Nanocrystalline TiO2 Photocatalytic Membranes with a Hierarchical Mesoporous Multilayer Structure: Synthesis, Characterization, and Multifunction

A novel sol–gel dip-coating process to fabricate nanocrystalline TiO2 photocatalytic membranes with a robust hierarchical mesoporous multilayer and improved performance has been studied. Various titania sols containing poly(oxyethylenesorbitan monooleate) (Tween 80) surfactant as a pore-directing agent to tailor-design the porous structure of TiO2 materials at different molar ratios of Tween 80/isopropyl alcohol/acetic acid/titanium tetraisopropoxide = R:45:6:1 have been synthesized. The sols are dip-coated on top of a homemade porous alumina substrate to fabricate TiO2/Al2O3 composite membranes, dried, and calcined, and this procedure is repeated with varying sols in succession. The resulting asymmetric mesoporous TiO2 membrane with a thickness of 0.9 μm exhibits a hierarchical change in pore diameter from 2–6, through 3–8, to 5–11 nm from the top to the bottom layer. Moreover, the corresponding porosity is incremented from 46.2, through 56.7, to 69.3 %. Compared to a repeated-coating process using a single sol, the hierarchical multilayer process improves water permeability significantly without sacrificing the organic retention and photocatalytic activity of the TiO2 membranes. The prepared TiO2 photocatalytic membrane has great potential in developing highly efficient water treatment and reuse systems, for example, decomposition of organic pollutants, inactivation of pathogenic microorganisms, physical separation of contaminants, and self-antifouling action because of its multifunctional capability.

[1]  Takayuki Kitamura,et al.  Dependence of TiO2 Nanoparticle Preparation Methods and Annealing Temperature on the Efficiency of Dye-Sensitized Solar Cells , 2002 .

[2]  R. Caruso,et al.  Inorganic Macroporous Films from Preformed Nanoparticles and Membrane Templates: Synthesis and Investigation of Photocatalytic and Photoelectrochemical Properties , 2003 .

[3]  P. Albouy,et al.  Mesostructure of Anatase Thin Films Prepared by Mesophase Templating , 2004 .

[4]  Henk Verweij,et al.  Improved performance of silica membranes for gas separation , 1998 .

[5]  D. Dionysiou,et al.  Synthesis of anatase nanostructured TiO2 particles at low temperature using ionic liquid for photocatalysis , 2005 .

[6]  N. Coombs,et al.  Solventless Acid‐Free Synthesis of Mesostructured Titania: Nanovessels for Metal Complexes and Metal Nanoclusters , 2003 .

[7]  M. Antonietti,et al.  Titania and Mixed Titania/Aluminum, Gallium, or Indium Oxide Spheres: Sol–Gel/Template Synthesis and Photocatalytic Properties , 2005 .

[8]  L. Wu.  Effects of sol properties and calcination on the performance of titania tubular membranes , 2000 .

[9]  Kai Zhang,et al.  Influence of cross-flow velocity on membrane performance during filtration of biological suspension , 2005 .

[10]  S. Kwak,et al.  Hybrid organic/inorganic reverse osmosis (RO) membrane for bactericidal anti-fouling. 1. Preparation and characterization of TiO2 nanoparticle self-assembled aromatic polyamide thin-film-composite (TFC) membrane. , 2001, Environmental science & technology.

[11]  J. Laîné,et al.  Effect of oxygen in a thin-film rotating disk photocatalytic reactor. , 2002, Environmental science & technology.

[12]  G. Owen,et al.  Economic assessment of membrane processes for water and waste water treatment , 1995 .

[13]  T. Sanders,et al.  Thermodynamic Modeling of the Miscibility Gaps and the Metastable Liquidi in the MgO‐SiO2, CaO‐SiO2, and SrO‐SiO2 Systems , 1999 .

[14]  I. Yeom,et al.  Pilot plant study of an ultrafiltration membrane system fordrinking water treatment operated in the feed-and-bleed mode , 2005 .

[15]  D. Dionysiou,et al.  Ionic liquid assisted preparation of nanostructured TiO2 particles. , 2004, Chemical communications.

[16]  Wilhelm F. Maier,et al.  hydrophobic silica membranes for gas separation , 1999 .

[17]  Kai Zhang,et al.  Effect of Permeate Flux and Tangential Flow on Membrane Fouling for Wastewater Treatment , 2005 .

[18]  Bradley F. Chmelka,et al.  Block Copolymer Templating Syntheses of Mesoporous Metal Oxides with Large Ordering Lengths and Semicrystalline Framework , 1999 .

[19]  P. Albouy,et al.  A Simple Route for Low-Temperature Synthesis of Mesoporous and Nanocrystalline Anatase Thin Films , 2003 .

[20]  D. Blake,et al.  Photocatalytic oxidation of bacteria, bacterial and fungal spores, and model biofilm components to carbon dioxide on titanium dioxide-coated surfaces. , 2002, Environmental science & technology.

[21]  A. Neimark,et al.  Density Functional Theory of Adsorption in Spherical Cavities and Pore Size Characterization of Templated Nanoporous Silicas with Cubic and Three-Dimensional Hexagonal Structures , 2002 .

[22]  J. Crittenden,et al.  Preparation of a novel TiO2-based p-n junction nanotube photocatalyst. , 2005, Environmental science & technology.

[23]  J. Raulin,et al.  Heterogeneous photocatalysis: state of the art and present applications In honor of Pr. R.L. Burwell Jr. (1912–2003), Former Head of Ipatieff Laboratories, Northwestern University, Evanston (Ill). , 2005 .

[24]  Jackie Y. Ying,et al.  SYNTHESIS AND APPLICATIONS OF SUPRAMOLECULAR-TEMPLATED MESOPOROUS MATERIALS , 1999 .

[25]  A. Henglein.  Colloidal TiO2 Catalyzed Photo‐ and Radiation Chemical Processes in Aqueous Solution , 1982 .

[26]  Kyong-Sop Han,et al.  Preparation and thermal stability of doped TiO2 composite membranes by the sol–gel process , 1998 .

[27]  Y. S. Lin.  Microporous and dense inorganic membranes: Current status and prospective , 2000 .

[28]  Jackie Y. Ying,et al.  Role of Particle Size in Nanocrystalline TiO2-Based Photocatalysts , 1998 .

[29]  Y. S. Lin,et al.  Synthesis and Characterization of Suspension-Derived, Porous Ion-Conducting Ceramic Membranes , 2004 .

[30]  X. Tan,et al.  Odor control using hollow fiber membrane modules , 2005 .

[31]  Chuncheng Chen,et al.  Photocatalysis by titanium dioxide and polyoxometalate/TiO2 cocatalysts. Intermediates and mechanistic study. , 2004, Environmental science & technology.

[32]  T. Maschmeyer,et al.  Mesoporous Membranes—A Brief Overview of Recent Developments , 2004 .

[33]  C. Tsakiroglou,et al.  Highly efficient nanocrystalline titania films made from organic/inorganic nanocomposite gels , 2004 .

[34]  Z. Deng,et al.  The synthesis of nanocrystalline anatase and rutile titania in mixed organic media. , 2001, Inorganic chemistry.

[35]  C. Vandecasteele,et al.  Alumina and titania multilayer membranes for nanofiltration: preparation, characterization and chemical stability , 2002 .

[36]  C. Brinker,et al.  Template-Based Approaches to the Preparation of Amorphous, Nanoporous Silicas , 1996 .

[37]  Yunfeng Lu,et al.  Dual-Layer Asymmetric Microporous Silica Membranes , 2000 .