Study Of Mn-doped TiO₂ Loaded Wood-based Activated Carbon Fibers As Packaging Materials

Mn-doped TiO2 nanocrystal photocatalysts(Mn/TiO2), Mn-doped and Mn N co-doped TiO2 colloids were prepared by sol-gel method. Mn-doped and Mn N co-doped TiO2 loaded wood-based activated carbon fibers(Mn/TiO2-WACF、Mn/TiO2-N-WACF) were prepared by impregnation method. The photocatalytic composite materials were characterized by SEM, XRD, FITR, BET, XPS, et al.Their photocatalytic activity for methylene blue (MB) degradation was investigated. The effects of different factors on photocatalytic degradation of formaldehyde using Mn/TiO2-WACF under visible light were studied in order to reduce the harmful gases content of formaldehyde in the packages, also improve product packaging performance for reference.(1)The growth of particle size of TiO2 powder was suppressed by doping Mn. The size of TiO2 nanoparticle and visible light absorption properties gradually decreased with Mn doping concentration increasing.8 hours later, the methylene blue(MB) photodegradation rate of Mn-doped TiO2 improved by 46% than that of the undoped TiO2.(2) Mn-doped TiO2 was loaded on the surface of wood-based activated carbon fiber like a film, and there is still a wealth of exposed fiber pore structure. As the doping amount of Mn to increase the infrared absorption spectrum peak of Ti-O-C enhanced, specific surface area, pore volume decreased significantly, but still up to 1238.7 m2/g,0.628cm3/g, average pore diameter of 2nm, containing a large number of micropores and a small amount the mesoporous. After light irradiation for 4h, the degradation rate of methylene blue by Mn/600Ti-WACF samples reached the maximum of 96%, higher than that of pure TiO2 by 73%.(3)The transformation temperature of Mn-doped TiO2 from anatase tu rutile increases to 650℃-750℃. As increasing of calcination temperature, the anatase particle size (26-47nm) has an increasing trend, the hydroxyl group on behalf of the strong oxidizing properties first decreases and then increases, the proportion of micropores is reduced, the specific surface area and pore volume of Mn/Ti-WACF (in addition to the sample of 650℃) were lower than WACF, but still up to 1477.7 m2/g,0.734cm3/g, an average pore diameter of about 2nm. After 280min, the degradation rate of methylene blue by samples (calcination temperature 450℃) reached the maximum of 93%.(4) Under the calcination condition of 450℃, Mn in the photocatalytic composites substituted some Ti4+ in TiO2 lattice; N substituted some oxygen anions in TiO2 lattice. After light irradiation for 4h, the degradation rate of methylene blue by Mn/50Ti-WACF samples reached the maximum of 95%, higher than that of pure TiO2 by 72%.(5)Mn/TiO2-N-WACF diameter (23-33nm) increases with increasing temperature, transformation temperature from anatase to rutile is about 650℃-750℃. As the calcination temperature increases, the titanium, manganese and nitrogen content first increases and then decreases, the absorbance first increases and then decreases, fluorescence intensity first decreases and then increases, the degradation of methylene blue first increases and then decreases. After 120min, the degradation rate of methylene blue by samples (calcination temperature 550℃) reached the maximum of 99%.(6)With increased lighting time, Mn/TiO2-WACF doses and initial formaldehyde concentration, the degradation rate of formaldehyde increased gradually. With increased Mn doping concentration and illumination intensity, the degradation rate of formaldehyde first increased and then decreased. When 65 W spiral energy saving lamp lighting 4h, initial formaldehyde concentration of 9.38mg/L, n(Mn):n(Ti)=1:100, Mn/TiO2-WACF doses of 0.22g, the degradation rate of formaldehyde reached 91%.