Maximization of ethanol yield and adsorption of heavy metal ions by fruit peels

Aman Mangalmurti Kara NewmanLeong Qi DongSoh Han Wei

Problems

Depletion of non-renewable fossil

fuels

Heavy metal ions accumulate

inside organisms and affect the

ecosystem

Heavy metal water

contamination of water is rampant

in many countries

Various diseases afflicting

bananas leads to organic waste

Rationale

Conversion of renewable

sources to fuel ensures continual

energy supply

Biosorption in removal of heavy

metal ions by fruit peel wastes

Utilizing organic waste

Problems faced

previouslyWith this project

Use of chemical water filtration methods• Expensive, unaffordable to

those who need it most• Low efficiency at low metal

ion concentrations

Affordable, accessible water filter• Helps more people in

many countries

Use of non-renewable fossil fuels• Heavy pollution

Renewable source of energy• Less pollution

GoalsTo prepare extracts of fruit peel for ethanol

fermentation

To determine which fruit peel gives highest ethanol yield

To determine which fruit peel waste adsorbs heavy metal ions best

To determine a protocol which maximizes efficiency of fruit waste

Hypothesis Ethanol yield from fermentation

differs for both peels The efficiency of heavy metal ion

adsorption differs for both peels The order of adsorption and

fermentation has an effect on the ethanol yield and the efficiency of adsorption

Experimental OutlinePreparation of fruit peel extract, microbe, heavy metal solution

Adsorption of Ions

Extraction of sugars

Ethanol Fermentation

Extraction of sugars

Ethanol Fermentation

Residue for Adsorption of Ions

•Banana PeelsAO

S

•Mango Peels

HCI

VariablesIndependent

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

• Heavy metal ions

• Order of Procedures

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

Constant• Mass of fruit

peel used• Type of

microorganism used

• Immobilisation of microorganism

• Fermentation conditions

• Adsorption conditions

• Procedures

Apparatus & Materials

APPARATUS Centrifuge Centrifuge tube Spectrophotometer Spectrophotometer cuvettes Glass rod Dropper Sieve Blender Boiling water bath Shaking incubator Fractional distillatory Quincy Lab Model 30 GC hot-air

oven Rotary Mill Sieve: 0.25mm (60 Mesh)

MATERIALS Zymomonas mobilis Glucose-yeast medium Sodium alginate medium Calcium chloride solution Sodium Chloride solution Fruit peel Deionised water Dinitrosalicylic acid Acidified potassium chromate

solution Lead (II), Copper (II), Zinc (II)

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

reagent kits

MethodsETHANOL FERMENTATIONGrowth of Z. mobilis

Immobilisation of cells

Extraction of sugars from fruit peels

Determination of sugars in extracts

Ethanol fermentation by immobilized Z. mobilis cells

Determination of ethanol yield with the dichromate test

ADSORPTION OF HEAVY METAL IONS

Pre-treatment of peel

Creation of heavy metal mixture

Adsorption

Determination of final ion concentration

Ethanol FermentationPreparation of Z. mobilis, Extraction of Sugars, Fermentation, Determination of Yield

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 to obtain the preculture.

Immobilisation of cells

The Z. mobilis preculture is

centrifuged at 7000 rpm for 10 minutes

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.

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 extracts

To 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.

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.

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 spectrophotome

ter, and the concentration of ethanol is read from an ethanol standard curve.

Adsorption of heavy metal ionsPre-treatment of peel, Creation of heavy metal mixture, Adsorption, Determination of final ion concentration

Preparation of peel powder and heavy metal ion mixture

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

residueSieve to 0.25 mm

particle size.

A mixture is made of 0.5mols of each

metal: Pb2+, Zn2+, Cu2+ in 1L of distilled

water

Add powder to mixture

Adsorption and Determination of final ion concentration

Allow solution to set for 20 min at

100rpm to increase contact time

Fruit product is removed by centrifuging

Using respective reagent kits, the

remaining concentration of

lead(II),copper (II) and zinc(II) ions will

be found.

Data analysis

•The ratio of ethanol yield to amount of initial reducing sugar

•µmol of ethanol per g of fruit peel

Ethanol yield would be

evaluate by comparing

•The ratio of the final concentrations of metal ions to the initial concentrations

•% of heavy metal ions adsorbedHeavy metal

ion adsorption efficiency would be

evaluated by comparing

Applications

Cost-effective method of producing ethanol

Reduces reliance on non-

renewable fossil fuels

Using by-product waste

Viable method in wastewater treatment

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