Study On The Nano-TiO₂ Photocatalytic Reactor And Its Degradation Of Formaldehyde In The Air

For the excessive use of chemicals, it made the indoor air pollution to be the focus of widespread concern. People made lots of useful exploration on the treatment of indoor air pollution. And Photocatalytic Air Purification technology as a new kind of highly effective air purification technology had became the hot spot in domestic and foreign research. In the photocatalytic materials, Titanium dioxide (TiO₂), by the advantages of non-toxic, high catalytic activity, good stability and so on, obtained the widespread application.In this paper, the photocatalytic degeneration of formaldehyde in the air experimental study was carried out in the designed cylindrical fixed bed type photocatalytic reactor, with photocatalysts specially made by Nano-TiO₂ loaded on porous glass carrier. Using methods such as TEM, XRD, TG-DTA, ultraviolet -obvious dispersion of light luminosity, electrochemistry and so on, the crystal structure, paticle size, superficial appearance, the optical property and the formaldehy dedegeneration capability of the photocatalytic reactor were investigated. The results indicated that, the crystal TiO₂ distributed symmetrically on the carrier surface, presented sintered crystal film; the particle size is in the range of 7-20nm; the superficial appearance is neat, the optical property is good. With the current capacity range between 0.1-0.7m³/h, the entering tower gas concentration between 0.54 -3.28 mg/m³, the photocatalytic reaction experimental result is ideal, in this condition, the degeneration rates are distributed in the range of 40%-95%; while the current capacity is 0.3 m³/h, and the entering tower gas concentration is 0.54 mg/m³, the degeneration rate is the highest, it's 94.4%.And further experimental study was did on the TiO₂ photocatalytic degradation formaldehyde kinetics under several kind of different concentrations, the experimental data results conformed to the first-level reaction kinetics equation, photocatalytic degradation process reaction rate followed the non-homogeneous phase catalysis dynamic equation - Langmuir-Hinshelwood equation. The kinetics equation expression is: 1/r₀ = 29.231/C₀ + 6.6369, its speed constant k=0.1507mg/m³ min; adsorption equilibrium constant K_A=0.227m³/mg.