The Photocatalysed Removal of Lead Ions from Solution

14 THE PHOTOCATALYSED REMOVAL OF LEAD IONS FROM SOLUTION When the photocatalyst anatase is suspended in lead(Il) acetate solution and the suspension is irradiated by a u.v. source, it is expected that the photoexcited electrons in the conduction band of the catalyst would reduce lead ions in solution, whereas the holes generated in the valence band would react at the surface forming OH radicals. These are likely to oxidise the acetate ions to CO2. 

To follow the progress of the photocatalysed reaction, withdraw samples of the suspension at intervals, centrifuge and filter. Titrate an aliquot of the filtrate with EDTA and hence calculate the concentration of lead not lost. Plot this against the time of withdrawal of the aliquot. 

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