Adsorption of chlorinated volatile organic compounds on MCM-48

Adsorption equilibria of seven chlorinated volatile organic compounds on mesoporous silicate MCM-48 were obtained using a gravimetric technique. For comparison purposes, three organic sorbents (activated carbon, activated carbon fiber and nonionic polymer resin, SP850) and three inorganic sorbernts (DAY zeolite, mesoporous silicate MCM-41, and chromium-impregnated MCM-48) were used to investigate adsorption characteristics of trichloroethene chosen as a model compound of chlorinated volatile organic compounds. Mesoporous MCM-48 has a narrow pore size distribution, and capillary condensation of chlorinated volatile organic compounds can be observed at P/P-0 = 0.2 to 0.3. A new hybrid isotherm model for mesoporous sorbents is proposed by combination of the Langmuir isotherm at low pressure and the Sips isotherm in the multilayer region. Moreover, the surface heterogeneity of MCM-48 was evaluated in terms of an isosteric enthalpy of adsorption calculated using the proposed isotherm model.