Membrane Flash Index: Powerful and Perspicuous Help for Efficient Separation System Design.

Andras Jozsef Toth,Bela Viskolcz,Asmaa Khaled Mohamed Selim,Daniel Fozer,Milán Szőri,Eniko Haaz,Peter Mizsey,Botond Szilagyi

doi:10.1021/acsomega.0c01063

Andras Jozsef Toth, Bela Viskolcz + Show 6 more

Open Access

https://doi.org/10.1021/acsomega.0c01063

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Abstract

There are different factors and indices to characterize the performance of a pervaporation membrane, but none of them gives information about their capabilities in the area of liquid separation compared to the most convenient alternative, which is distillation. Membrane flash index (MFLI) can be considered the first and only one that shows if the membrane is more efficient or not than distillation and quantifies this feature too. Therefore, the MFLI helps select the best separation alternative in the case of process design. In this study, the evaluation and capabilities of membrane flash index are comprehensively investigated in the cases of six aqueous mixtures: methyl alcohol–water, ethyl alcohol–water, isobutyl alcohol–water, tetrahydrofuran–water, N-butyl alcohol–water, and isopropanol–water. It must be concluded that the separation capacity of organophilic type membranes is remarkably lower than hydrophilic membranes in all cases of separation. The study of the MFLI is extended with the consideration of other binary interaction parameters like separation factor, permeation flux, selectivity, and pervaporation separation index (PSI) in order to find a descriptive relationship between them. For the same membrane material type, descriptive function can be determined between feed concentration and MFLI and PSI and separation factor, which can be used to calculate each other’s value. On the basis of the indices and especially the MFLI, a significant help can be given to the process design engineer to select the right liquid separation alternative and, in the case of pervaporation, find the most appropriate membrane.

Highlights

Flash distillation is a specific method within the whole of rectification and distillation processes, where a liquid mixture is warmed up and pumped into the distillation apparatus of reduced pressure with permanent stream
Depending on the passing substance, pervaporation is classified into two major categories: hydrophilic pervaporation (HPV) and organophilic pervaporation (OPV).[1,23−27] An enormous number of practical operations and publications represent the relevance of pervaporation as a separation process in the category of membranes.[28,29]
The purpose of this study is to evaluate the membrane flash index (MFLI) in the aspects of other descriptive quantities and to extend its calculation

Summary

Introduction

Flash distillation is a specific method within the whole of rectification and distillation processes, where a liquid mixture is warmed up and pumped into the distillation apparatus of reduced pressure with permanent stream. The liquid and vapor phases are fed into a decanter (phase separator) where they are treated separately.[1,2]. The pervaporation (PV) technology is mostly applied for dehydration of organic substances,[3−9] separation of organic mixtures,[10−13] and takeout of low-concentration organic substances from their mixtures.[14−20] The separated mixture passes over a phase change in the thin film material (membrane) on account of the used vacuum at the product part that results in the permeate being in the vapor phase.[21−23] The mixture is separated by the sorption and diffusion features of a rather passing substance over a thin film membrane.[1].

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