Diatom silica–titania photocatalysts for air purification by bio-accumulation of different titanium sources

摘要: We present a green, biological production route for silica–titania photocatalysts using diatom microalgae. Diatoms are single-celled, eukaryotic microalgae (2–2000 μm) that self-assemble soluble silicon (Si(OH)4) into intricate silica cell walls, called frustules. These frustules formed under ambient conditions and consist of hydrated with specific 3D morphologies micro–meso or macroporosity. A remarkable characteristic diatoms is their ability to bioaccumulate titanium from culture medium incorporate them nanostructured wall. Controlled cultivation the Pinnularia sp. on in batch process resulted immobilisation dioxide porous architecture Six different sources tested. The were isolated by treating harvested cells nitric acid (65%) high temperature treatment. Thermal annealing converted amorphous titania crystalline titania. produced material evaluated towards photocatalytic activity acetaldehyde (C2H4O) abatement. Frustules cultivated TiBaldH showed highest performance. Comparison P25 reveals has 4 fold higher activity, but when normalized content, show double activity. Further characterization (morphology, crystallinity, surface area elemental distribution) provides additional insight structure–activity relationship. natural biosilica–titania materials have excellent properties purposes, including (108 m2 g−1) good porosity, reliable immobilization TiO2 ordered structure frustule.