Adsorption equilibrium and dynamics of toluene vapors onto three kinds of silica gels

The benzene is the representative of VOCs and widely exists in the industrial waste gas. In this study, adsorption equilibrium and dynamics of toluene vapors at five initial concentrations (1.39 g·m^-3, 5.12 g·m^-3, 8.38 g·m^-3, 15.6 g·m^-3, 21.3 g·m^-3) onto three kinds of silica gels (GA, GB and GC) were investigated and compared. The experimental results showed that GA has the rich microporous and mesoporous distributions, and the larger surface area and microporous volume than GB and GC. It can be clearly seen that the order of the adsorption rate of adsorbents on the silica gels samples is GA, GB and GC. Due to the suitable pore distribution in the region of micropore and mesopore (1–4 nm), GA exhibits the comparable breakthrough adsorption capacities with GB and GC for a given initial concentration. Moreover, the experimental data were fitted to the Langmuir and Freundlich models, respectively. The Freundlich isotherms correlated with the experimental data presented a better fitting than Langmuir model. Taken together, it is expected that GA silica gel would be a promising adsorbent for the removal of toluene vapors from gas streams. (paper)