Liquid Membrane Separation Process

Rautenbach R and Machhammer O. Modeling of liquid membrane separation processes. J Membr Sci 1988 36 425-444. 

Liquid membrane separation processes have received considerable attention because of their potential advantages over other separation processes, both conventional (distillation, solvent extraction) and newly developed (sohd membranes). 

Liquid membrane separation processes are widely used in biochemical processing, in industrial wastewater treatment, in gas separations, in food and beverage production, and in pharmaceutical apphcations. Below the reader can find some fields where research, development and scale-up efforts are expected ... 

However, in spite of the known advantages and applications of liquid membrane separation processes in hollow-fiber contactors, there are scarce examples of industrial application. The industrial application of a new technology requires a reliable mathematical model and parameters that serve for design, cost estimation, and optimization purposes allowing to accurate process scale-up. " The mathematical modeling of liquid membrane separation processes in HFC is divided into two steps (1) the description of the diffusive mass transport rate and (2) the development of the solute mass balances to the flowing phases. 

In conclusion, the mathematical description of the overall diffusive flux in liquid-membrane separation processes needs the calculation of the corresponding mass transport parameters (kt, k 11.. AC kL A) and equilibrium param-... 

The design and scale-up of liquid-membrane separation processes need separation and concentration mathematical models as reported in Section 29.2.1. When complex solutions such as wastewaters are treated, several simplifications according to the specific characteristics of the system are usually assumed in order to reduce the number of parameters and mathematical complexity of the EPT model. From a kinetic point of view, the transport through the membrane... 

Bringas, E., San Roman, M.F., Irabien, J.A., and Ortiz, I. 2009. An overview of the mathematical modeling of liquid membrane separation processes in hollow fibre contactors. J. Chem. Technol. Biotechnol. 84 1583-1614. 

The simple rate equations for the various liquid-membrane separation processes in use prior to 1978 were reviewed previously. Since that time, much has been done to improve them, especially by considering the influence of the intemal microdroplets and the effects of leakage of the intemal reagent which was previously ignored.Cahn et al., studying copper extraction, have taken membrane instability into account by modifying the basic permeation rate equation to include a leakage term. This modified equation has the form... 

Multiple emulsions are the basis of so-called liquid membrane separation processes, where one solute is prefermtially transferred from, say, the outer to the inner aqueous phase of a water-in-oil-in-watCT emulsion. The preferred solute is transferred faster because it is more soluble in the oil phase than other species dissolved in the inner aqueous phase. Transport across the oil phase may occur by diffusion of solute molecules or solute-containing reverse micelles or microemulsion drops. Sometimes a carrier is added to the oil to increase solute solubility in the oil by formation of a solute/carrier complex. 

Facilitated mass transfer Similarly to LLE, the selectivity and efficiency of the liquid membrane separation process can be considerably improved if a suitable extractant with a high selectivity for the analyte of interest is used. This extractant, often referred to as the carrier, facilitates the mass transfer of the analyte between the feed and receiver solutions. The liquid membrane phase in this case usually consists of a suitable liquid extractant or an extractant dissolved in an organic solvent (diluent). The extractant facilitates the transport of the analyte from the feed phase to the liquid membrane phase by chemically interacting with it. This interaction leads to the selective extraction of the analyte into the... 

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