(376ah) Molecular Simulation Study of Polymers of Intrinsic Microporosity Nanofilms for Organic Solvent Nanofiltration
Chemical separations account for 40-70% of capital and operating costs in chemical production. Existing separation technologies such as distillation are energy-intensive. As an alternative, membrane separation has been proven to be more energy-efficient and easier to operate. While membrane filtration in aqueous systems is well-established, its application in organic media has been on the rise recently. In particular, organic solvent nanofiltration (OSN) shows great potential for the molecular separation of high value solutes from organic solvents. Microporous polymer membranes are drawing considerable attention owing to their ease of processing and capability for molecular discrimination. From a molecular perspective, the study aims to explore the performance of polymers of intrinsic microporosity (PIM-1) nanofilms for OSN applications. Molecular simulations are performed for the permeation through PIM-1 nanofilms by a series of organic solvents such as acetone, acetonitrile, ethanol and methanol. Solvent permeabilities obtained are in good agreement with experimental data, thereby validating the simulation results. The permeabilities are found to correlate well with combined solvent property and comparable to those of existing polyamide nanofilms. Subsequently, molecular simulations of OSN on the rejections of hesperetin solute from organic solvents are investigated. While the solute rejection is 100%, the solvent fluxes and permeabilities decrease. For all solvents, the adsorption of hesperetin on PIM-1 is unraveled to be solute rejection mechanism. In the case of acetone, solvent permeability is the highest due to high polymer swelling and hesperetin solubility. Further detailed analyses of the molecular simulations provide the underlying insights on the separation performance. Therefore, this simulation study illustrates the performance of PIM-1 nanofilms for OSN based on the manifestation of molecular interactions among solute, solvent and membrane.