Technology for effective removal of hazardous gases using the diffusion scrubber method




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Published on Apr 6, 2010

The Tanaka Laboratory is working to develop practical diffusion scrubbers, which utilize the phenomenon of gas diffusion to collect and measure trace gases in the air.

Q. To separate gases and particles, usually, filters are used. Filters remove particles from the air and then collect gases. But we try to separate the gases and particles at the same time. This is a collection tube for a diffusion scrubber we developed together with a company called Gastec. The white object you can see inside the tube is a porous Teflon tube. It looks as if it doesnt have any holes, but it has microscopic pores, through which gases can pass through the tube.

If the dispersion scrubber method is used, theres no need to pass air through a liquid. The liquid is stored in the tube, and the air flows outside it. Gases in the air pass through the pores of the white tube, in accordance with the principle of diffusion, and are collected in the removal solution inside the tube. Particles pass through the collection tube. Consequently, when air flows, theres no resistance at all. Also, the amount of removal solution is only 1 ml. So the gas concentration in the removal solution becomes extremely high, enabling gases to be measured using simpler analysis methods than before.

Q. For measurement, you just need an air sample, so you only need to collect a small volume of air. But to clean the air in a room, you need to treat a large volume of air. So this kind of collection tube isnt very effective at all. To scale it up, we use cells, with the porous teflon membranes. These look like thin cells, but in between the white porous teflon membranes, you can put the removal solution to collect gases. 102 of the cells are arranged to form slits in this device. When we do this, the gases in air diffuse when air flows through the space between the cells, and they pass through the porous membrane and collect to the removal solution. In this way, its possible to treat a very large volume of air.

Formaldehyde, which is known to cause sick house syndrome, is given off by adhesives, wallpaper, and interior decorating materials. The WHO and Japan have set restrictions on the use of materials that give off more than a standard level of formaldehyde. But at the present time, Taiwan and China have no such standards.

Q. Currently, people talk a lot about developing solar energy or clean energy, and solving environmental problems. But we also need to get rid of the harmful substances in daily life. I think this is already a serious problem in Taiwan and China. Im very pleased when young people working on this problem come here, learn about our technologies, and help to make them widespread.


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