Photocatalytic removal of Pb(II) over TiO2 and Pt–TiO2 powders

Results on Pb(II) photocatalytic removal using TiO2 and Pt-loaded TiO2 under different conditions shed light on the mechanisms of previous reports on this complex system. Efficiencies are dependent on the reaction conditions and on the type of photocatalyst. Low efficiency is obtained when only pure TiO2 is used. The reaction is enhanced: (1) using platinized TiO2, (2) bubbling ozone, and (3) by addition of 2-propanol. Different mechanisms, via reductive and oxidative pathways, can be proposed for each experimental condition. The nature of the lead deposits depends on the reaction conditions, and supports the proposed mechanisms.