SEED OIL ANALYSIS

Back to school! Continuing from where we left off, we have our oil, and it had started to form solid particles. There was a layer of solid particles forming in the oil.

We've found out the reason why two layers form on our oil, and the reason behind the solidifying of our oil. To explain this, we need some background information on the components inside oil.
The rambutan seed oil here consists of different fatty acids. Fatty acids are critical components found in oil. 

There are saturated and unsaturated fatty acids. A saturated fatty acid does not have any carbon-carbon double bonds, and hence its chemical structure is rigid. This rigid chemical structure causes the common saturated fatty acid to be in solid form. An unsaturated fatty acid consists of carbon-carbon double bonds and as such its chemical structure is bent. Unsaturated fatty acids are commonly liquid as their structures are not rigid. 

However, these fatty acids do not exist in this pure form. If they do exist as just fatty acids in the oil, they would be Free Fatty Acids (FFAs). However, in normal ambience form of oil, there's very little FFAs. Three of these fatty acids combine together with glycerol to form a triglyceride.

 These triglycerides could consist of any combination of three fatty acids (denoted by R', R'' and R''') here. Going back to saturated fatty acids, if these saturated fatty acids form saturated triglycerides, these triglycerides would have rigid structures, being in solid form. However, more unsaturated triglycerides would be more liquid-form.

This explains why our oil tends to have solid particles settling. Saturated triglycerides are forming, triglycerides get more rigid in nature, forming solid particles. Saturated FFAs also contribute to this.

Due to this, we have to reheat our oil before we are able to use it again. We reheated at about 50-60 degrees celsius. 

After which, we are able to find out the oil's properties.

Volume of oil = 9.4 mL
Mass of oil = 3g
Density of oil = 0.319 g/mL
Yield of oil by soxhlet extraction = Mass of oil/Mass of seeds = 3g/101.37g = 2.96%

The reason for our low yield is because we realised a few mistakes we did when preparing the crushed seeds. We dried it at 1100C for 20 minutes. We should have dried it at a temperature lower than 80 degrees celsius, or else the oil content in the seeds would also be dried up. There was a high probability that a significant portion of the oil content was already dried up when we tried to dry the seeds.

Another possible reason for this low yield is the soxhlet extraction was run only for 6 cycles. We had a shortage of time due to Christmas break and also New Year's so we stopped at 6 cycles. The average rate was 1 to 1.5 cycle per hour.

A higher number of cycles would generate more oil from the seed stack.
An appropriate number of cycles we should do for soxhlet extraction should be 20. 

We also conducted a flammability test and it was successful, the oil burnt readily, signifying that the oil is of good quality since it is flammable. The oil was put on a fiber wick and it was lit up, and the oil caught fire and continued to burn even after we disposed it into the drain.



When we vacuum filtrated and distilled ethanol out from the ethanol and bio-oil mixture from the round-bottomed flask, we only got a small volume of oil.

To prove its true suitability of yield in generating bio-oil from rambutan seeds, we need to re-do the drying and the soxhlet extraction.

However, we searched around in Clementi, Woodlands, Yishun, Jurong, Bedok, Tampines, and Naeem even asked his relatives in JB, Malaysia if there was any rambutan fruits growing but we all got the same answer, 'It's not in season right now'. We should've bought more back in December.

We were disappointed by this. Nevertheless, lets just carry on with what we have!


COMING UP: PREPARING FOR THE LONG AND ARDOUS TRANSESTERIFICATION!!!
STAY TUNED

SEED OIL

24 December, Christmas Eve! Merry Christmas! Feliz Navidad! Buon Natale! Lab is open for half day only and we need to do stuff pronto. 

From the soxhlet extraction, we managed to retrieve the seed oil from the round bottom flask. However, it is contained with a lot of impurities. Hence, we need to purify to obtain a pure oil sample. 

We performed suction filtration with a vacuum pump to remove any impurities in the extracted rambutan oil. By using Vacuum filtration, it speeds up the process of filtration, as compared to the conventional filtration method.

After filtration, the oil was free from impurities.

We then proceeded with simple distillation, with the temperature set around 80°C to remove the ethanol in the oil. The boiling point of the ethanol is around 78°C. At 80°C, all the ethanol content in the oil will vapourised and condense as distillate.

The distillate (ethanol) was removed and disposed.

After distillation, the extracted rambutan oil were seen to have a darker colour.

The oil was left to cooled and then stored in a small glass bottle. After letting the oil to cool, there seemed to be 2 layers in the oil.

Next episode on RAMBUTAN EXTRACTION SERIES, Transesterification! In the next episode, the J-team faces another challenge, how to convert the seed oil into biodiesel? Transesterification? WHATS THAT?? Can they obtain the necessary equipment and ingredients to perform this daunting task? STAY TUNED ON CHANNEL J!

SOXHLET YOOOO

We went to W315 (we forgot to book but lucky us there's empty slot yay) and then we performed soxhlet extraction using the soxhlet apparatus provided. 200ml of ethanol was used to extract the oil from the rambutan seeds. 

We used soxhlet extraction because it is a more efficient method as compared to the use of mechanical press.

 As soxhlet extraction uses the theory of washing the sample over and over again with the use of the solvent, it has the ability to obtain more bio-oil. Furthermore, soxhlet is able to isolate desired oil, which has limited solubility in the solvent and the impurity is insoluble in a solvent. Thus making the bio-oil have higher purity. 

We used soxhlet extraction because it is a more efficient method as compared to the use of mechanical press.

As for the use of ethanol, it was decided upon when the use of n-hexane was deemed too dangerous to be used as the flash point was way too low, which may cause imminent danger to the user. Ethanol is a safer solvent to use compared to n-hexane. We don't wanna die yet, we're too young.

The experimental setup is shown below.

Ethanol was heated so that it can be vaporised, it is being heated through water bath as the round flask heater was faulty (take note).

This gif illustrates the intended process of soxhlet extraction. Ethanol vaporises, then condenses on the seed stack. Condensed ethanol is collected, and when the return tube is full, the seed stack is submerged, the reservoir will fall back to the flask.

We did soxhlet extraction for about 2 hours then we noticed that there wasn’t any significant differences. Progress was very minimal. The ethanol was supposed to vaporise and then condense back, and cause the seed stack to become wet. We noticed ethanol condensing but it was only a few droplets even after two hours. Wow we could've used the two hours to do so much other things but alas

We suspected that the cotton layer was too thick (sometimes you shouldnt 'play safe' too much by adding too much), hence we removed a huge portion of it.

Due to the thick cotton layer, all the condensing ethanol is soaked in by the cotton, thus, only little ethanol is able to come into contact with the Rambutan seeds.

Hence, when the cotton layer is reduced, ethanol is able to pass through easily and perform leaching. The time of the process is also significantly reduced.

After which, ethanol was able to condense at a fast rate. Finally we weren't waiting so much for nothing!

We took around 6 hours to complete soxhlet extraction. In the meanwhile, we spent hours doing things and talked about almost anything. Other than that we were on our phones on social medias, we keep refreshing our timelines in the hope of seeing new posts, we bugged other busy people on Whatsapp, trying to talk to them, we walked around campus on an expedition (we took turns in shifts) just to pass time and we watched horror movies (yes in bright daylight). We monitored the process in the meanwhile of course.

We managed to do six cycles of soxhlet extraction. A total of 8 hours were spent.

A cycle is completed when the return tube is completely full, the seed stack is completely submerged with condensed ethanol, and then the return tube will empty itself along with the seed stack. The liquid reservoir on the seed stack will flow down to the round-bottom flask that contained ethanol.

During the sixth cycle, the solvent at the sight glass started to become quite clear, hence, we decided to stop the experiment. Finally we're done for the day. But nope, tomorrow still need go lab. At least soxhlet extraction is done!

CRUSHING SEEDS

            

After eating (and making rambutan syrup with F&N rose syrup -I recommend this- ) 46 rambutans, this is what we got; 46 seeds. Doesn't seem that much from here but trust us we took long to finish it.

All the flesh on the rambutans were removed till the seed is left, bare naked.

Initially, we tried to use a mortar and pestle to grind the rambutan seeds into finer pieces. However, we realised it takes too long. Of course it does. Naeem's mom scolded us and said 'Do you want to do this till night?!'

In the end, we employed the help of a wet blender and managed to use it to shred the rambutan seeds into finer pieces. It was noisy, shredding the seeds between the blades. This blender is supposedly used for food with very wet mediums.

1.4. The seeds were spread out evenly on the tray.

Then, the seeds were dried in an oven to remove moisture in the seeds at 1100C for 20 minutes.  

After drying, the total mass of seeds weigh 101.37g. The seeds smell nice. Baked seeds. Remember how even the rambutan seeds is beneficial? We should eat them. Wait, no we need to make biodiesel.

INTRO

HEY!!!!11!!!!1!!! Firstly, let us introduce ourselves; we are THE AWESOME J TEAM

- CONSISTING OF NAEEM, XING HUI, HONG WEI AND J FROM DCHE 2B/05 (we r very fun and cool peeeople to be with k)!!!

Our group will be using this blog to keep updates on our Green Engineering YES Assignment. For our YES assignment, we decided on using rambutan seeds, cause seeing how we're living in the Southeast Asia, a common fruit in this region would be unique and also easy to get. We will be converting rambutan seeds into oil first through soxhlet extraction, then we will convert into our final product, biodiesel through transesterification.

(mmm, just looking at that makes you want to savour them) 
Rambutan is also favourable in making oils, as it has 39% oil percentage in its seeds, higher than its 'rivals', other native to southeast asia fruits like lychee and longan. 
Rambutan is always coined with the term 'exotic superfruit', it has a lot of benefits when eaten (strong antioxidant, increase immunity, cure common illnesses, boosts energy, lower sugar levels etc etc etc)

Even if it is not consumed, it still brings a lot of benefits to the table! (bark can get rid of thrush, roots as repellent to remove internal worms in fruits, leaves to cure headache, fruit skin layer made into decoction can remedy dysentry)

Our plan is firstly to use soxhlet extraction to extract oil from the rambutan seeds.

We chose soxhlet extraction because it is a more efficient method as compared to the use of mechanical press.

As soxhlet extraction uses the theory of washing the sample over and over again with the use of the solvent, it has the ability to obtain more bio-oil. Furthermore, soxhlet is able to isolate desired oil, which has limited solubility in the solvent and the impurity is insoluble in a solvent. Thus making the bio-oil have higher purity.

In order for efficient soxhlet extraction, the seeds are to be grinded into small pieces and also dried to remove moisture content.

After extracting oil, we would proceed with transesterification to produce our desired biodiesel, in which glycerin will also be produced. 

We'll see you later for more updates and we'll explain further!