三氯甲烷在金属有机框架膜上的吸附过程监测

Monitor the adsorption process of chloroform over a metal-organic framework film

采用石英晶体微天平（QCM）技术动态监测三氯甲烷在[Cu（C24H22N4O3）]·CH2Cl2金属有机框架膜（Cu—MOFs）上的吸附动力学．吸附与解吸过程中膜质量的变化由QCM的频率变化实时传感测量，结果表明，吸附过程符合假二级动力学模型，其中在三氯甲烷蒸气压条件下的吸附速率常数为在1．01×10^5PaNz存在下速率常数的1．4-2．1倍，半数以上的吸附量相对于气相浓度稀释呈现可逆吸附特征。吸附等温线符合Langmuir等温式，在蒸气压与1．01×10^5PaN2存在条件下（25℃），三氯甲烷在厚度为0．337μm Cu—MOFs上吸附的平衡常数分别为6．47与3．93L／g，最大吸附量分别为27．2与24．7μg／cm^2。

The adsorption kinetics of chloroform over a metal-organic framework film of [Cu（C24H22N4O3）]-CH2C12 （Cu-MOFs） was investigated by a quartz crystal microbalance（QCM） technique. The change in the mass of Cu-MOFs film during the adsorption and desorption processes was monitored in real time by the frequency shift of QCM. The adsorption process follows closely the pseudo-second-order kinetic model. The adsorption rates at vapor pressure of chloroform are 1.4-2.1 times of that in the presence of N2 at atmospheric pressure. More than half of chloroform adsorbed over Cu-MOFs film is reversible with respect to the dilution of chloroform concentration in gas phase. The adsorption isotherms are fitted well by the Langmuir model. For chloroform adsorbed at its vapor pressure and in N2 of 1.01× 105 Pa over Cu-MOFs film with thickness of 0.337 p,m（25 ℃）, the adsorption equilibrium constants are 6.47 and 3.93 L/g, the maximum adsorption capacities are 27.2 and 24.7 μg/cm^2.