注册日期: Nov 2001
来　　自: 血盆大口
发贴数量: 825

有化学基础的英语强人进来！紧急

实在没办法了，时间非常紧急，麻烦大家翻译一下，不要网站的那种所谓的翻译。
In recent years,the heteogeneous photocatalysis for total oxidation of organic and inorganic water pollutants has been studied extensively. Such reactions has usually been carried out by using suspensions of powered TiO2. However, the filtration of the slurries is very difficult for great quantities. Recently,a few studies have concerned the perparation of photocatalyst immobilization on different supports (for example, glass plate or glass fiber).The most used and efficient technique to immobilizing the catalyst on the support.
In this paper, we present two sol-gel methods for perparing TiO2 particles,one using alcohol and the other without alcohol. For each method , the temperature and the duration of the technical treatment were studied.WE carried out the influence of the two paramenters on the specific surface,the ctystallinity, and photocatalytic activity of the semi-conductor.
For the method without alcohol (WOA1),the colloidal solution was perpared according to the method from Torimo et al.A 7.4cm3 of titanium tetraisopropoxide was added,drop by drop,to 30 ml of 1 M HNO3 aqueous solution, and then agitated for 2 h to give a transparent TiO2 sol,in which 2.0g TiO2 are contained to PH 3,with the addition of 1 M NAOH solution after dilution of the colloid with 100ml water,resulting in a turbid TiO2 colloid.The suspension was agitated for 2 h at room temperature, and centrifuged ,and then washed with disitilled water. The isolated TiO2 was dried for 1 h at 100oC in air. The resulting solid was calcinated in air at different temperatures and times (see table I).For the method with alcohol (WA l), a 0.1 mol l-1 titanium tetraisopropoxide solution in asopropyl alcohol was perpared and added with water (n water / alcohol =100).The suspension was agitated for 1 h at room temperature and centrifuged. The end of the procedure was the same as the first method.
The photocatalytic activity of these compounds was tested by using the benzamide degradation. This aromatic amide was chosen as a model compound because it is a representative water organic pollutant. Experiments were carried out in a Pyrex photochemical reactor with a 450 W mediumpressure mercury lamp (HANOVIA PC 451-050,the arc length is 4.8cm). Running water is passed through the timble to cool the reaction solution and to remove the UV fraction of the light ,as well as any irradiation below 290 nm .The degradation of benzamide was followed by HPLC after injection of 20 ul of the irradiated sample (previously filtered)in the chromatograph.All experimental conditios used were the following:C18 column;eluent, acetonitrile/water (10:90 v/v); flow rate, 1 ml min-1; detector wavelength,224nm.The specific surfaces of the samples were determined by N2 BET absorption analysis.The crystalline phase was determined by the X-ray diffraction method (XRD). The results of all the experiments were collected in Table I.
The initial sol-gel layers (dried 1 h at 100oC)present a large N2 BET-specific surface (162 m2 g-1) for WOAl and 300 m2 g-1 for Wal). These specific surfaces decrease rapidly(respectively,until 40 and 26m2 g-1 ) when the thermal treatment duration increases. This is in accordance with the results of Zaharescu et al. The crystallinity of the perpared-TiO2 depends a lot on the temperature and the time of the initial sol-gel layer treatment.For obtaining good-quality TiO2 crystals,500oC is needed with a time treatment superior to 10 h and with the WAl method (FIG.1)
In FIG.2,we notice more efficiency from the WAl method than from the WOAl one . With a sample obtained through the sol-gel plus alcohol method,treated during 10 h at 500oC ,we can degrade in the whole benzamide solution less than 2 h,while a sample obtained with the other method and treated in same conditions only give a 30% amide degradation.In this case,the photocatalyst’s specific surface does not intervene because there is a low variation between the samples treated at 500oC (see Table I).The most important factor is the crystallinity of the catalysts.The most efficient samples are the best crystallized(FIG.1)
The continuation of our work consists now of immobilizing the catalyst on the glass fiber. The supported catalyst will be then tested on the semipilot plant pf the plataforma solar de almeria in Spain with the financial support of European Community(TMR Program).

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于是我就掐住他的脖子，用力抻出他的血管，围着脖子绕三圈，然后用力一吸…………
血液总是最美味的。

-----吸血狼

There are a lot of people totally opposed to VIOLENCE. They’re all dead.

理性的四环胜过激情的平安大道

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