Measurements of adsorption isotherms of various building and adsorptive materials

It is very important to evaluate the adsorption/desorption properties of building materials with regard to the problem of indoor air pollution. Recently, adsorbent and adsorptive building materials that reduce the concentration of indoor air pollutants have been used in Japan. However, no test method concerning their continuous performance has been examined. Measurement of the adsorption isotherm is an effective means of evaluating the continuous performance because there are many adsorptive materials using physical adsorption (physisorption) and chemical adsorption (chemisorption). In this paper, two methods of adsorption isothermal measurement are examined. The first measuring method involves an adsorption weighing device using a magnetic suspension balance (MSBD method), while the other is the adsorption breakthrough capacity method (ABTC method). The adsorption isotherms of various building materials and their adsorbents are measured using these two methods. Initially, the water vapor adsorption isotherms of each material are measured using the MSBD method. Then, formaldehyde (HCHO) adsorption isotherms are measured using the MSBD and ABTC methods. The measurement of water vapor adsorption isotherms using the MSBD method is particularly straightforward and very useful. Moreover, the ABTC method can easily and quickly measure HCHO adsorption isotherms.