEM analysis shows that TiO₂ loaded on the surface of activated carbon is disorganized; XRD analysis shows that the activated carbon helps to reduce the phenomenon of nano-TiO₂ clusters and the crystal form of TiO₂ was similar to anatase; FT-IR analysis shows that the TiO₂ was loaded on AC by chemical bond(Ti-O-C) and combined firmly in the form.3,This paper studied the influence of the experimental conditions, types of activated carbon, structural properties of activated carbon, photocatalysts dosage, initial concentration of toluene on photocatalysts activity. The results show that: TiO₂ photocatalytic degradation under UV light; coconut shell activated carbon is the best, followed by bamboo activated carbon and bamboo carbon; the TiO₂/AC prepared by large surface area and average pore size of activated carbon had higher photocatalytic activity; the catalyst dosage is 3.3 g, the degradation rate of toluene up to 97%; with the initial concentration of toluene increased the degradation rate showed a downward trend; TiO₂/AC extended deactivation time about 4 hours.4,The preparation and photocatalytic activity of the doping-type Zn²⁺-TiO₂/AC were studied. The results show that: Zn²⁺ doping can reduce the grain size of nano-TiO₂; Zn²⁺ doping help to improve the photocatalytic activity of TiO₂/AC which max degradation rate of up to 100% when Zn²⁺ doping content is 20%, after 160min there are still 75% which is 1.8 times to TiO₂/AC; the photocatalysts had the best photocatalytic activity when load times is 2.