The Photo-Oxidation of Primary Alcohols by Anatase

When primary alcohols are u.v. irradiated in presence of anatase, with nitrogen flowing, the alcohol is expected to be oxidised to aldehyde and Ti(III) is expected to be formed in the suspension and at the surface of the powder. This is an example of a photoredox heterogeneous reaction (Prog.Org.Coatings, 1, (1972) 157). 

Calculate the number of mols of Ti formed from the titre and from the standardisation of the I2 solution. An independent l2/Na2S203 titration gives the exact 

Repeat the irradiation and titration replacing methanol by ethanol, i-propanol or n-butanol. Using the latter alcohol, repeat using irradiation times of 2 or 3 hours. Keeping irradiation time to 1 hour, using anatase concentrations = 2,3 or 4 times the previous 1% (w/v). 

Examine the appearance of the irradiated P25 and note the change after leaving in air for a few days. Comment on your results and your observations. 

Like other insoluble compounds, the surface of Ti02, suspended in water is known to be hydroxylated. The surface equilibria can be represented by  

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