Ethanol yield from fruit peels and adsorption of heavy metal ions

Done by: Aman Mangalmurti

Kara NewmanLeong Qi Dong

Soh Han Wei

RationaleDepletion of non-renewable fossil

fuels due to excessive

consumption as a source of energy

Conversion of renewable

sources, e.g. organic wastes, to

fuel ensures continual energy

supplyPotential for

producing ethanol from fruit peel wastes through fermentation by microorganisms

Ethanol as a renewable,

alternative energy source

RationaleHeavy metal

water contamination of water is rampant

in many countries.

Heavy metal ions accumulate inside

organisms and cause adverse health effects

Biosorption in removal of heavy

metal ions by fruit peel wastes

Literature ReviewDemand for renewable energy resources has

increased due to increased prices for oil and concerns about global warming (Wilkins , Widmer & Grohmann, 2007)

Production of ethanol by Saccharomyces cerevisiae fromMango fruit processing solid and liquid wastes

(Reddy, Reddy & Wee, 2011)Pineapple waste (Hossain & Fazliny, 2010)

Literature ReviewIndustries such as electroplating, mining and

paint contribute to heavy metal pollution in the ambient environment

Heavy metal ions that pollute water include antimony, copper, lead, mercury, arsenic and cadmium  (US Environmental Protection Agency, 2011)

Methods of removal of ions include chemical precipitation and solvent extractionExpensive and low efficiency at low metal ion

concentrations

ObjectivesTo prepare extracts of fruit

peel for ethanol fermentation

To determine which fruit peel gives highest ethanol yield from

the fermentation of fruit peel extract

To determine which fruit peel waste gives rise to maximal

adsorption of heavy metal ions of Cu2+

,Cu3+ ions

HypothesisEthanol yield from fermentation of the

banana peel would be higher than that of the mango peel

Zymomonas mobilis produces more ethanol during fermentation as compared to Saccharomyces cerevisiae

The mango peel would adsorb heavy metal ions better as compared to banana peels

Experimental outline

Preparation of fruit peel extract

First ethanol fermentation

Heavy metal ion adsorption for Copper(II), Copper (III) ions

Second ethanol fermentation after treatment of peel residue with

cellulase

VariablesConstant

• Temperature of growth of organisms (30C)

• Initial concentration of heavy metal ions (50 ppm)

Independent

• Fruit peels used (AOS: banana, HCI: mango)

• Organism used (S. cerevisiae, Z. mobilis)

• Heavy metal ions (Cu2+ ,Cu4+)

Dependent

• Initial concentration of reducing sugars in fruit peel extracts

• Ratio of ethanol yield to initial sugar concentration

• Final ethanol yield

• Final concentration of heavy metal ions

Apparatus & MaterialsApparatus Materials Blender Sieve Boiling water bath Spectrophotometer cuvettes Spectrophotometer Centrifuge Glass rod Hot Plate Incubator Dropper Sieve: 0.25mm (60 Mesh) Shaking incubator Fractional distillator Test tubes Filter funnel Filter paper Beaker Volumetric Flask Colorimeter Quincy Lab Model 30 GC hot-air oven Measuring cylinder Magnetic stirrer Rotary mill

Mango Peel Banana Peel Deionised water Dinitrosalicylic acid (DNS acid) Zymomonas mobilis Saccharyomyces cerevisiae Glucose-yeast medium (Yeast malt extract

broth) sodium alginate medium calcium chloride solution sodium chloride solution acidified potassium chromate solution Cu2+ ion solution Cu4+ ion solution MgSO4∙7H2O 0.1 and (magnesium sulfide

hydrate) KH2PO4 0.1 (potassium phosphate) cellulase

Extraction of sugars from fruit peels

30 g of fruit peels are blended in

300 ml of deionised water using a blender.

The liquid is passed through a sieve to remove

the residue.

Determination of sugars in extractsTo 0.5 ml of

extract, 0.5 ml of DNS

(dinitrosalicylic acid) is added.

The mixture is left in a boiling water bath for 5

minutes.

4 ml of water is then added.

The samples are placed in spectrophotometer cuvettes and the absorbance is taken

at 530 nm using a spectrophotometer.

The concentration of reducing sugars in

μmol/ml is read from a maltose standard curve.

Growth of Z. mobilis

Z. mobilis cells are inoculated in 20 ml GY medium (2% glucose, 0.5% yeast extract) and incubated at 30°C for 2 days with shaking.

Immobilisation of cells

The Z. mobilis preculture and S.

cerevisiae preculture are centrifuged at 7000 rpm for 10

minutes and the cell pellets are

resuspended in 7.5 ml of fresh GY medium.

The absorbance of the cultures are taken at 600 nm.

7.5 ml of 2% sodium alginate is added to the cell suspension and

mixed well.

The mixture is dropped into 0.1 mol dm‐3 calcium

chloride solution to form Z. mobilis alginate beads.

The beads are rinsed with 0.85% sodium chloride

solution.

Growth of S. cerevisiae

S. cerevisiae cells are inoculated in 50 ml YM broth medium with the pH adjusted to 5.6 and incubated at 35°C for 1 days with shaking, before being concentrated in a refrigerated centrifuge at 10, 000 rpm.

Ethanol fermentation by immobilized Z. mobilis cells

200 beads are added to 50 ml waste extract.

A control is prepared in

which 200 empty alginate beads

are added to the same volume of waste extract

instead.

All the set‐ups are incubated

with shaking at 30°C for 2 days

for ethanol fermentation to

occur.

The beads are then removed

and the extracts are distilled to obtain ethanol.

Ethanol fermentation by S. cerisiaeTo be added

Back

Determination of ethanol yield with the dichromate test

2.5 ml of acidified

potassium dichromate

solution is added to 0.5 ml of

distillate in a ratio of 5:1.

The samples are placed in a

boiling water bath for 15 minutes.

The absorbance is measured at 590 nm using a

spectrophotometer, and the

concentration of ethanol is read from an ethanol standard curve.

Adsorption of heavy metal ions Desiccate fruit peel

residue, (put the residue in the hot air oven and dry them

at 60 degrees for 23 hours)

Using a rotary mill to grind desiccated

residue

Sieve to 0.25 mm particle size.

Add residue powder to 50ppm Cu2+

solution.

Allow solution to set for 20 min,

preferably at 100rpm to increase

contact time

Repeat for Cu4+

Determination of final ion concentration

Allow solution to set for 20 min, preferably at

100rpm to increase contact time

Remove fruit product, by filtering

the suspension

Using a copper reagent, the remaining

concentration of copper ions will be

found

Treatment of residue with cellulase

Fruit peel particles

are added into the beaker.

50 ml water is added to beaker

25ml of cellulase is added

to the beaker.

Beaker is left

standing for 1 hour

with continuous stirring.

The beaker is drained and fruit

peel is left to dry.

Second ethanol fermentation Identical to aboveEthanol fermentation

Determination of final ethanol yield

2.5 ml of acidified

potassium dichromate

solution is added to 0.5 ml of

distillate in a ratio of 5:1.

The samples are placed in a

boiling water bath for 15 minutes.

The absorbance is measured at 590 nm using a

spectrophotometer, and the

concentration of ethanol is read from an ethanol standard curve.

Applications

Cost-effective method of producing

ethanol

Reduces reliance on non-

renewable fossil fuels

Recycles fruit peels

Viable method in wastewater treatment

Timeline

Finalizing of project

details 12-23 Nov

1st round of experiments 7 Dec - Mar

2nd round of experiments Mar - May

Final round of

experiments and Data Analysis May - Jul

Bibliography Anhwange, T. J. Ugye, T.D. Nyiaatagher (2009). Chemical composition of Musa

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Retrieved June 6, 2011, From http://water.epa.gov/drink/contaminants/index.cfm Mark R. Wilkins , Wilbur W. Widmer, Karel Grohmann (2007). Simultaneous

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Retrieved on 29 October 2011 from:http://ddr.nal.usda.gov/bitstream/10113/16371/1/IND44068998.pdf

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