Abstract
Anatase TiO2 is widely used for pollutant degradation due to its photocatalytic property. Exposure of the surface to UV radiation (sunlight or artificial) generates an electron-hole pair that is responsible for the formation of free radicals such as O2•−in the presence of atmospheric oxygen and HO• in the presence of water. Biomorphic TiO2 plates were produced by infiltration of paper with titanium isopropoxide (TTiP) solution followed by hydrolysis in NH4OH and calcination at temperatures up to 600-1000 ºC, as a new way of fixing TiO2 with the aim of delaying the phase transition from anatase (photoactive) to rutile (inactive). In order to study the effect of addition of zirconia as a dopant on the microstructure and the phase transition from anatase to rutile, the same procedure was used, but with the addition of 5% (m/m) of ZrO(NO3)2 to TTiP. The biomorphic materials were characterized by XRD, specific surface area measurement (using the BET method), EPR, and SEM. Their photocatalytic efficiencies were evaluated in the decoloration of Orange II dye and the inhibition of growth of E. coli bioluminescent bacteria. Using 5% Zr-doped TTiP, with calcination at 800 ºC, bacterial growth was reduced by 23% after 180 minutes, and 70% dye decoloration was achieved in30 hours.
Highlights
When the TiO2 anatase structure is exposed to UV radiation, electrons are driven to an electronically excited state
The photocatalytic activity of TiO2 mainly depends on the contents of the anatase and rutile crystalline phases, as well as the specific surface area.[1,2]
The biotemplate method involves the generation of a three-dimensional ceramic material that mimics the morphological structure of an organic matrix, and enables liquid ceramic precursors to be used for infiltrating the organic matrix
Summary
When the TiO2 anatase structure is exposed to UV radiation, electrons are driven to an electronically excited state. There is the formation of reactive free radicals, especially hydroxyl and superoxide, and one electron-hole pair (e/h+) in the valence shell. These features result in an oxidizing material that is capable of degrading organic molecules adsorbed on its surface. The biotemplate method involves the generation of a three-dimensional ceramic material that mimics the morphological structure of an organic matrix, and enables liquid ceramic precursors to be used for infiltrating the organic matrix. Hydrolysis of the precursors, followed by a calcination step for the removal of organics, results in the formation of a ceramic plate with the morphological characteristics of the organic matrix.[3,4,5,6,7]
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