Perspectives and limitations of using on-line mass spectrometry for monitoring of pervaporation processes

Abstract

Organophilic pervaporation has a high potentialfor aroma recovery from dilute aqueous solu-tions because it involves a low energy inputwhen compared with other separation processessuch as distillation; also, it operates at mildconditions allowing for a direct recovery ofaroma compounds from fermentation processesor other complex media.In traditional pervaporation systems, acomplete condensation of permeate occurs in asingle condenser. Aiming to fractionate the per-meate stream, in order to obtain defined aromaprofiles, this study involves the use of a pervapo-ration module followed by two condensers inseries operating at different temperatures, allow-ing for a fractionated condensation. Due to thedifferent relative volatilities of the different com-ponents of the system, an increase on the globalseparation factor may be achieved. This approachrequires an optimisation of the temperature(s) ofcondensation in the downstream circuit. Mass spectrometry (MS) has proved to be apowerful analytical tool with high precision andsensitivity. In this work, we evaluate its domainof applicability as an on-line monitoring toolcoupled with pervaporation (PV). Coupled MS/PVhas a high potential for the understanding of PVsystems because it allows for on-line monitoringof each component of the permeate stream,enabling transient studies and reducing experi-mental workload signific antly when varying anyexperimental parameter.