Chinese scientists develop blue LED can detect air pollution

Chinese scientists have recently developed a blue light emitting diode (LED), real-time detection of nitrogen dioxide (nitrogen dioxide, NO2) gas technology. The Harbin Institute of Technology research team said that the low cost and direct technology, can detect the industrial pollution emissions of coal-fired flue gas NO2, and at the same accuracy, are simpler than other detection methods, they have even set up a company to promote the technology.

When Zhiguo Zhang said, NO2 is one of the main exhaust air pollution, because its absorption spectrum is wide, so it is not easy to detect. The previous measurement technology is based on the expensive broadband spectrum xenon arc lamp (xenon arc lamp) as the light source, the use of cheap LED can significantly reduce the cost of monitoring pollution, help to promote technology.

At room temperature and atmospheric pressure, the team's NO2 real-time measurement system can measure the concentration of 3 ppm in just two seconds. The system uses a broadband LED with a power of 100 mW and a wavelength of from 456 to 484 nm as the light source, and uses a lens with a focal length of 100 mm. The light is collimated by a 50 cm long containing NO2 (gas cELl), the gas chamber by a collimating lens to be focused, fed by the monochromator (monochromator) spectrometer with 2048 CCD array detector is composed of computer, then according to the received signal to calculate the concentration of NO2.

Zhang said that the wavelength of about 465 nm LED is the most suitable for the detection of NO2, because the NO2 gas absorption effect of this wavelength is the most significant, and the resolution is high enough to exclude the impact of other gases. The team is currently working on how to measure mercury (mercury), arsenic (arsenic) and other gases, while trying to reduce the cost of the measurement system.

Source: photoelectric News Network