The GCMC simulations of adsorption of ethanol and water in zeolitic imidazolate frameworks

The adsorption mechanism of ethanol and water in five zeolitic imidazolate frameworks (ZIFs) has been investigated using grand canonical Monte Carlo (GCMC) method. The single adsorption isotherm and the selectivity of mixture adsorption of ethanol and water in ZIFs have been obtained. The results show that, at lower pressures (<10kPa), the adsorption amounts decrease in the order of ZIF-2>-10>-6≈-8≈-4. However, when the pressure is higher than 10kPa, the uptakes order is ZIF-10>-2>-6>-8>-4. And the water uptake decrease with the order of ZIF-10>-2>-4>-6>-8. However, the water uptakes for all the ZIFs is very small. The mixture adsorption of ethanol and water shows that, at a given lower pressure, the selectivity decreases as ZIF-2>-8>-10>-6>-4. However, at a given higher pressure, the selectivity is in the order of ZIF-10>-2≈-6≈8>-4. It can be concluded that ZIF-2 and -10 are suitable for the adsorption and separation of biofuel of ethanol. The total interaction energy distribution of ZIFs with ethanol/water has also been analyzed to interpret the adsorption mechanism of ethanol and water in ZIFs. (paper)