Separation in Mass-Exchange Devices with Reactive Membranes

Abstract

Mass transfer rates attainable in membrane separation devices, such as gas permeators or dialyzers, can be limited by solute transport through the membrane. The addition into the membrane of a mobile carrier species, which reacts rapidly and reversibly with the solute of interest, can increase the membrane's solute permeability and selectivity by carrier-facilitated transport. Mass separation is analyzed for the case of fully developed, one-dimensional, laminar flow of a Newtonian fluid in a parallel-plate separation device with reactive membranes. The effect of the diffusion and reaction parameters on the separation is investigated. The advantage of using a carrier--facilitated membrane process is shown to depend on the wall Sherwood number. When the wall Sherwood number is below ten, the presence of a carrier--facilitated membrane system is desirable to improve solute separation.Mass and heat transfer with laminar flow in parallel-plate and cylindrical geometries is a well-known theoretical problem which has been treated by a large number of investigators (1-9). Perhaps the first papers in this area were those by Lévêque (1) and Graetz (2) who studied the heat transfer problem. In the absence of natural convection and for dilute systems, the heat and mass transfer problems are analogous.Parallel plate mass exchange devices with semi-permeable membranes have been studied in a number of separation techniques including hemodialysis, artificial oxygenation, gas separation, and heavy-metal ion separation (10-18). The accurate prediction of solute separation in these mass exchangers is desirable. For parallel-plate geometry, Grimsrud and Babb (5) and Colton et al. (7) developed series solutions to describe the mass transfer process. Kooijman (8) reviewed the analytical and numerical solutions available in the early 1970 f s. Since that time, other

Equilibrium facilitated mass transfer in plate type reactive membrane separation devices

“…The mass transfer rate attainable in membrane separation devices is often limited by solute transport through the membrane. The addition of mobile and reactive carrier species into the membrane, with which the solute reacts reversibly, is of interest because it can give increased mass transfer and high selectivity of the solute [Stroeve and Kim, 1987]. In this technique an organic liquid, immobilized in the pores of a microporous support, can be used to transfer a solute between two aqueous solutions.…”