(224c) Photocatalytic Degradation of Organic Contaminants Using Multifunctional Titanosilicate Ets-10

Authors: 
Ji, Z., Center for Advanced Microgravity Materials Processing , Northeastern University
Warzywoda, J., Northeastern University
Sacco, Jr., A., Northeastern University


Semiconductor photocatalysis has attracted increasing attention in recent years as an alternative to traditional physical, chemical, or biological technologies for environmental remediation. The photocatalyst market is expected to reach US $10 billion in the near future. Engelhard titanosilicate ETS-10 is a microporous (~4.9 Å x 7.6 Å) zeotype material. The well-defined monatomic -O-Ti-O-Ti-O- chains in ETS-10 with a band gap energy of ~4.03 eV make this semiconductor material a promising candidate for photocatalytic applications. ETS-10 has been reported to exhibit shape selectivity during the photodegradation of phenol, 1,3,5-trihydroxybenzene, and 2,3-dihydroxynaphthalene [1]. The photocatalytic activity of ETS-10 after transition metal ion exchange or isomorphous substitution exhibited comparable or even higher activity than Degussa P25, considered a photocatalytic standard [2]. An investigation was performed to design an effective immobilized ETS-10 photocatalytic film or membrane for degradation of organic contaminants. To successfully achieve this project goal, small ETS-10 crystals with an effective diameter of ~690 nm were hydrothermally synthesized using anatase as the Ti source and N-Brand sodium silicate as the Si source. These crystals were then used to prepare ETS-10 films on optical fiber substrates that will be used as the means of light transmission and distribution into ETS-10 photocatalyst. Sol-gel process with a single dip-coating step resulted in nearly complete surface coverage of the optical fibers and an apparent a(b)-out-of-plane preferred orientation of the ETS-10 crystals. The thin film integrity was further improved utilizing a secondary (seeded) growth step for short times (i.e., £4 h). This resulted in high seed crystal intergrowth. In order to evaluate the photocatalytic activity of these ETS-10 thin films, an optical fiber reactor system was designed and optimized. The obtained photocatalytic efficiency will be quantified and compared with that reported for standard TiO2 photocatalyst Degussa P25.

[1]Calza P, Pazé C, Pelizzetti E, Zecchina A. Shape-selective photocatalytic transformation of phenols in an aqueous medium. Chem. Commun. 2001;2130-2131.

[2] Uma S, Rodrigues S, Martyanov IN, Klabunde KJ. Exploration of photocatalytic activities of titanosilicate ETS-10 and transition metal incorporated ETS-10. Micropor. Mesopor. Mater. 2004;67:181-187.