Vapor transport in graphene oxide laminates and their application in pervaporation

A Review on the Morphology and Material Properties of the Gas Separation Membrane: Molecular Simulation

Gas membrane separation technology is widely applied in different industry processes because of its advantages relating to separation performance and economic efficiency. It is usually difficult and time consuming to determine the suitable membrane materials for specific industrial separation processes through traditional experimental research methods. Molecular simulation is widely used to investigate the microscopic morphology and macroscopic properties of materials, and it guides the improvement of membrane materials. This paper comprehensively reviews the molecular-level exploration of the dominant mechanism and influencing factors of gas membrane-based separation. The thermodynamics and kinetics of polymer membrane synthesis, the molecular interactions among the penetrated gases, the relationships between the membrane properties and the transport characteristics of different gases in the composite membrane are summarized and discussed. The limitations and perspectives of the molecular simulation method in the study of the gas membrane separation process are also presented to rationalize its potential and innovative applications. This review provides a more comprehensive reference for promoting the materials' design and engineering application of the gas separation membrane.

Double-Crosslinked GO Interlayer Framework as a Pervaporation Hybrid Membrane with High Performance

Graphene oxide (GO), as a two-dimensional structure material, has attracted widespread attention in the field of molecule sieving. However, GO-based membranes usually exhibit undesirable separation performance because the microstructure of GO is difficult to adjust. Herein, a novel double-crosslinking strategy for tuning the interlayer spacing of GO is reported. The hybrid membrane fabricated by the double-crosslinking strategy was used for pervaporation (PV) dehydration of isopropanol. To achieve high-performance of the PV hybrid membranes, the effects of operating cycles, chitosan concentration, and GO concentration were systematically investigated. The PV hybrid membranes were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurement, and scanning electron microscopy. The results demonstrate that the interlayer of GO can be adjusted successfully by the double-crosslinking strategy. The fabricated hybrid membrane containing 0.1 wt % GO exhibited excellent performance with a flux of 4391 g/m2h and a separation factor of 1491, which indicated that the double-crosslinking strategy may extend the applications of GO in the field of membrane separation.

Membrane Technology in Catalytic Carbonylation Reactions

In this review, the recent achievements on the use of membrane technologies in catalytic carbonylation reactions are described. The review starts with a general introduction on the use and function of membranes in assisting catalytic chemical reactions with a particular emphasis on the most widespread applications including esterification, oxidation and hydrogenation reactions. An independent paragraph will be then devoted to the state of the art of membranes in carbonylation reactions for the synthesis of dimethyl carbonate (DMC). Finally, the application of a specific membrane process, such as pervaporation, for the separation/purification of products deriving from carbonylation reactions will be presented.

Review: Membrane Materials for the Removal of Water from Industrial Solvents by Pervaporation and Vapor Permeation

Organic solvents are widely used in a variety of industrial sectors. Reclaiming and reusing the solvents may be the most economically and environmentally beneficial option for managing spent solvents. Purifying the solvents to meet reuse specifications can be challenging. For hydrophilic solvents, water must be removed prior to reuse, yet many hydrophilic solvents form hard-to-separate azeotropic mixtures with water. Such mixtures make separation processes energy intensive and cause economic challenges. The membrane processes pervaporation (PV) and vapor permeation (VP) can be less energy intensive than distillation-based processes and have proven to be very effective in removing water from azeotropic mixtures. In PV/VP, separation is based on the solution-diffusion interaction between the dense permselective layer of the membrane and the solvent/water mixture. This review provides a state-of-the-science analysis of materials used as the selective layer(s) of PV/VP membranes in removing water from organic solvents. A variety of membrane materials, such as polymeric, inorganic, mixed matrix, and hybrid, have been reported in the literature. A small subset of these are commercially available and highlighted here: poly(vinyl alcohol), polyimides, amorphous perfluoro polymers, NaA zeolites, chabazite zeolites, T-type zeolites, and hybrid silicas. The typical performance characteristics and operating limits of these membranes are discussed. Solvents targeted by the U.S. Environmental Protection Agency for reclamation are emphasized and ten common solvents are chosen for analysis: acetonitrile, 1-butanol, N,N-dimethyl formamide, ethanol, methanol, methyl isobutyl ketone, methyl tert-butyl ether, tetrahydrofuran, acetone, and 2-propanol.