Comparison of Photocatalytic Activities of Commercial Titanium Dioxide Powders Immobilised on Glass Substrates

Semiconductor photocatalysis is an advanced oxidation technology reported to be effective for the degradation of a wide range of organic pollutants found in water. Titanium dioxide is the most suitable photocatalyst for water treatment as it is insoluble under normal pH conditions, is photoactive, photostable, readily available and inexpensive. In this work Millennium Chemicals PC500, PC105, PC100, PC50, PC10 and Evonik Degussa P25 powders were immobilised onto borosilicate glass, via dip-coating and spray coating, producing thick films ranging from 0.2 to 1.4 mg catalyst per square cm of glass substrate. The photocatalytic activity of the immobilised films was compared under back-face UVA irradiation in a stirred-tank reactor using formic acid and phenol as model pollutants. Based upon the rate constant derived from the removal of the parent compound, and using the optimum catalyst loading determined under the experimental conditions employed, the order of photocatalytic activity for the degradation of formic acid was found to be P25 > PC100 > PC50 > PC105 ≥ PC500 > PC10, while for phenol degradation the order was P25 > PC50 > PC105 > PC100 ≥ PC500 > PC10