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Composite nanostructured samples of Ag (0.5-20%)/(C, S)-TiO(2) were synthesized and characterized by EDX, XRD, FT-IR, UV-vis, BET, XPS, and zeta potential measurements. Photocatalytic and biocidal tests revealed that the amount of the codoped silver (Ag(+)) in (C, S)-TiO(2) played a crucial, distinctive role in the photodegradation of gas-phase acetaldehyde as well as in the inactivation of Escherichia coli cells and Bacillus subtilis spores. Very interestingly, Ag/(C, S)-TiO(2) nanoparticles (crystallite size <10 nm) have shown very strong antimicrobial properties without light activation against both E. coli (log kill >8) and B. subtilis spores (log kill >5) for 30 min exposures, compared with P25-TiO(2). Thus, for the first time, we have demonstrated that titanium dioxide (an environmentally friendly photocatalyst) codoped with silver, carbon, and sulfur can serve as a multifunctional generic biocide as well as a visible light activated photocatalyst.

CobaltÀcarbonÀsulfur-codoped anatase photocatalysts (size <9 nm) were synthesized by hydrolyzing titanium(IV) isopropoxide in the presence of cobalt salts and ammonium thiocyanate at room temperature. The annealed photocatalysts were characterized with nitrogen adsorp-tionÀdesorption isotherms, energy-dispersive X-ray (EDX), X-ray diffraction (XRD), UVÀvisible diffuse reflectance, transmission electron microscopy (TEM), X-ray photon spectroscopy (XPS), and photoluminescence (PL) measurements. Characterization results showed that the doped cobalt, carbon, and sulfur of the TiO 2 photocatalysts have some beneficial effects on specific surface area, visible light absorption, hydroxyl radical generation, and electronÀhole pair separation. For the acetaldehyde degradation reaction, the activity of the photocatalysts follows the order 2% Co(III)/(C, S)ÀTiO 2 ≈ 2% Co(II)/(C, S)ÀTiO 2 > 1% Co(II)/(C, S)ÀTiO 2 > 2% Co(II)ÀTiO 2 > 2% Co(III)ÀTiO 2 > (C, S)ÀTiO 2 under visible light and 2% Co(II)/(C, S)ÀTiO 2 > 1% Co(II)/(C, S)ÀTiO 2 > 2% Co(II)ÀTiO 2 ≈ (C, S)ÀTiO 2 > TiO 2 ÀP25 under UV light. It was concluded that the doped cobalt ions play a vital role and act as active sites in the photodegradation reaction. A reaction mechanism is proposed that may explain the synergistic effect of the codopants in visiblelight-induced photodegradation of acetaldehyde. This new photocatalyst system, Co/(C, S)ÀTiO 2 , can have other potential applications that only need visible light as energy input.

A series of solid sorbent materials, including alumina (Al 2 O 3 ), magnesia (MgO), titania (TiO 2 ), silica (SiO 2 ), and carbon, of widely varying physical properties, have been studied as sorbents for two toxic substances: sulfur dioxide gas (SO 2 ) and chemical warfare surrogate 2-chloroethyl ethyl sulfide (2-CEES, ClCH 2 CH 2 SCH 2 CH 3 ). Sorbent surface areas, average pore sizes, pore volumes, surface hydroxyl groups, and nitrogen adsorption-desorption isotherms were measured. Surface areas varied from 18 m 2 /g to over 1000 m 2 /g, pore volumes from 0.04 to 1.2 cm 3 /g, and pore diameters from 1.7 to 4.9 nm. Breakthrough studies of SO 2 and 2-CEES sorption yielded information about the effectiveness of each sorbent. Carbon samples worked well for 2-CEES but not SO 2 , while silica samples were poor for both. The best MgO and TiO 2 samples were good for both SO 2 and 2-CEES, and overall, the highest surface area (459 m 2 /g) TiO 2 sample was the superior sorbent. The important features for an effective sorbent under the conditions employed are high surface area and high pore volume, possessing isolated surface -OH groups, mesoporous nature, and a polar surface (Lewis base and Lewis acid sites).