Removing characteristic of indoor air pollutants according to activated carbon pot and plant using a tin oxide gas sensor

Abstract

Activated carbon has a high porous structure and it can absorb many kinds of chemical substances in an atmosphere. In this study, the capability was examined for formaldehyde, toluene and xylene using a tin oxide gas sensor, which are named as VOCs(volatile organic compounds). An interior plant pot was made of the activated carbon and was adopted as a subject. It had a high capability to remove those chemicals. The pot, which was installed in an experimental chamber, could absorb entirely the formaldehyde of about 6.5 ppm in five hours. It also had a removing capability to larger molecular weight chemicals, for example toluene and xylene. The sensor has higher sensitivity to the gases because there are a lot of free radicals on the sensor surface and many free electrons generate in the sensor bulk. Based on these results, the three pots were installed in a real office room and examined the removing capability. In the room, the formaldehyde was emitted continuously and the saturated concentration was almost constant. The concentration was decreased until 60% by installing the pots. They had a high removing capability to continuously emitting formaldehyde. The sensor output was sometimes calibrated by a formaldehyde measuring instrument. In the experimental room, temperature, humidity, light intensity, oxygen and carbon dioxide concentrations were also measured simultaneously. The characteristics had a correlation each other.