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IN

recent years, the use of renewable resources has

been explored to produce biodegradable materials

that can reduce the waste disposal problems

caused by the petrochemical-based polymers. Films of different

polysaccharide materials have been produced, including chitosan,

starch and carrageenan, mainly because they are biodegradable,

non-toxic and widely available. The use of microbial

polysaccharides has also increased because they represent an

advantageous alternative to others recovered from animals or

plants. They only depend on the microbial cultivation parameters,

which may be easily controlled. However, their wide spreading has

been hindered mainly by their production costs, which are higher

than most of the traditional petrochemical-based polymers. Thus,

several agricultural and industrial wastes and byproducts have

been proposed as substrates for microbial cultivation as a

strategy to lower the production costs.

Recently, the glycerol-rich byproduct from biodiesel production

was used to produce a high molecular weight negatively charged

exopolysaccharide (FucoPol), composed of sugars (galactose,

glucose, fucose) and acyl groups. This biopolymer produced at the

Biochemical Engineering Group was used to obtain dense and

transparent films. They show a high hydrophilic character and

good gas barrier properties, as well as being insoluble in most

common solvents, such as ethanol, dichloromethane, acetone,

toluene and ethyl acetate. Due to their unique characteristics, two

different applications were envisaged and the following projects

are being co-ordinated by Professor Isabel Coelhoso at the

Laboratory of Membrane Processes of LAQV@REQUIMTE:

(i) Food packaging films to extend shelf life of food products; and

(ii) Membranes for solvent dehydration by pervaporation.

FucoPol films for food packaging

One of the most important parameters in food packaging is the

ratio of the CO

2

/O

2

permeabilities (selectivity,

α

), which

determines the relative proportion of carbon dioxide and oxygen

in the package. For FucoPol films, the obtained selectivity (

α

=62)

is much higher than the values referred for biopolymers, chitosan

(

α

=11) or starch (

α

=24), and for synthetic polymers, namely

LDPE (

α

=4) and PET (

α

=3). FucoPol films show higher barrier

properties to oxygen than LDPE films, maintaining similar values

for carbon dioxide permeability. Thus, FucoPol films can be

advantageously used in modified atmosphere packaging with low

oxygen content. The properties of FucoPol films can still be

improved using plasticisers, cross-linking agents and blends with

other biopolymers.

Membranes of FucoPol for ethanol dehydration

by pervaporation

Compared to distillation technology, pervaporation has been

identified as one of the most efficient separation processes for

dehydration of bioalcohols, with energy savings of up to 50%.

Composite polysaccharide membranes, with a FucoPol active

layer supported on a polyethersulfone membrane, were used for

ethanol dehydration by pervaporation. This membrane presents a

water permeability which is the double of that obtained with the

commercial membrane PERVAP® 4101, and a selectivity

water/ethanol five times lower. This will translate into a higher

throughput (a lower membrane area is required), but a greater

loss of ethanol will take place through the permeate side. Future

work includes the optimisation of membranes with enhanced

water selectivity in order to explore the promising results of this

exopolysaccharide for other solvents’ dehydration.

Isabel Coelhoso

Assistant Professor

LAQV, Requimte

Departmento de Química

FCT-Universidade Nova de Lisboa

te l :

+351 212 948 302

imrc@fct.unl.pt http://www.requimte.pt/laqv/people/isabelcoelhoso

With growing environmental concern, it is crucial to develop membranes from

renewable sources with good performance and reliability. Professor Isabel

Coelhoso highlights her main achievements in the topic

Novel membranes

from biopolymers

www.horizon2020projects.com

H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L

I S S U E S E V E N

73

P R O F I L E

N AT I O N A L F O C U S : P O R T U G A L