A new insight into adsorption state and mechanism of adsorbates in porous materials

An in situ freeze method (in liquid N-2) is developed to study the adsorption behaviours of volatile organic compounds (VOCs). Using the proposed method, the adsorption state and adsorption mechanism of adsorbates (pore filling effect or mono/multilayer stacking) in pores of adsorbent can be perceived clearly. We can also acquire the contribution rate of each pore to adsorption capacity. It is found that for toluene adsorption, more pores smaller than around 1.1 nm should be made in activated carbon if it's below 100 ppm, while more pores of around 1.2-5 nm should be made if it's beyond 1000 ppm. This measurement method presents a more comprehensive description on the adsorption state of VOCs in micro- and mesopores, extending the development of adsorbent design and adsorption mechanism in chemical and environmental engineering.