TiO2 nano-particles were synthesized by sol-gel technique and characterized by X-ray diffractometer (XRD) and transmission electron microscope (TEM). Their photocatalytic activities for formaldehyde (FA) and methyl orange (MO) degradation were tested using degradation rate (η) as an evaluation index. Based on the orthogonal test results, the optimal condition for TiO2 preparation was obtained. Results showed that particle sizes were in the range of 10–40 nm, and that prepared TiO2 had better photocatalytic activity than P25. A simplified model was developed to evaluate the apparent quantum efficiency (Φapp) of this photocatalytic reaction system.
