Study On Mechanism Of Formaldehyde Purification From Indoor Air By Potted Plants

Formaldehyde, one of main indoor air pollutants, has become the obligatory measured target in indoor air quality test as its high toxicity, wide variety of sources, last long time and serious threat to human health. Compared with other methods, plant purification is an ideal method of controlling formaldehyde in indoor air pollution because it is economic, easy operating, no secondary pollution, and potted plants can also beautify the environment and use in large area. This thesis mainly discussed the significance and status of potted plant purification of formaldehyde in indoor air at home and abroad. A dynamic chamber technique was employed to investigate the effect of formaldehyde concentration and light intensity on formaldehyde purification by spider, golden pothos and aloe. The effect of flow rate on formaldehyde purification by potted spider plant was studied. Also we analyzed the contributions of the three plant leaves and soil to formaldehyde purification.The results showed that the three potted plants all have long-term function on formaldehyde purification, and the purification rate in the day was higher than in the night. At the flow rate of 200L/h with the light intensity of 12000Lx, the formaldehyde purification rates of potted spider plant, golden pothos and aloe were 0.24-1.88 mg/h,0.23-1.07 mg/h and 0.21-0.79 mg/h in the day, and 0.06-1.29 mg/h,0.10-0.63 mg/h and 0.11-0.28 mg/h in the night, respectively. The formaldehyde purification rate was accelerated by increasing the inlet concentration of formaldehyde. Changes of light intensity in 4000-12000Lx range had no significant effect on formaldehyde purification rate by potted spider plant. However, the formaldehyde purification rates were accelerated with the increase of light intensity for golden pothos and aloe. The study showed that soil (including underground potted plant) contribution to formaldehyde purification was higher compared with aboveground potted plant. The purification rates of potted spider plant, golden pothos and aloe were 0.94-7.43μg/(g-h),0.23-0.87μg·h) and 0.31-1.29μg/(g·h) in the day, and 0.15-3.4μg/(g·h),0.13-0.40μg/(g·h) and 0.17-0.44μg/(g·h) mg/h in the night, respectively.The results showed that the orders for tolerance levels of formaldehyde and the purification rate were:spider plant> aloe> golden pothos. The purification rate of spider plant based on unit mass was higher than those of aloe and gold pothos while there was no significant difference between the purification rates of aloe and golden pothos. Therefore we conclude that the best plant for indoor formaldehyde purification is potted spider plant among the three species.