| Summary: | TiO<sub>2</sub> and TiO<sub>2</sub>-activated carbon (AC) photocatalysts have been prepared (by sol-gel synthesis), characterized, and tested in the removal of diuron from water under simulated solar light. The preparation variables of the two series of catalysts are: (i) heat-treatment temperature of bare TiO<sub>2</sub> (350, 400, 450 and 500 °C) and (ii) activated carbon content (0.5, 1, 5, and 10 wt.%) in TiO<sub>2</sub>-AC samples heat-treated at 350 °C. The activated carbon was previously prepared by hydrothermal carbonization of saccharose and has spherical shape. The heat-treatment temperature does not determine the efficiency of TiO<sub>2</sub> for diuron photocatalytic degradation, but clearly influences the diuron adsorption capacity. The capacity of TiO<sub>2</sub>-AC samples for diuron removal increases with the carbon content and it is the result of combined diuron adsorption and photodegradation. Thus, the sample with highest carbon content (10 wt.% nominal) leads to the highest diuron removal. The TiO<sub>2</sub>-AC photocatalysts have proved to be capable of degrading diuron previously adsorbed in dark conditions, which allows their regeneration.
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