Photocatalytic degradation of Direct yellow 86 diazo dye using sulfanilic acid-modified TiO2 in aqueous suspensions

This study synthesized sulfanilic acid (SA)-modified TiO2 nanocomposites and used them as an effective photocatalyst for Direct yellow 86 diazo dye removal from aqueous solution. This novel nanocomposite (SA/TiO2) was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and X-ray diffraction. The results showed the formation of SA/TiO2 nanocatalyst. The photocatalytic activity of the modified photocatalyst was examined by degradation of Direct yellow 86 (GE) under UV and visible light. The effects of five parameters, the concentration of GE, dosage of SA/TiO2 nanocomposite, UV light irradiation intensity, pH and visible light illumination, on the removal of GE using SA/TiO2 nanocomposite were studied. The highest GE removal was determined at pH of 9, nanocomposite dosage of 0.15 g/l and initial GE concentration of 50 mg/l at the constant temperature of 25 degrees C. However, the results showed that the GE removal rate increased as the UV light intensity increased. In addition, an enhancement in the photodegradation rate was observed with visible light illumination. The adsorption trends of GE at various initial concentrations followed the Langmuir isotherm model.