To investigate the membrane behavior, first model solutions of
ethanol/water were separated in pervaporation experiments to
characterize ethanol transfer across the hollow polydimethylsiloxane
(PDMS) membrane and these results provided the reference for
the broth experiments.
In the first case, feed conditions (flow rate, temperature, ethanol
composition) and permeate pressure were modified. Also, the time
necessary to reach steady state was determined. Then, tests were
performed with the fermentation broth produced using banana
fruit waste as a substrate varying the ethanol feed mass fraction
and feed flow rate. The presence of some byproducts was also
studied.
2.1. Membrane
The pervaporation unit used consisted of a removable permeation
module made of polyvinyl chloride (PVC) of 0.2 m internal
diameter containing 50 dense hollow polydimethylsiloxane
(PDMS) membranes (di = 0.6 mm and de = 1 mm), 0.25 m in length,