The absorption of air pollutants by herbs and their association with photochemical reaction
Date Issued
2011
Date
2011
Author(s)
Jhang, Yuan
Abstract
The aim of this research is to investigate the ability of common herbs to purify four kinds of air pollutants, to study the effects of magnetic field direction on the capacity of herbs to purify air pollutants, and to explore the correlation between essential oils volatilized by herbs and ozone which is the main product of photochemical reaction.
Herbs plants were bought from the flower market, acclimatized for a period of time, and used for uptake measurements. A transparent fumigation chamber with size of 21L, is designed to measure the uptake rate of these herbs against 100ppb ozone, 300ppm acetone, 30ppm toluene, and 30ppm ammonia. Results showed that Blue Boy rosemary has the greatest deposition velocity for absorbing ozone, acetone and toluene, Giant Lavender is also good at absorbing the pollution of toluene, and stevia has the best ability to absorb ammonia. However stevia is highly sensitive to ammonia. It will suffer and show injury symptoms, making it difficult to uptake ammonia for a long time. After a collective screening and comparison, Blue Boy rosemary, stevia, and Rose geranium are recommended as an adequate plant set for uptaking all four toxic gases in office and house.
Round magnet with diameter of 1.2 cm, and magnetic field of 1000mT, were used for studying the effects of magnetic field direction on the capacity of herbs to purify four kinds of air pollutants. The transparent fumigation chamber is also used to measure the uptake rate of ozone at 100ppb, acetone at 300ppm, toluene at 30ppm, and ammonia at 30ppm, respectively. Results showed that generally the magnetic field direction can not significantly affect the capacity of herbs to purify four kinds of air pollutants. Only stevia showed higher uptake to ammonia at negative magnetic field and non magnetic field.
A transparent smog chamber with size of 90 x 90 x 180Cm was designed and setup for studying the photochemical reaction related with herb essential oils. Out of seven herb species, five herbs simply play the role as air-cleaner as they can absorb ozone and nitrogen dioxide constantly in the smog chamber. However, when Blue Boy rosemary and Rose geranium were beaten for 50 times by hand to make the essential oil release, the ozone concentration bump up dramatically in the chamber. The reason is still unknown and need more investigation in the future.
As different plants exhibited different capability to purify different air pollutants, we recommend people to choose the appropriate herbs at different location, so that they can clean the air more efficiently. Since stevia showed a high degree of sensitivity to ammonia, it probably can be used as an indicator plant for ammonia pollution. When the herbs were proven to induced photochemical reaction and raise the ozone concentration, we may expect to partially harm the herbs, so that the ozone concentration is only beneficial for disinfecting. Then the herbs can play both the roles of air cleaner and disinfectant in indoor areas.
Subjects
Herbs
ozone
acetone
toluene
ammonia
magnetic field
essential oil
photochemical pollution
Type
thesis
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