Study On The Separation Process And The Transport Mechanism Of Pervaporation In Isopropanol/Water

The separation process of isopropanol/water by pervaporation (PV) using PVA-PAN composite membrane was studied in the thesis.The swelling experimental results showed that PVA homogeneous membrane was high hydrophilic, in which water was preferentially soluted. So PVA homogeneous membrane can be used to the separation of aqueous isopropanol as a kind of preferentially non-watertight PV membrane. The interactional parameter between water and membrane and that between isopropanol and membrane were 0.744 and 1.671 respectively. Interactional parameters between water and isopropanol increased with the rising of the mass fraction of isopropanol.The effects of feed temperature, isopropanol mass fraction, and downstream pressure on the performances of the PV membrane were discussed. The results showed that the PV performance of PVA-PAN composite membrane was good for the separation of isopropanol/water under high mass fraction of isopropanol. The pervaporation apparent activity energy (Ea) of isopropanol and that of water were respectively 43.21 X 10³Â·mo^-1 and 17.36×10³J·mol^-1. The total Ea of PV separation of isopropanol/water increased with the decrease of the mass fraction of isopropanol. Separation factor and permeate separation index (PSI) of the PVA-PAN composite membrane could approach 2000 and 0.8×10³ kg·m^-2·h^-1.According to solution-diffusion model and Fick's law, the permeate flux equation of isopropanol and that of water at 323K were obtained. Theoretical predictions agreed well with the experimental results.