| Advanced Oxidation Techniques Jensen Technologies has expertise in the following oxidation techniques:
The Photocatalytic Organic Oxidation system destroys in a simple, easy to use, and efficient continuous mode operation. It is designed for large, hard to dispose of quantities aqueous organic compounds. The systems main use is the pretreatment of waste water. .It is used in series with the HW Process Technologies’ EMS Process. PRINCIPLE One solution to this problem is a Photo-catalyst. What is a Photo-catalyst? Photo-catalyst produces surface oxidation to eliminate harmful substances such as organic compounds and/or nearby bacteria, when it is exposed to the sun or a fluorescent lamp. By applying this principle to water treatment, photo-catalyst can be used for various steps in purifying a contaminated environment. The function of the photo-catalyst can be divided into major categories as follows:
Preventing contamination Anti-bacteria It might be well understood that the functions listed above are those which amplify or accelerate the functions of the sun, or ultra-violet radiation. In this sense, it is not strange to regard titanium dioxide as a photo-catalyst from the viewpoint that it works as the catalyst in accelerating the functions of the light. What kind of light is necessary for the photo-catalyst? As we explained, the photo-catalyst can be activated by light, so what kind of light is necessary for the photo-catalyst? There are various sources of light such as the sun, incandescent lamps, fluorescent lamps, light traps, disinfectant light, and so on. Those sources emit lights with different wavelengths necessary for their specific purposes. TiO2 is a semiconductor which turns to a high-energy state by receiving light energy, and releases electrons from its illuminated surface. If the energy received at this stage is high enough, electrons that were initially located in the so-called `valence band' all jump up to the `conduction band'. Thus, the energy that makes electrons jump up is provided by light, and this light energy is believed to be the energy of the light's wavelengths. Therefore, calculating from the height that the electrons have to jump up, this light should have the same wavelength as ultraviolet light. E = hv E : energy h : Plank's constant v : frequency v = c /A c : light speed A : wavelength Therefore, E = hc /λ Here, E is titanium dioxide 3.2 eV (3.2 eV = 3.2 × 1.6 × 10-19J), and if you substitute the determinate values （c: 3.0 × 108m/s, h: 6.63 × 10-34J・s）, you will find out that the necessary wavelength is approx. 380 nm, which tells us that the light needed to activate Photocatalyst is ultraviolet light. Thin-film Photocatalyst Titanium dioxide (TiO2) is a harmless substance widely applied in various fields such as cosmetics, toothpaste, extenders for medicines, and coating. For these uses, TiO2 is usually supplied in the form of powder. But in order to use TiO2 as an effective photo-catalyst for the 5 functions, powder is not an appropriate form, for it may be blown off by wind or washed out by water, and when used to purify water, it has to be separated from the water. Thus, a method to fix the powder has long been considered. It is easy to fix powdery TiO2 with a binder, but if an organic binder is used, the photo-catalytic reaction will destroy the binder itself. Inorganic binder is not influenced by photo-catalytic reaction, but only the powder exposed on the surface can work effectively despite the total amount of powder contained in the binder. In collaboration with National Industrial Research Institute of Nagoya, The Japanese succeeded in developing the coating technology of photo-catalytic thin-film that can cover all surface only with TiO2, instead of using powdery TiO2. This method, called the Sol-Gel method, uses titanium alkoxide as a starting material. It is hydrolyzed to obtain sol, and the sol is applied to coat substrate through such coating methods as the dip-coating method, to form a film. At this stage, the film is not the film of TiO2. So, the sol is sintered along with the substrate to be crystallized, and thus the film of titanium dioxide is formed. J-tech has a bench unit for testing and developing a large scale prototype. back to Services |
