Goworek, J., Derylo-Marczewska, A. and Borowka, A., "Adsorption from the liquid phase on silica gels of various structural heterogeneity," Langmuir, Vol. 15, pp. 6103-6106, 1999. Grabner, G., Li, G., Quint, R., Quint, R. and Getoff, N., "Pulse laser-induced oxidation of phenol in acid aqueous TiO2," Journal of the Chemical Society Faraday Transactions, Vol. 87, pp. 1097-1101, 1991. Grieken, R., Aguado, J., Lopez-Munoz, M. and Marugan, J., "Synthesis of size-controlled silica-supported TiO2 photocatalysts," Journal of Photochemistry and Photobiology A: Chemistry, Vol. 148, pp. 315-322, 2002. Halmann, M., Photodegradation of Water Pollutants, CRC Press, Boca Raton, 1996. Hanprasopwattana, A., Srinivason, S., Sault, A. and Datye, A., "Titania coatings on monodisperse silica spheres: characterization using 2-propanol dehydration and TEM," Langmuir, Vol. 12, pp. 3173-3179, 1996. Hench, L. and West, J.," The sol-gel process," Chemical Review, Vol. 90, pp. 33-72, 1990. Hoffman, M., Martin, S., Choi, W. and Bahnemann, D., "Environmental application of semiconductor photocatalysis," Chemical Reviews, Vol. 95, pp. 69-96, 1995. Hoigne, J., "Formulation and calibration of environmental reaction kinetics; oxidations by aqueous photooxidants as an example," in: Aquatic Chemical Kinetics, Stumm, W. (Ed.), John Wiley & Sons, Inc., New York, pp. 43-70, 1990. Holysz, L., "The effect of thermal treatment of silica gel on its surface free energy components," Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 134, pp. 321-329, 1998. Houas, A., Lachheb, H., Ksibi, M., Elaloui, E., Guillard, C. and Hermann, J., "Photocatalytic degradation pathway of methylene blue in water," Applied Catalysis B: Environmental, Vol. 31, pp. 145-157, 2001. Iler, R., The Chemistry of Silica, John Wiley & Sons, New York, 1979. Jackson, N., Wang, C., Luo, Z., Schwitzgebel, J., Ekert, J., Brock, J. and Heller, A., "Attachment of TiO2 powders to hollow glass microbeads: activity of the TiO2- coated beads in the photoassisted oxidation of ethanol to acetaldehyde," Journal of the Electrochemical Society, Vol. 138, pp. 3660-3664, 1991. Jung, K. and Park, S., "Enhanced photoactivity of silica-embedded titania particles prepares by sol-gel process for the decomposition of trichloroethylene," Applied Catalysis B: Environmental, Vol. 25, pp. 249-256, 2000.