Processing Technics And Photocatalysis Of Wood-based Nano-composite

Wood-based nano-composite was prepared by the fast-growing poplar treated with porous material bamboo charcoal and nano-TiO₂. Firstly, preparing mechanics, pore structural and photocatalytic performance of the intermediate of TiO₂/bamboo charcoal composite was studied. Secondly, the bonding strength and moisture adsorption mechanism of wood-based nano-composite was tested and analyzed. Finally, the mathematical model of photocatalytic degradation of formaldehyde was established, the rules of synergetic effect of evaporate and photocatalytic degradation was defined. The results showed:(1) The photocatalytic activity of TiO₂/bamboo charcoal composite was evaluated using phenol as a model substrate and the optimal load was identified, which was 3%. It was found that the Langmuir–Hinshelwood model in its integral form in describing the fraction order kinetics of phenol photocatalytic degradation in the TiO₂/bamboo charcoal composite were better than its simplified form as a first-order reaction model, the corresponding photocatalytic degradation reaction equation is: lnC-0.0077C=6.58-0.00239t. The equation of photocatalytic degradation rateηand illumination time t of TiO₂/bamboo charcoal composite with 3% load is: ln(1-η)+1.38η=3.4-0.00239t.(2) The TiO₂/bamboo charcoal composite with 3% load was selected as research object. The pore structure, morphology and crystallographic texture of TiO₂/bamboo charcoal composite were evaluated by instrumental analysis techniques with BET, SEM, XRD.a) The surface area, total pore volume and average pore diameter of TiO₂/bamboo charcoal composite were 359.81m²/g, 0.3172cm³/g and 3.53nm.b) The mesopore structural parameters and mesopore diameter distribution curves of the photocatalyst were derived from the Barret?Joyner?Halenda (BJH) model. The surface area, accumulation pore volume and pore diameter of TiO₂/bamboo charcoal composite were 139.281m²/g, 0.246 cm³/g and 5.80 nm. The results showed that the photocatalyst had more cumulative volume of pores than bamboo charcoal by 65.86%, and pore diameter was narrowly distributed at the range of 3.15⁴.4nm, which was wider than bamboo charcoal(3.13³.89nm).c) TiO₂/bamboo charcoal composite was characterized by using XRD. The results indicate that it has X-ray diffraction peak in diffraction angle 2θwith25.34°, 37.84°, 48.04°, 54.08°, 55.06°nearby. The diffraction peak has a little change toward big angle, the crystal structure of TiO₂ was not changed, and remained the photocatalytic properties of nano-TiO₂.(3) Methods by L9(33) orthogonal design, with the bonding strength of wood-based nano-composite as the main evaluation index. The best process parameters for the production were also presented combined with analyzed by SEM. The optimal process parameters are: pressing pressure is 1.2 MPa, impregnated pressure is 1.6 MPa, adhesive usage is 200g/m².(4) The bonding strength of wood-based nano-composite is smaller than poplar plywood, with poplar plywood is 1.16MPa and nano-composite is 0.88 MPa.(5) XPS was applied to analyze the surface chemical composition and structure of the poplar veneer treated by nanocomposites. It was detected that the surface have C, O, and N, with a little titanium, which is TiO₂ with content of 3.08% decteted by XPS wide-scan spectra and high resolution.(6) The moisture adsorption of poplar veneer, poplar veneer treated by nanocomposites and wood-based nano-composite were studied by Dent model. The model parameter M0 which is the moisture contents corresponding to complete monolayer coverage of all available sorption sites are 7.08%,6.98% and 6.79% separately. The moisture adsorption of poplar veneer is the most strongest among three materials, moisture adsorption of the wood-based nano-composite is the lowest.(7) Allow for the formaldehyde volatilization of wood-based nano-composite, its mathematic model with interaction of volatilization and photocatalysis has been established. The trends of formaldehyde concentration in environment can be very well simulated . The model equation is:...