IMAGING SCIENCE AND PHOTOCHEMISTRY

The Effects of Tourmaline Powders on the Preparation of Nano-TiO₂ and Photocatalytic Oxidation of Toluene in Air

LIU Li-fen, SUN Meng-jun, YANG Feng-lin

2008, 26(3): 177-185. DOI: 10.7517/j.issn.1674-0475.2008.03.177

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The tourmaline powders (400 mesh) was either mixed to the sol during sol-gel preparation or with P-25 suspension to coat stainless steel net. The mixed coating on the stainless steel net was calcinated, the supported catalysts surface structure is investigated by X-ray diffraction(XRD),scanning electron microscope (SEM)and transmission electron microscopy,the photo-catalytic activity of the catalysts(on 3 cm?15 cm stainless steel net) was determined by photocatalytic degradation of toluene in air with 20 W germicidal UV lamp in a static reactor(14 L). The effect of the tourmaline powders on the catalyst crystal size during TiO₂ preparation using sol-gel method was studied. The results show that the tourmaline powder is beneficial to the preparation of smaller sized TiO₂ nano-crystal, which in combination with the coherent electric field of tourmaline improved the catalytic activity of the supported catalyst. By using the sol gel prepared T-TiO₂-1 catalyst, about 87% toluene removal was obtained when initial concentration was 180 mg·m^-3, and about 82% toluene removal was obtained when initial concentration was 70 mg·m^-3 after 4 hours reaction. The average activity of composite catalyst film on stainless steel net for toluene removal prepared via sol gel method was 1.90 mg·m^-2·min^-1 or 0.11 mg·g^-1·min^-1, while using the T-TiO₂-2 catalyst, about 58% toluene removal was obtained when initial concentration was 180 mg·m^-3, and about 42% toluene removal was obtained when initial concentration was 70 mg·m^-3 after 4 hours reaction. The average activity of composite catalyst film on stainless steel net for toluene removal prepared via sol gel method was 1.35 mg·m^-2·min^-1 or 0.18 mg·g^-1·min^-1.

LC-ESI-MS Study of the Photo-Polymerization Products of Triclosan

CHEN Zhong-liang, SONG Qi-jun

2008, 26(3): 186-192. DOI: 10.7517/j.issn.1674-0475.2008.03.186

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The safety of triclosan in the daily-used chemical products has evoked a great deal concern in the academic community due to the possible formation of dioxin in the photo-induced transformation. The photo-polymerization(PPM)of triclosan under UV irradiation and effects of light sources were investigated by using LC-ESI-MS and HPLC. By analyzing the ion chromatogram for different m/z at negative ion mode,three kinds of products (total seven PPM products) with molecular ion 505,540 and 794 respectively were identified. The numbers of their isomers respectively were 2、3 and 2. These compounds were formed by removal of HCl among triclosan molecules or loss of chloride anions. 2,8-dichlorodibenzo-p-dioxin transformed by ring-closure of triclosan was also detected in the photolysed products. The light source effects on the formation of PPM products were also investigated by utilizing the HPLC analysis. It was found that the PPM reaction was strongly affected by the light source,and the UVB was much more effective than the UVA.

Synthesis and Character Study of Two New Type of F^- Fluorescence Chemosensors

YANG Yun-xu, DENG Xiao-rong, JI Xing-yue, SUN Zhen, QIN Li-juan

2008, 26(3): 193-199. DOI: 10.7517/j.issn.1674-0475.2008.03.193

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Two sulfamide host compounds (I, Ⅱ) were synthesized and their fluorescence character was studied. Through the study of their recognition with Cl^-, Br^-, NO₃^-, NO₂^-, HSO₄^-, Ac^- and F^- anions in CH₃CN, it was found that both of the hosts have a selective recognition with F^-. An exciplex formed by the addition of F^-, in which the fluorescence intensity of compound I, Ⅱ at 317 nm decreases and a new broad emission band peaked at 403 nm emerges with increasing intensity.

Biomimetic Synthesis of Acicular Nanometer HgS in the Gelatin Solution

TANG Shi-hua, HUANG Zai-yin

2008, 26(3): 200-205. DOI: 10.7517/j.issn.1674-0475.2008.03.200

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HgS acicular nanocrystals conjugated with gelatin were successfully synthesized in aqueous solution of gelatin at room temperature. SEM images showed that when the reaction time reached 2 d, the particles of HgS was formed while the reaction time reached 15 d, the particles turned into the acicular nanoparticles. The average diameter of the acicular nanoparticles was 87 nm with the length of 1.3 μm. The quantum-confined effect of the HgS nanoparticles was confirmed by the ultraviolet-visible and fluorescence spectrum. The results indicate that the change of gelatin conformation not only induce the nucleation, but is favorable to the pattern change of HgS nanoparticles.

Photopolymerization Kinetics of 2-(Acryloyloxy)ethyl Pyrrolidine-1-carboxylate

LI Zhen-feng, NIE Jun

2008, 26(3): 206-210. DOI: 10.7517/j.issn.1674-0475.2008.03.206

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The kinetics of 2-(acryloyloxy)ethyl pyrrolidine-1-carboxylate was studied by real time infrared spectroscopy(RTIR). The influences of light intensity, initiator concentration and different initiators on the kinetics were investigated in this paper. It showed that higher light intensity and initiator concentration had higher curing rate, but the final double bond conversion was almost the same, about 100%. Different kinds of initiator had the same final conversion, but would influence the curing rate.

Effect of Pb²⁺ and Zn²⁺ on the Photographic Properties and Storage Stability of Hydrophilic PTG Materials

LIN Hai-li, CAO Jing, YAO Lin-hui, LI Jin-pei, XIA Pei-jie

2008, 26(3): 211-217. DOI: 10.7517/j.issn.1674-0475.2008.03.211

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The effect of Pb²⁺ and Zn²⁺ on the photographic properties and storage stability of hydrophilic PTG materials using PVA as binder was respectively investigated. The results showed the thermal development fog and relative sensitivity of PTG materials were all significantly decreased by adding Pb²⁺ or Zn²⁺ to the coating dispersions, and those of PTG materials debased more quickly with the increase of percentage of Pb²⁺ or Zn²⁺. In addition, the thermal development fog increased slowly and relative sensitivity increased slightly relative to the primitive PTG materials after the PTG materials including Pb²⁺ or Zn²⁺ aged through different time.

Thiol-Vinyl Silizane Polymerized by UV

SONG Jia-le, CHEN Li-xin, WANG Ya-zhou, WANG Ru-min, ZHANG Jiao-qiang

2008, 26(3): 218-223. DOI: 10.7517/j.issn.1674-0475.2008.03.218

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The UV curing kinetics of thiol-vinyl silizane were investigated by in-situ FT-IR and differential photo-scanning calorimetry. Results indicated that, the polymerization rate at peak maximum is promoted and the final unsaturation conversion is decreased with increasing the functional degrees of thiol group, the polymerization rate of alkyl 3-mercaptopropionate-vinyl silizane is greater than that of alkyl thiol-vinyl silizane. The photo-polymerization characteristic is little sensitive to reacting temperature under lower temperature, the apparent activation energy is 2.3 kJ/mol, but in higher temperature the rate of photo-polymerization deviates from Arrhenius equation.

Preparation and Photoelectric Performance of Flexible Titania Nanotubes Thin Film

ZHANG Feng, TAO Jie, TAO Hai-jun, DONG Xiang

2008, 26(3): 224-232. DOI: 10.7517/j.issn.1674-0475.2008.03.224

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The titania nanotubes were synthesized by hydrothermal process. TiO₂ nanotubes were characterized by means of TEM, XRD and nitrogen adsorption-desorption isotherms. The TiO₂ thin film electrodes were prepared by the titania nanotubes and P25, the surface morphologies, dye loading and photoelectric performance of the film electrodes were analyzed. It is found that the film electrodes are mechanical stable with the addition of the titania nanotubes, The more titania nanotubes film electrodes contain, the higher dye they absorb. When the content of titania nanotubes is 5%, the best photoelectric performance of the film electrodes can be achieved. Its short circuit current of flexible DSSC is 3.25 mA with 1.67% solar-to-electric energy conversion efficiency.

Energy Transfer Between Tb and RE in GdAlO₃:Tb,RE

LUO Lan, CHEN Dong, HUANG Quan

2008, 26(3): 233-237. DOI: 10.7517/j.issn.1674-0475.2008.03.233

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GdAlO₃:Tb,RE phosphor powder was prepared by nitric-citric process. Under UV light excitation(254 nm), it gave green emission(⁵D₄→⁷F₅,544 nm). The green luminescence intensity of GdAlO₃:Tb increased when it was co-doped with Dy, and decreased when co-doped with Ce. Excitation spectra and Energy level sketch indicate that Dy energy level is embedded between Tb ⁵D₄(green emission level) and Tb⁵D₃ (blue emission level), while Ce energy level is embedded above both ⁵D₄ and ⁵D₃. There are the resonant energy transfers between RE ions by the absorbing or emitting phonons, Tb→Dy→Tb energy transfer increases the green emission (⁵D₄→⁷F_J(J=3,4,5,6))and decreases the blue emission(⁵D₃→⁷F_J(J=3,4,5,6)); but Ce→Tb energy transfer increases the blue emission and decreases the green emission.

Study on the Photocatalytic Activity of Rare Earth Gd-doped TiO₂ Nanocrystallites under Simulated Sunlight

CAI He-shan, LIU Guo-guang, LI Xiao-xia

2008, 26(3): 238-243. DOI: 10.7517/j.issn.1674-0475.2008.03.238

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Gd-doped TiO₂ nanocrystallite photocatalysts were prepared by an acid-catalyzed sol-gel method. The photocatalytic decomposition of methyl orange in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities and the TOC removal effect of methyl orange irradiated with a xenon lamp. The prepared samples were characterized by means of the techniques such as XRD, and UV-Vis DRS. The effects of Gd doping on the crystallite sizes, crystal pattern, and optical property of the catalysts were investigated. The results showed that the Gd doping can hinder the transformation from anatase to rutile, decrease the crystallite size of the samples, cause blue-shift of the onset of the absorption spectrum, and enhance the visible light absorption ability of TiO₂, which were responsible for the remarkable increase in photocatalytic decomposition of methyl orange on Gd-doped TiO₂ under simulated sunlight. However, the TOC removal rate was inferior to the apparent decomposition rate of methyl orange on Gd-doped TiO₂.

The Study of Effect of K₄[Ru(CN)₆] Dopant on Photographic Properties and Photoelectronic Lifetime of Silver Iodobromide T-grain Emulsion

WANG Ying-ru, LIU Qing

2008, 26(3): 244-253. DOI: 10.7517/j.issn.1674-0475.2008.03.244

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The effect of K₄[Ru(CN)₆] dopant on the photographic properties and photoelectronic lifetime of the iodobromide T-grain emulsion was studied in this paper. The results showed that the doping amount, position and distribution of the dopant had effected on photographic properties of the emulsion significantly. The relative sensitivities of the emulsions were remarkable increased when the dopant near to the surface and the core of the grain and decreased when the doping region was near the iodide. The preferred doping amount depends on the doping position, and the optimal relative sensitivity was at the position of 66%—92%.The dopant K₄[Ru(CN)₆] can also prolong the decay time of the free electrons and the shallow-trapped electrons, i.e. prolong their lifetime.

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