Surface sulfate modified TiO2 visible light active photocatalyst for complex wastewater purification: Preparation, characterization and photocatalytic activity

Abstract

One of the major concerns of today's society is the rapid deterioration of our environment. Wastewater purification via catalysts could be a solution for a part of this situation. Related to this topic. Related to this topic here we report the facile preparation of surface-modified TiO2 photocatalyst performed by simply grinding and calcination process, using elemental sulfur originated from the desulfurization of petroleum.Visible light active (Eg = 2.91 eV) sulfur modified TiO2 were prepared with low surface charge (-62.2 ± 0.7 mV). The improved photocatalytic activity of sulfated samples was proved via benzoic acid photodegradation tests under visible light and compared to the reference P25. According to the results, the sulfated TiO2 degraded 41% of the initial benzoic acid, while TiO2 degraded only 27%. Next mechanically stable photoreactive composite layers were prepared using the ST-benzene catalyst and it was presented that the thin film can successfully degrade the model water. In the complex sample, the ST-benzene containing photocatalyst layer's efficiency was 25.3% for phenol, 20.3% for niacin, 30.0% for paracetamol, 10.6% for caffeine and 28.8% for imidacloprid respectively. In addition, it is also presented that the sulfated photocatalyst is able to generate more hydroxyl radicals (which depends on the reaction rate constant of 7-hydroxycoumarin formation, kST-benzene = 6.682×10−5 µmol×L−1 × s−1) than the initial P25 TiO2, which makes it a promising photocatalyst for water purification.