Photocatalytic activity was evaluated by preparing a suspension containing 1 μM p-CBA and 0.667 g L−1 nanoparticles. 15 mL of a suspension was irradiated under the artificial solar light (light intensity of 45 mW cm−2) for 0, 0.5, 1, 2, 4 and 8 h. Particles were filtered through a 0.2 μm filter and fluorescent intensity was measured using HPLC (Agilent 1100 Series quaternary LC) equipped with a photodiode array detector (PDA).