Improved performance and prolonged lifetime of titania-based materials: sequential use as adsorbent and photocatalyst

Lifetime is a key index in the evaluation of environmentally functional materials. Although it is well known that adsorption is the first step in photocatalysis, very little work has been done on the sequential use of materials as both adsorbents and photocatalysts. In this work, two titania-based materials, Ti O2 xerogel and Ti O2 photocatalyst nanoparticles, were fabricated and evaluated as adsorbent and photocatalyst for the remediation of contaminated water with an azo dye, Acid Orange 7(AO7), as the modeling pollutant. The Ti O2 xerogel showed a high adsorption capacity to AO7(769 mg/g) and could be regenerated easily with diluted Na OH solution(0.01 mol/L) for several cycles. The exhausted xerogel was calcined at 400 °C for 3 h and used as a photocatalyst for the degradation of AO7. Compared to the nanoparticles directly prepared from fresh Ti O2 xerogel, the Ti O2 nanoparticles from adsorption exhausted xerogel showed a much higher photocatalytic activity upon both UV and visible light irradiation. Thus the titania-based materials were endowed with improved performance as well as prolonged lifetime.