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Thread: Confusing problem with my biodiesel

  1. #11
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    Re: Confusing problem with my biodiesel

    Hi Arvin,

    Quote Originally Posted by Arvin View Post
    Changed the base amount to 5.5g and now the completion is awesome! Bio separated from wash water within 5 minutes, even after violent mixing.
    How long it takes the bio to separate from the wash water and how long it takes for the biodiesel and water to separate in the "Shake-um-up" test is NOT a test for biodiesel completion.
    Many things besides conversion completion can affect how long it takes the separation, including, but not limited to;
    1. Temperature
    2. How long the biodiesel has sit after finishing mixing and before the test
    3. Hardness/ softness of the water being used.
    4. Amount of soap present

    Tell you another story about some testing I did years ago.
    As you know, but some people may not know, many homes in Australia (including mine) have rain water plumbed into their houses. A third tap/ faucet next to the hot and cold town water tap/ faucet.
    I was doing "Shake-em-up" tests like you were doing and achieving some really interesting/ strange results.

    I suddenly realized that I was randomly using the rain water tap or the town water tap to perform the testing and that was what what was causing the amazingly different results.
    If you use Hard water in the "shake-em-up" test the separation will happen much quicker than using rain water. In fact rain water is often very reluctant to separate.

    The more important question is whether you were actually using methanol in your original testing
    Last edited by tillyfromparadise; 3rd April 2019 at 09:08 PM.

  2. #12
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    Re: Confusing problem with my biodiesel

    Hi Tilly,

    Thanks for the comment. I'm pretty sure that the separation time, at least in my case is a good indicator of the quality. My property doesn't have a rainwater tank, so I'll be using roughly the same quality of water all the time. Before this, I'd done about 10-12 one litre batches using 3.5g NaOH, and the first wash would consistently take hours to separate (but would separate faster from the second wash onwards).

    Also, yes, I'm using methanol in the 3/27 test - the same stuff I use as my reactant. It's from a racing supply shop, and the manufacturer says its at least 99.9% pure.

  3. #13
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    Re: Confusing problem with my biodiesel

    Also I forgot to say which vehicle I'm using it on. Firstly I will be testing this out on a diesel 2008 Volkswagen Caddy that has had roughly 330,000kms on it. So its near the end of its life, if it stuffs up it stuffs up.

    If all goes well I have a 2010 Holden Cruze that I want to power with biodiesel too!

  4. #14
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    Re: Confusing problem with my biodiesel

    Hi Arvin,

    Quote Originally Posted by Arvin View Post
    Hi Tilly,
    I'm pretty sure that the separation time, at least in my case is a good indicator of the quality.
    It can indicate whether one batch of biodiesel is higher conversion than the other. Because of the many variabilities involved, including the hardness of the water being used, it is not a recognized test for conversion quality in the way the 3/27 test is.


    Before this, I'd done about 10-12 one litre batches using 3.5g NaOH, and the first wash would consistently take hours to separate (but would separate faster from the second wash onwards).
    The fact that you used a base amount of only 3.5g NaOH suggests that these batches would not be as high conversion as your most recent batch you did using a base amount of 5.5g NaOH.
    I am surprised that the ones using 3.5g NaOH for a base amount actually passed the 3/27 test.
    Over the years I have read of a number of people who said they did not passed the 3/27 test when using a base amount of 3.5g NaOH, but as far as I can recall, you are the first person to say you did make biodiesel that passed the 3/27 test using a base amount of 3.5g NaOH.
    That is why I asked to be sure that you were actually using methanol for the 3/27 test.

    It would be interesting to see whether anyone else was able to duplicate your results- a base of 3.5g NaOH mixed into 220ml methanol and pass the 3/27 test

  5. #15
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    Re: Confusing problem with my biodiesel

    Hmm, I got 3.5g from "Journey to Forever". Keep in mind that I'm still making 1L batches using a kitchen blender running continuously for 30min so the mixing is as good as it gets. I'm not sure if I'd pass using 3.5g with a typical appleseed processor. I do agree that it would be interesting to see - try it out and let me know how you go

  6. #16
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    Re: Confusing problem with my biodiesel

    Hi Arvin,

    Quote Originally Posted by Arvin View Post
    Hmm, I got 3.5g from "Journey to Forever".
    There is a lot of good information on the Journey to Forever Site. Unfortunately there is also a lot of misinformation on the site that Keith Addison refused to change because he seemed to feel that changing them was a threat to his self perceived position as the "World Authority" on all things biodiesel.
    For a long time 3.5g NaOH was the accepted base amount required. Then an Australian chemist in Perth did some GC testing that showed that it required a base amount of 5g NaOH to meet the ASTM standard for biodiesel.

    My advice to you regarding the Journey to Forever site- A lot of the information on the site is quite useful, I use some of the chemistry charts regularly
    Do not trust any of the biodiesel formulas or procedures without first asking on this site whether they are valid.
    Last edited by tillyfromparadise; 4th April 2019 at 11:26 AM.

  7. #17
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    Re: Confusing problem with my biodiesel

    I made bio with a base rate of 3.5 for the best part of 10 years. I used an appleseed processor with a motor that thrashed the mix - it would always create a vortex all the way down to the impeller near the bottom. quite violent.

    However there was no chance that I ever made fuel that would pass ASTM standards at 3.5 grams. I'm confident you will be wasting your time testing. A couple of times I bumped it up to 5 grams to see what all the fuss was about, but like I said- the glycerine went hard within an hour or two. 40 litres of hard glycerine was a complete bugger to cut out of the brewer. I ended up using a long handle shovel, but I had to cut the handle down as it wouldn't fit inside my shed.

    I think from my own hard experience and Tilly's words of advice, that its nigh on impossible to make full conversion at 3.5g base rate with sodium.
    Last edited by Captaincademan; 5th April 2019 at 08:17 AM.
    Regards,

    Cade.

    2006 Landcruiser HDJ100 (1HD-FTE) 20,000 on bio
    2006 Ford Courier(WLT Motor), 10,000 on bio
    2002 Landcruiser HZJ105r (1HZ motor) 250,000 on bio (sold)
    2006 Mazda B2500 (WLT motor) 80,000 on bio (sold)



  8. #18
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    Re: Confusing problem with my biodiesel

    Quote Originally Posted by Arvin View Post
    Hey guys, I'm a university student interested in running my car off biodiesel. Because I'm a uni student, I really can't afford to stuff my car up so my biodiesel must be top quality before testing it out. Over the past few months, I've made dozens of 1-litre test batches of biodiesel, which seems to be very high quality:
    • No fallout at all in the 3/27 test
    • Biodiesel and water separate in under 10 minutes after my first wash.
    • Very clear water after the second or third wash - indicating very low amount of soap.
    • The soap titration doesn't even register any soap in the biodiesel! I mix 10g of biodiesel into approximately 100mL of isopropyl alcohol and add the bromophenol blue. The solution stays yellow before adding a single drop of my HCl solution. At first I thought my indicator might be stuffed, so I tested an unwashed sample of bio and got approximately 2,000 ppm, and that sounds about right for unwashed biodiesel.


    Ok so all of this means that it should be good to use, but when I shake the bio up with water, it forms a very soapy looking layer between the water and biodiesel. This layer goes away pretty quickly, but just the sight of it makes me think there's still soap in it. But then my tests are indicating that the soap levels are quite low.

    What do you guys think? Am I over-reacting, and is it normal for the biodiesel to look very soapy even when the soap levels are low?
    What is a soap test?

  9. #19
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    Re: Confusing problem with my biodiesel

    Quote Originally Posted by WesleyB View Post
    Biodiesel is a methyl fatty acid ester. It is usually made by transesterification, which is described in an organic chemistry book I have. Biodiesel is made from a glyceride tri-fatty acid ester. The long chain (3) fatty acids are bound through a carboxylic acid head on the fatty acid to the glyceride which is a three carbon chain. I don't know how to draw it on a computer. In transesterification the fatty acids switch their bond from glyceride (a polyalcohol) to methanol a mono-alcohol. The ester switches from one alcohol to another (trans-change). I'm not sure but your observed third layer might be mono and di glycerides where the reaction has not gone to completion. A di-glyceride as opposed to a tri-glyceride is one of the fatty acids of the three has become biodiesel, but two more fatty acids remain bonded to the glycerine/glyceride. A monoglyceride has one fatty acid left bonded to the glyceride. The mono and di-glycerides bonded to fatty acids hydrogen bond with water, they are not soap. This might indicate an under reaction. Increase temperature, time and or amount of caustic catalyst to get a more complete reaction. And make sure the oil being used is dry. Also during the normal reaction vigorous mixing must be done. Methanol floats on vegetable oil. The alcohol must be mixed throughout the vegetable oil for the reaction to proceed properly.
    Few comments:

    1. mono and diglycerides are more reactive than triglycerides. So in a reaction that hadn't gone to completion you'd find some triglycerides but virtually no mono and diglycerides.

    2. The observation is probably explained by the fact that as an ester, the bio has some hydrogen bonding properties with water, so when you shake it with water the layers won't separate as quickly as if you'd used a straight hydrocarbon. But they do separate "pretty quickly."

    3. You don't need to dry your oil if you use my method. If you are using the Dr Pepper method you are adding far more water to your mixture with the methoxide solution than any drying of your oil will remove

    4. If the reaction is incomplete, then heating it more will work with the Dr Pepper method, as it is a method that requires heating. OTOH if you use my method you don't need to ever heat.
    F

  10. #20
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    Re: Confusing problem with my biodiesel

    Quote Originally Posted by Dr Mark View Post
    Few comments:

    1. mono and diglycerides are more reactive than triglycerides. So in a reaction that hadn't gone to completion you'd find some triglycerides but virtually no mono and diglycerides.
    Hi Mark, not questioning your chemical knowledge but I don't think that statement is true. I've done dozens of tests adding varying excess amounts of KOH to my process and used a range of temperatures. The emulsified layer sometimes present between the wash water and biodiesel is minimal when adding excess catalyst after a clear 10/90 warnqvist test. However with a clear warnqvist test (presumably just on the cusp of conversion) the emulsified layer can be substantial. I can't actually prove it as I have no G/C available to me but I am pretty sure the emulsion is due to mono's and to a degree diglycerides.

    Also re your above statement the triglyceride molecule has to go through the diglyceride and monoglyceride phase before being fully converted so it would seem your statement really needs to be the opposite way round.

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