Biodiesel Production from Spent Coffee GroundsAnthony Goh and Dr. Enrico N. Martinez School of Chemical Engineering, Purdue University, West Lafayette, IN USA 47906

AcknowledgementsSpecial thanks to:

• Katie Westfall, Port Café for supplying the spent coffee

grounds

• Dr. Bryan Boudoris for utilization of his laboratory space

and equipment

• Rohit Jaini for guidance on running GC-MS and data

interpretation

• Rick McGlothlin for assisting in the experimental setup

Did you

know?Coffee is the second most heavily traded

commodity only after petroleum and the largest food

import of the United States.

The global production number of coffee is

around 8 million tonnes per year with an increasing

demand every year. Thus, a sustainable coffee

industry requires the development of methods for

utilization of coffee byproducts.

This research project utilizes Soxhlet extraction method for the oil extraction process which then undergoes transesterification reaction to produce biodiesel. Preliminary results reveals that the maximum yield of coffee oil in spent coffee

grounds (SCG) is around 20 wt% and is dependent of the solvent used. Oil to biodiesel conversion is around 32.7 – 53.7% depending on the type of catalyst used and the operating conditions of the experiment.

0

10

20

30

40

50

60

1 2 3 4 5

37.1439.66

53.72 52.67

58.2

Perc

enta

ge (

%)

Sample Runs

Oil to Biodiesel Conversion

0

5

10

15

20

25

0 50 100 150 200 250 300

% Y

ield

Time (min)

Percentage Yield of Coffee Oil vs.

Time

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10

% Y

ield

Sample Runs

Percentage Yield of Coffee Oil

Extracted

Hexane

Heptane

How?Future Directions• More repeated data to understand and produce the

reaction rate equation

• Analyze quality of biodiesel produced

• Analyze the system design and operating processes used

in industrial large scale production

References• L.S. Oliveira, A. S. Franca, R. R.S. Camargos, V. P.

Ferraz, Coffee oil as a potential feedstock for biodiesel

production, Biores. Technol., 99, 2008, 3244-3250.

• Z. Al-Hamamre, S. Foerster, Fr. Hartmann, M. Kröger, M.

Kaltschmitt, Oil extracted from spent coffee grounds as a

renewable source for fatty acid methyl ester

manufacturing, Fuel, 96, 2012, 70–76.

Conclusion• Operating temperature, type of solvent used for extraction

process, time affects the yield of coffee oil

• Immobilized enzyme catalyst L3170 is more effective than

soluble L4777 in oil to biodiesel conversion

• Max. yield of coffee oil from spent coffee grounds is around

20 wt% and is dependent on solvent used

• Oil to biodiesel conversion is around 32.7-53.7%

dependent on catalyst used and operating conditions

• GC-MS peaks detect presence of fatty acids palmitic,

linoleic, oleic and stearic

Sample

Run No.

Catalyst used

1 L4777 Repeated runs at fixed operating

conditions*2 L4777

3 L3170 Repeated runs at fixed operating

conditions*4 L3170

5 L3170 Increased temperature to 60C

Results

Transesterification – Catalyzed biochemical process

involving the conversion of a triglyceride (fat/oil) with

an alcohol to form esters and glycerol

Why?As the world’s fossil fuel reserves are depleting

rapidly, the demand for a more sustainable alternative

has risen. Alternatives that are scientifically

possible, environmentally acceptable and

technologically possible are being researched.

Biodiesel currently is known as one of the most

promising alternative energy source capable of

replacing fossil fuels in the future.

Solving two global concerns

• Reduction/Elimination of coffee waste

• Alternative to clean, cheap energy production

Separate and Recover

• Rotary evaporator

• Solvent recovery

(hexane/heptane)

• Immobilized enzyme can

be reused

React and Analyze• Transesterification

• Enzyme catalysis

• Immobilized (L3170)

• Soluble (L4777)

• Solution in reactor (methanol,

hexane, catalyst , coffee oil)

• Operating condition varied

• Analyzed using GC-MS

*Note: 140mL of methanol, 600 mL n-Hexane, 200 rpm stirrer speed, ~2g

of catalyst, 12g of coffee oil. Operating temperature at 50C

Extract and Filter• Soxhlet extractor via solvent

(heptane/hexane) extraction

method

• ~25g of SCG loaded into

cellulose thimble

• 600 mL of solvent/run

• Heated to sample’s B.P.

‘

Collect and Dry

• Placed in an isotemp

incubator operating at

70C

• Minimize/Eliminate

moisture content in

spent coffee grounds

(SCG)

Fatty Acid Chemical StructureConcentrations

(mM)

Weight

(%)

Palmitic

(C16:0)CH3(CH2)14COOH 6.678652 35.660

Stearic

(C18:0)CH3(CH2)16COOH 3.582774 19.130

Oleic

(C18:1)

CH3(CH2)7CH=CH(CH2)

7COOH0.926101 4.948

Linoleic

(C18:2)

CH3(CH2)3(CH2CH=CH)

2(CH2)7COOH1.003957 5.360

• Consistency in repeated data

• Higher coffee oil yield using hexane

• ~3 hours to reach max yield

• Higher biodiesel conversion using catalyst L3170

• Increasing T increases biodiesel conversion

Gas Chromatography Results