Photocatalytic degradation of p-nitrophenol on nanometer size titanium dioxide surface modified with 5-sulfosalicylic acid

The surface of nanometer size TiO2 was simply and fast modified by chemical adsorption in saturated solution of 5-sulfosalicylic acid. After surface modification, a stable, yellow surface complex was formed quickly, the wavelength response range of TiO2 was expanded, it has obvious absorption in the region from 320 to 450 nm; the adsorption efficiency of p-nitrophenol (PNP) by TiO2 was enhanced from 42% to 84%. The photocatalytic activity was tested on the degradation of PNP. The influences of catalyst and its dosage, pH value, and PNP concentration on the degradation were investigated. On optimal photodegradation conditions, including initial pH 4.0, PNP 5 mg l−1, catalyst 100 mg, irradiation time 120 min with 160 W high-pressure mercury lamp, the degradation efficiency of PNP was increased from 40% to 88% after surface modification. Surface modification led not only to an increase in the light utilization, but also improved the surface coverage of PNP in comparison with the pure TiO2. Both of these factors are crucial for the photocatalytic activity of heterogeneous photocatalysis, especially for photodegradation of benzenoid pollutants.