The gas-photocatalytic degradation of trichloroethylene without water

The photocatalytic degradation of gaseous trichloroethylene (TCE) without water has been studied. The degradation products were determined to be CO₂, HCl and Cl₂, and the reaction stoichiometry, was described as

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. The degradation rate was found to be linear with 0.16 power of the illumination intensity. When the TCE concentration was low (10¹⁴ mol L⁻¹ or a little more), its degradation rate model could be considered as first order kinetics. A mechanism of valence band hole oxidation was proposed.     

Photocatalytic activity of ZnO films with micro-grid structure

A layer of zinc oxide (ZnO) micro-grid was deposited on the surface of ZnO film using the DC reactive magnetron sputtering method and the micro-sphere lithography technique on glass substrates. Samples of this layer were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and ultraviolet-visible light spectroscopy. X-ray diffraction showed the high crystallinity of ZnO film and the regular arrangement of the micro-grid. The microgrid ZnO has a lower specular reflection and a higher diffuse reflection, allowing incident light to reflect two or three times to enhance the usage of light. Photocatalytic degradation experiments on methylene blue using both ZnO micro-grid and ordinary film showed that the ZnO micro-grid has better photo-catalytic properties than ordinary film. The ZnO micro-grid enhanced the photocatalytic efficiency of ZnO film by 28% with a degradation time of 300 min.     

光催化氧化法处理垃圾填埋场渗滤液的研究

研究了紫外光催化氧化法对垃圾填埋场滤渗液的降解机理,根据废水质的不同,考察了TiO2催化剂用量,pH值,通气量,反应时间,光照强度等因素对放心水中有机污染物和色度去除的最佳条件,用现场采集的渗滤液原水和氧化沟出水试验,CODcr去除率分别达到80．6％,77．3％,色度去除率分别为87．9％,83．3％。     

日光下黄砂负载TiO2降解邻氯苯酚水溶液

研究了以黄砂为载体,ＴｉＯ２为催化剂,以太阳光为光源对邻氯苯酚水溶液进行光催化降解的可行性。结果表明,锐钛型ＴｉＯ２邓邻氯苯酚有显著的光催化降解作用;ＴｉＯ２的催化活性在焙烧温度３００℃时最高。     

Photocatalytic oxidation of the textile dye basic red 18 with irradiated titanium dioxide

One of the major problems of textile wastewater is the presence of dye materials, because colour is visible to the public even if the dye concentration is lower than other pollutants, and needs therefore to be removed from the wastewater before it is discharged. Techniques based on “advanced oxidative processes” such as photocatalysed oxidation seem to be very promising for industrial wastewater treatment, especially for decolourization of textile effluents. In this work, we describe the photocatalytic degradation of the textile dye Basic Red 18 (BR 18) in aqueous solution using two different types of TiO₂ as photocatalyst: Degussa P25 (80% anatase) and Framitalia (100% anatase). Photooxidation of BR 18 was followed by HPLC analysis, and kinetic parameters were evaluated in order to optimise the treatment procedure. The results obtained in this work showed that the colour became virtually zero and the chemical oxygen demand (COD) is strongly reduced at the end of the treatment. The obtained results are compared with the efficiency of decolourization using the H₂O₂/UV System. Finally, marine mussel test was used to evaluate the efficiency of photocatalytic oxidation with TiO₂ in terms of ecotoxicity. A significant reduction of cumulative mortality was observed for the treated effluent.     

Treatment of textile dye wastewater using ozone combined with photocatalyst

Ozonolysis combined with photocatalysis was used as a new approach for the treatment of textile dye wastewater containing azo dyes. The color reduction was very fast when only ozone was used for the treatment, but a 90% Total Organic Carbon (TOC) reduction was obtained only during a combined treatment. Reactive Black 5 dye containing two different percentages of NaCl was used for the experiment. The color reduction was fast in the neutral and basic pH. However for a fast TOC reduction acidic pH was found to be more effective. On‐line UV‐Vis spectrophotometry was used to measure the color reduction.     

Preparation and photocatalytic performance study of dual Z-scheme Bi2Zr2O7/g-C3N4/Ag3PO4 for removal of antibiotics by visible-light

At present, the high re-combination rate of photogenerated carriers and the low redox capability of the photocatalyst are two factors that severely limit the improvement of photocatalytic performance. Herein, a dual Z-scheme photocatalyst bismuthzirconate/graphitic carbon nitride/silver phosphate (Bi₂Zr₂O₇/g-C₃N₄/Ag₃PO₄ (BCA)) was synthesized using a co-precipitation method, and a dual Z-scheme heterojunction photocatalytic system was established to decrease the high re-combination rate of photogenerated carriers and consequently improve the photocatalytic performance. The re-combination of electron-hole pairs (e⁻ and h⁺) in the valence band (VB) of g-C₃N₄ increases the redox potential of e⁻ and h⁺, leading to significant improvements in the redox capability of the photocatalyst and the efficiency of e⁻-h⁺ separation. As a photosensitizer, Ag₃PO₄ can enhance the visible light absorption capacity of the photocatalyst. The prepared photocatalyst showed strong stability, which was attributed to the efficient suppression of photo-corrosion of Ag₃PO₄ by transferring the e⁻ to the VB of g-C₃N₄. Tetracycline was degraded efficiently by BCA-10% (the BCA with 10 wt.% of AgPO₄) under visible light, and the degradation efficiency was up to 86.2%. This study experimentally suggested that the BCA photocatalyst has broad application prospects in removing antibiotic pollution.     

Removal of humic acid using TiO2 photocatalytic process--fractionation and molecular weight characterisation studies

The photocatalytic removal of humic acid (HA) using TiO₂ under UVA irradiation was examined by monitoring changes in the UV₂₅₄ absorbance, dissolved organic carbon (DOC) concentration, apparent molecular weight distribution, and trihalomethane formation potentials (THMFPs) over treatment time. A resin fractionation technique in which the samples were fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids, hydrophilic charged (CHA) and hydrophilic neutral (NEU) was also employed to elucidate the changes in the chemical nature of the HA components during treatment. The UVA/TiO₂ process was found to be effective in removing more than 80% DOC and 90% UV₂₅₄ absorbance. The THMFPs of samples were decreased to below 20 μg l⁻¹ after treatments, which demonstrate the potential to meet increasingly stringent regulatory level of trihalomethanes in water. Resin fractionation analysis showed that the VHA fraction was decreased considerably as a result of photocatalytic treatments, forming CHA intermediates which were further degraded with increased irradiation time. The NEU fraction, which comprised of non-UV-absorbing low molecular weight compounds, was found to be the most persistent component.     

Immobilization of self-assembled pre-dispersed nano-TiO2 onto montmorillonite and its photocatalytic activity

The immobilization of pre-dispersed Ti O_2 colloids onto the external surface of the clay mineral montmorillonite(Mt) was accomplished and regulated via a self-assembly method employing the cationic surfactant cetyltrimethylammonium bromide(CTAB). The role of CTAB in the synthesis process was investigated by preparing a series of Ti O_2-CTAB-Mt composites(TCM) with various CTAB doses. The results indicated that a uniform and continuous Ti O_2 film was deposited on the external surface of montmorillonite in the composite synthesized with 0.1 wt.% of CTAB, and the TCM nano-composites showed much higher values for specific surface area, average pore size and pore volume than the raw montmorillonite clay. Then, the formed TCM materials were applied in photocatalytic degradation of 2,4-dichlorophenol(2,4-DCP) in aqueous solution. The degradation efficiency reached as high as 94.7%. Based on the degradation intermediates benezoquinone, fumaric acid and oxalic acid identified by LC–MS analysis, a mechanism for the photocatalytic oxidation of 2,4-DCP on Ti O_2/Mt nano-composites is proposed.     

活性炭负载TiO2催化剂对直接耐酸大红4BS溶液的光催化降解研究

采用溶胶-凝胶法制备了活性炭负载型TiO2催化剂,采用了XRD、BET和SEM对催化剂进行表征。研究了催化剂对直接耐酸大红4BS的紫外光催化降解,比较了活性炭、P25和TiO2／AC对4BS溶液的降解能力,探讨了催化剂煅烧温度和投加量以及染料溶液的初始浓度对光催化降解率的影响,并对催化剂进行了回收再生实验。结果表明,500℃下煅烧的TiO2／AC催化剂比表面积为1147．88m^2／g、TiO2粒径为21．9nm、晶相组成以锐钛矿为主,具有良好的光催化活性和稳定性;90min后2g／L催化剂对150mg／L的4BS溶液紫外光催化降解率达到99．8％。