Ethanol yield from fruit peels and adsorption of heavy metal ions

Group: 1
-
124

Leong Qi Dong

4S216

Soh Han Wei

4I324

Aman

Mangalmurti

AOS

Kara Newman


AOS

Depletion of non
-
renewable fossil
fuels

Heavy metal water
contamination of
water is rampant in
many countries

Heavy metal ions
accumulate inside
organisms and affect
the ecosystem

Conversion to
biofuel, ensuring
continual energy
supply

Biosorption

in
removal of heavy
metal ions by fruit
peel wastes

Fruit peel waste

Ethanol
Fermentation

Shorter fermentation
time (300%
-
400%
faster than yeast)

higher ethanol yield
(92%
-
94% versus
88%
-
90% for yeast)

Microorganism
used:

Zymomonas

mobilis

Nguyen, T., and
Glassner
, D. (2001 )

To investigate the production of ethanol from
fruit peels

To investigate the efficiency of adsorption of
heavy metal ions by fruit peels

To determine the procedure which
maximises

ethanol yield and efficiency of heavy metal
ion adsorption


Mango peels contain reducing sugars that
can be fermented to ethanol.


Mango peels show different efficiency levels
in the adsorption of copper, zinc and lead
ions.

Preparation of
fruit peel extract,
microbe, heavy
metal solution

Extraction of
sugars

Ethanol
Fermentation

Residue for
Adsorption
of
Ions

Adsorption
of
Ions

Extraction of
sugars

Ethanol
Fermentation

•
Mango
Peels

Fruit
tested

•
Pb
2+

•
Cu
2+

•
Zn
2+

Ions
tested

Independent

•
Heavy metal ion
(Pb
2+
, Cu
2+
, Zn
2+
)

•
Sequence of
procedures

Dependent

•
Initial
concentration of
reducing sugars in
fruit peel extracts

•
Ratio of ethanol
yield to sugar
concentration

•
Amount of ethanol
per g of fruit peel

•
Final concentration
of heavy metal
ions

Controlled

•
Mass of fruit peel
used

•
Type of
microorganism
used (
Z.
mobilis
)

•
Duration and
temperature of
fermentation


Centrifuge


Centrifuge tube


Spectrophotometer


Glass
rod


Sieve


Blender


Dry blender


Shaking incubator


Oven


Incubator


Weighing Balance


Zymomonas

mobilis


Glucose
-
yeast medium


Sodium alginate


Calcium chloride solution


Sodium chloride solution


Fruit peel


Cuvettes


Deionised water


Dinitrosalicylic

acid


Acidified potassium chromate solution


Lead (II), Copper (II), Zinc (II) ion solutions


Copper (II) and Zinc (II) reagent kits


Preparation of
Z.
mobilis
, Extraction of Sugars, Fermentation,
Determination of Yield

Growth of
Z.
mobilis

Immobilisation

of cells

Extraction of sugars from fruit peels

Ethanol fermentation by immobilized
Z. mobilis

cells

Determination of ethanol yield with the dichromate test


Ethanol fermentation

Z.
mobilis

cells were inoculated in 20 ml GY
medium (2% glucose, 0.5% yeast extract)

Incubated at 30
°
C for 2 days with shaking for
growth to occur

Culture was
centrifuged at
7000 rpm for 10
min

Cell pellets were
resuspended

in
7.5 ml GY
medium.

Absorbance of
the cultures
were taken at
600 nm.

7.5 ml of 2%
sodium alginate
is added to the
cells.

Added
dropwise

to 0.1 M calcium
chloride solution
to form beads.

Beads were
rinsed in 0.85%
sodium chloride
solution.

40 g of fruit
peels were
blended in 400
ml of deionised
water using a
blender.

The extract was
passed through
a sieve to
remove the
residue.

Suspension was
centrifuged at
7000rpm.
Supernatant
and residue
were collected.

200
Z.
mobilis

beads were
added to 50 ml
mango peel
extract.

Control : 200
empty beads
were added to
the same volume
of mango peel
extract.

Set
-
ups were
incubated with
shaking at 30
°
C
for 2 days for
ethanol
fermentation.

Beads were
removed and the
extracts are
distilled to obtain
ethanol.

2.5 ml of acidified potassium dichromate
solution was added to 0.5 ml of distillate.

Samples were placed in a boiling water
bath for 15 min.

Absorbance was measured at 590 nm
using a spectrophotometer

Concentration of ethanol was read from
an ethanol standard curve.

Dessication

of peel, Preparation of ion solution, Adsorption, Determination
of final ion concentration

Fruit peel
residue
was dried
in an oven.

Dried peel was
blended to
powder using the
dry blender.

0.2g fruit peel powder
was added to 10ml 50ppm
of each ion solution (test).
No peel was added in the
control set
-
up.

Mixtures were
placed on a
rocker for 24 h
at room
temperature.

Peel powder
was removed
by
centrifugation
.

Using reagent kits for copper
(II) and zinc(II) and AAS for
lead (II) the final
concentration of ions in
solution was determined.

•
µmol of ethanol per g of fruit peel

Ethanol yield

•
% of heavy metal ions adsorbed

•
(Final
-
Initial)/Initial x 100%

•
t
-
test to determine if difference between
the control and the test is significant

Heavy metal ion
adsorption
efficiency

y = 0.8101x
-

0.0691

R² = 0.9969

0.0
0.5
1.0
1.5
2.0
2.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Absorbance at 530 nm

Maltose concentration / µmol/ml

Maltose standard curve

y = 0.6392x
-

0.0034

R² = 0.9996

0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0
0.5
1
1.5
Absorbance at 590 nm

Concentration of ethanol / %

Ethanol standard curve

Sugar Extraction First, Ethanol Fermentation, Ion Adsorption

0.196

0.205

0.00
0.05
0.10
0.15
0.20
0.25
0.30
1
2
Concentration of ethanol / %

Ethanol yield from mango peels

46.5

63.2

36.2

9.4

26.3

1.9

0
10
20
30
40
50
60
70
Copper
Zinc
Lead
Final concentration of ions / ppm

Adsorption of ions by mango peels (1st
round)

Control
without
peels
Test with
mango
peels
45.9

53.8

32.5

4.4

15.8

0.5

0
10
20
30
40
50
60
Copper
Zinc
Lead
Final concentration of ions / ppm

Adsorption of ions by mango peels (2nd
round)

Control
without
peels
Test with
mango
peels
Ion

t
-
test p value to show difference between
control and test

Round 1

Round 2

Copper

0.000399

0.000229

Zinc

0.00037

0.00101

Lead

0.00001

0.000405

All differences were significant as p < 0.05

85.1

64.5

96.6

0
20
40
60
80
100
120
Copper
Zinc
Lead
Ion adsorbed by mango peels / %

A comparison of the efficiency of adsorption of
ions by mango peels

Ion
Adsorption First, Sugar Extraction, Ethanol Fermentation

48.6

51.2

55.3

15.0

33.3

4.3

0
10
20
30
40
50
60
Copper
Zinc
Lead
Final concentration of ions / ppm

Adsorption of ions by mango peels (1st
round)

Control
without
peels
Test with
mango
peels
50.4

51.6

32.4

19.8

31.7

5.8

0
10
20
30
40
50
60
Copper
Zinc
Lead
Final concentration of ions / ppm

Adsorption of ions by mango peels (2nd
round)

Control
without
peels
Test with
mango
peels
49.0

51.2

31.9

15.1

24.4

7.2

0
10
20
30
40
50
60
Copper
Zinc
Lead
Final concentration of ions / ppm

Adsorption of ions by mango peels (3rd
round)

Control
without
peels
Test with
mango
peels
Ion

t
-
test p value to show difference between
control and test

Round 1

Round 2

Round

3

Copper

0.0000000723

0.000485

0.000000139

Zinc

0.000542

0.002072

0.000619

Lead

0.00000471

0.004109

0.00000225

All differences were significant as p < 0.05

64.9

36.7

87.2

0
10
20
30
40
50
60
70
80
90
100
Copper
Zinc
Lead
Ion adsorbed by mango peels / %

A comparison of the efficiency of adsorption of ions
by mango peels

Ethanol yield

Extraction of sugars
first

Adsorption of
ions first

Round 1

Round 2

Round 1

Mean ethanol
concentration / %

0.196

0.205

0.223

Amount of ethanol / µmol

334.91

351.88

382.25

Amount of ethanol / µmol
per g of fruit peel

66.98

70.38

148.02

Sequence 2 (Adsorption of ions followed by extraction of
sugars) resulted in a higher yield of ethanol

Metal ion

Mean % of ions adsorbed

Extraction of
sugars first

Adsorption
of ions first

Copper ion adsorbed / %

85.1

64.9

Zinc ion adsorbed / %

64.5

36.7

Lead ions adsorbed / %

96.6

87.2

Sequence 1 (Extraction of sugars followed by adsorption
of ions) resulted in higher efficiency of adsorption of ions

C
-
H
stretch

Some changes in the
1000
-
1800cm
-
1
wavenumbers

weaker
C
-
H
stretch


Adsorption of ions has resulted in changes in
FTIR
spectra


Weaker C
-
H stretch after lead ion adsorption


Stretching of more bonds in between 1800
-
1000 cm
-
1

after all three ion adsorption


We
believe that the carboxylic
acid, ester and
lactone

(1700cm
-
1
) and
alkene groups
(1600cm
-
1
)
are responsible for adsorption.







Difficulty in
standardising

batch of mango
peels for all tests performed


May yield inconsistent results for each repeat

Cost
-
effective
method of
producing ethanol

Reduces reliance
on non
-
renewable
fossil fuels

Using by
-
product
waste

Low cost, viable
method in
wastewater
treatment


Investigate the effect of pH of ion solution on
adsorption


Investigate the production of ethanol and
adsorption of ions on peels of other locally
available fruits such as pineapple


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, T. J.
Ugye
, T.D.
Nyiaatagher

(2009). Chemical composition of Musa
sapientum

(Banana) peels.
Electronic Journal of Environmental, Agricultural and Food Chemistry,
8
,
437
-
442.

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http://ejeafche.uvigo.es/component/option,com_docman/task,doc_view/gid,495


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
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