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

Abstract

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.

Supported TiO2 on Borosilicate Glass Plates for Efficient Photocatalytic Degradation of Fenamiphos

“…2 . TiO 2 was immobilised on borosilicate glass using spray coating technique [18,23]. This is a simple and effective means to produce coatings on conducting and nonconducting supporting substrates.…”

“…A custom-built stirred tank photoreactor (STR), previously reported [18,23,24], was used in this study. The closed system consisted of a water-jacketed walled vessel reservoir and a stainless steel propeller in order to create a turbulent flow.…”

“…Degussa P25 contains a small rutile core surrounded by anatase crystallites. According to this structure, the high photocatalytic efficiency has been attributed to catalytic "hot spots" at the intersection of the two phases due to the unique surface chemistry [18].…”

“…Also, it was found that the optimum catalyst loading was around 1 mg cm −2 and, above this loading, low increase in the rate of degradation was observed. For higher quantities of catalyst, the reaction kinetic decreases because of the saturation of photons absorption [11,18,23,24]. Figure 7 shows the kinetic curve of degradation of fenamiphos in the presence of P25 catalyst supported on glass with different concentrations of fenamiphos (4, 6, 10, and 15 ppm); the initial pH was of 5.8.…”

“…The Degussa P25 TiO 2 -type is a commercially available powder preparation and has emerged as the research standard in the field of photocatalysis. However, since the final filtration of titania powders in suspension for the release of cleaned water and the recovery of the catalysts is a tedious process, titania has been successfully deposited on different supports [18][19][20][21][22][23][24].…”