A quartz crystal microbalance study of the adsorption kinetics of 1,2-dichloroethane on metal-organic frameworks [Cu(C24H22N4O3)]·CH2Cl2 film

In this work, the adsorption kinetics of 1,2-dichloroethane (DCE) on [Cu(C24H22N4O3)]·CH2Cl2 metal-organic framework (Cu-MOF) film were monitored in real time by a quartz crystal microbalance technique. It is shown that the adsorption process follows closely the pseudo-second-order kinetic model. With increasing amount of DCE added, the adsorption rate constant decreases while the initial adsorption rate increases. More than half of DCE adsorbed on Cu-MOF film is reversible with respect to the concentration dilution in gas phase. The adsorption isotherms are fitted well by the Langmuir model. The pre-adsorbed N2 at atmospheric pressure on Cu-MOF film reduces slightly the adsorption rate constant, equilibrium constant and capacity of DCE. The adsorption rates at vapor pressure of DCE are 1.2-1.8 times of those in the presence of N2 at atmospheric pressure. With increasing film thickness, the adsorption rate constant and mass adsorbed per unit film mass decreased. For DCE adsorbed at its vapor pressure (25 °C) on Cu-MOF film with thickness of 0.251, 0.589 and 1.19 μm, the adsorption equilibrium constants are 716.5, 695.5 and 649.2 L/mol, and the saturation adsorption capacities are 6.537, 5.742 and 5.193 mmol/g, respectively. With increasing temperature, the adsorption rate constant increases, but the mass of DCE adsorbed on the adsorption equilibrium constant and capacity decreases.