Optimising The Conversion Of Waste Cooking Oil Into Biodiesel

Optimising the Conversion of Waste Cooking Oil into Biodiesel Supervisor: Dr. Watson

Biodiesel: a fuel comprising monoalkyl esters of long chain fatty acid. Derived from vegetable oils or animal fats. Designated B100

Important Properties: Cloud point Viscosity Alkyl esters concentration Monitored and evaluated in this project

29th August 2008

Feedstock for Biodiesel Virgin Vegetable Oil: Waste Cooking Oil: grease

Animal Fat:

yellow grease, brown

tallow, fish fat

(triglyceride: TG and free fatty acid FFA)

New feedstock under study:

Different kinds of Marine Algae

29th August 2008

Free fatty acid decrease

Cost decrease

cotton oil, sunflower seed

rapeseed oil, soybean oil,

Four Methods to Derivatize Vegetable Oils into Biodiesel Dilution: Blending with pure ethanol to reduce viscosity Microemulsion: Blending various vegetable oils with conventional fuel to decrease viscosity

Pyrolysis: viscosity

Thermal decomposition of vegetable oils to diminish the

Alcoholysis: Reaction of vegetable oils or animal fats with a short

chain alcohol to derivatize the triglycerides and fatty acid into esters to lower viscosity

Biodiesel Production Processes Acidic Esterification Equation Catalyst: H2SO4 Alcohol to FFA molar ratio >15:1

Basic Transesterification Equation Catalyst: NaOH Alcohol to TG ratio >6:1

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Materials and Equipment Materials:

Waste cooking oil Pure methanol 98% H2SO4 Sodium hydroxide pellets Ethyl acetate as GC sample solvent

Equipment: Gas chromatography machine IR spectrometry Balance U tube Thermometer Separation funnel 29th August 2008

Acid Value Determination  Determined according to BP monograph  Evaluate the weight of FFA and TG in the waste cooking oil  Estimate the proper amount of catalysts and methanol needed in biodiesel production The quality of the waste cooking oil can be very different !!!

Benefits: Help to increase the conversion rate of methyl esters and decrease the chance of soap formation and cost

29th August 2008

Viscosity and Cloud Point Comparisons between Lab Biodiesel Groups and Control Groups Groups

Cloud Point

Sample Nos

11.57°C

27

11°C

5

Lab Control

Groups

Viscosity

Sample Nos

Lab

11’34”

27

Control

12’19”

5

Boxplot of cloud point C, cloud point B

Boxplot of relative viscosity C, relative viscosity B

13.0

14

12.5

13

12.0 Data

Data

12 11.5

11

11.0 10 10.5 9

10.0 cloud point C

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cloud point B

relative viscosity C

2 sample t-test for both = no difference !!

relative viscosity B

IR and Standard Methyl Esters GC Tests Identify:

standard methyl palmitate GC calibration

IR and esters retention time on GC

y = 673191x + 4515.6 R2 = 0.9981

800000 700000

peak area

600000

Generate Calibration Equation: C (16:0), C (18:0) & C (18:1) methyl esters

500000 400000 300000 200000 100000 0 0

0.2

0.4

0.6

0.8

1

1.2

concentration

standard methyl stearate GC calibration

y = 625704x + 2614 R2 = 0.9979

700000

700000

600000

600000

500000

500000

peak area

peak area

standard methy oleate GC caliration

400000 300000 200000 100000

y = 594587x + 3553.7 R2 = 0.995

400000 300000 200000 100000

0

0 0

0.2

0.4

0.6

concentration

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0.8

1

1.2

0

0.2

0.4

0.6

concentration

0.8

1

1.2

2 Sample t-test to Evaluate the GC Experiments of Grouped Biodiesel Samples Methyl esters GC results among different stages

Methyl esters GC results between 2 groups

Stage

Total esters (mg/ml)

RSD

Groups

Acidic

0.01070.

6.7%

Basic

0.2441

2.8%

Optimized

0.7742

3.2%

Sample Nos

Lab

0.7243

27

Controlled

0.6923

5

Boxplot of controlled group, lab batches 0.90 0.85 0.80 Data

2 sample t-test: better Conversion rate of esters using the optimized method

Esters conc. Mg/ml

0.75 0.70

0.65 0.60

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controlled group

lab batches

Conclusion: Optimized Method is Better! Summary of Optimised Method:

Step 1: Determine acid value Step 2: Heat oil and remove water Step 3: Acidic esterification: heat to 50C, add 0.5 - 1.0% H2SO4, mix with 1:15 - 1:20 molar ratio of FFA to methanol

Step 4: Prepare sodium methoxide solution 30mg/ml Step 5: Basic transesterification: heat to 60 C, add 16 - 18%

sodium methoxide by weight of TG in waste cooking oil to feedstock

Step 6: Separate the top and bottom layers Step 7: Wash with warm water

Xiaoming Chen [email protected] MSc (Pharmaceutical Analysis) University of Strathclyde 29th August 2008