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Thread: Adding some glycerine to WVO to lower ...

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    Adding some glycerine to WVO to lower ...

    I've heard that adding some glycerine to the WVO can lower titration.
    Can you do this using glycerol that is the drain-off from a 5% pre-wash or is there too much water in the solution?
    George

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    Re: Adding some glycerine to WVO to lower ...

    Hello George

    People have reported that mixing the glycerine layer from a prevous batch of biodiesel both cleans the oil and lowers the titration.
    I would be concerned about using glycerine that has been used with a 5% wash. You would need to do some tests

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    Re: Adding some glycerine to WVO to lower ...

    Quote Originally Posted by tillyfromparadise View Post
    Hello George

    People have reported that mixing the glycerine layer from a prevous batch of biodiesel both cleans the oil and lowers the titration.
    I would be concerned about using glycerine that has been used with a 5% wash. You would need to do some tests
    Hello Tilly,
    How are things with you today?

    Regarding adding glycerine to WVO:
    Do you know if those who do this process, do it with the glycerine added to the mix, or do they mix in the glycerine, allow to settle, then remove the glycerine (if it separates) prior to processing?

    On another note:
    After a batch has reacted and separated, would you have a idea of how much glycerine could be removed before attempting a 5% pre-wash with the remainder of the glycerine without producing an emulsion.
    George

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    Re: Adding some glycerine to WVO to lower ...

    Hello George
    I am very well today, I just got the Iron lung overhauled.

    No, do not leave the glycerine in the WVO for the reaction. It is likely to act as a "Methanol Sponge" and remove some of the methanol from the reaction.

    I do not know how much you can remove and still not make an emulsion.

  5. #5
    David Guest

    Re: Adding some glycerine to WVO to lower ...

    I have done this and can confirm it works both at helping the oil to settle out the crap and in lowering the titration...Quite a bit in the tests I have done.

    I used glyc from a 5% wash and it worked fine but I did not make bio with the oil so I cannot say how it went for water content. What I have read on other forums suggests people find the glyc helps pull water out of the oil but I do not know if this is specifically glyc that has been used with water washing.

    My suggestions with this would be to make sure you mix the glyc and oil throughly. Give any treated oil a good long time to settle so the water has a chance to drop out and to then hot pan test the oil for water before you process. I would keep a sample of the oil before you can treat it so you can do some before and after water comparisons to see what is happening with it.

    If your oil does show water after mixing in the glyc, no biggie, just throw it in the dryer before you process it.
    If your oil does titrate on the high side, I think you will find the glyc treatment quite worthwhile.

    I have a couple of hundred litres of oil I picked up from restaurants which is not bad oil but very fatty. I might mix up a test batch of this oil and 20% glyc and see if it settles out any faster than a control sample.

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    Re: Adding some glycerine to WVO to lower ...

    Thank you Tilly and David.

    I'll think about this a while and try it when I have some water free glycerine.
    George

  7. #7
    David Guest

    Re: Adding some glycerine to WVO to lower ...

    I went and got plastic 2 bottles and put 1250Ml of fatty oil in one bottle and 250Ml of 5% water washed Glyc and 1L of oil in another bottle.

    I shook them both up well and sat them to rest in the sun.
    After just a few hours the glycerin has settled out and the oil is noticably lighter in colour and seems a little clearer than the pure oil sample.
    I'll see how they go in a week.

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    Re: Adding some glycerine to WVO to lower ...

    Quote Originally Posted by David View Post
    I went and got plastic 2 bottles and put 1250Ml of fatty oil in one bottle and 250Ml of 5% water washed Glyc and 1L of oil in another bottle.

    I shook them both up well and sat them to rest in the sun.
    After just a few hours the glycerin has settled out and the oil is noticably lighter in colour and seems a little clearer than the pure oil sample.
    I'll see how they go in a week.
    David,
    It would be interesting to titrate them both now to see if there is any initial difference in titration, and then do the one with glycerine again in a week to see if there is any further change in titration.
    George

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    Re: Adding some glycerine to WVO to lower ...

    The reduction of FFA in used oil mixed with biodiesel by-product was originally posted in the Goat industries Forum (UK) by HCII a couple of years ago. I subsequently discovered that it also dries the oil which was mixed in with it.
    It also seems to trap most of the high melting point oils from the used cooking oil also.

    Here is an experiment for you.
    Take a litre of your best (low titration) cooking oil, some fairly good (medium titration) oil, some poor (high titrating) oil and some oil with a lot of high melting point oil in it.
    Perform a titration of each oil. Record for later comparison.
    To each, add 200ml of biodiesel by-product. Stir in well.
    Allow to settle for 24 hours give or take a bit.
    Decant off as much of the liquid oil, as possible, from each batch and measure the volume of oil recovered. Record for later analysis.
    Titrate each batch, record for analysis.

    Here is my postulation:
    The volume of oil recovered will drop with increasing titration of the sample oil. - This is due to my belief that the remaining catalyst in the by-product will neutralise the FFA in the oil sample, producing soap.

    The end titration will be significantly less for the second titration, in each case. - Same reason as above

    The volume of oil recovered will drop proportionately with the % high melting point oils - I have experimented with this, and although I poured oil with ~25% high MP oil, only low MP oil was recovered.

    If you used by-product with methanol present, and have access to a GC, I believe that you would find that the initially low FFA oil has partially converted to biodiesel.

    If anyone wishes to perform these tests, please post the results here for all to see. I cannot, as I do not have accurate measurement abilities, or titration facility, plus I am too slack and make too many mistakes..

    Justifications on the biodiesel postulation:
    My calculations (for Titration + 5g/L NAOH and 100:22 oil:methanol biodiesel proportions)

    By-product: estimated 25% of oil used.

    Methanol content:
    - For stoichiometric methanol, in the biodiesel reaction, ~100:11 ratio is needed, thus ~11 litres of methanol (50%) could remain after the reaction, of 100L of oil, is complete.
    I guess at 1 litre in the biodiesel and 10 in the by-product layer.
    This would make the by-product approx 15:10 (glycerol,soaps, etc):methanol.

    Caustic content: The titration caustic is used converting FFA to soap, the catalyst portion is not consumed, thus for each 100L, there would be 500g NaOH remaining. This remains in the by-product layer.

    The by-product layer could contain 15L soap, glycerol, etc, 500g NaOH & 10L methanol.

    This proportion of NaOH and methanol could be used to convert approx 50 litres of used oil, titrating at 5g NaOH, to biodiesel. This ignores any NaOH/methanol holding effect of the glycerol.

    Can anyone put more accurate figures on my assumptions - I do not make biodiesel, so I can only postulate on this.

    Food for thought?

    Tony

  10. #10
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    Re: Adding some glycerine to WVO to lower ...

    Tilly, Tony and David,
    Questions of interest:
    • Does it lower titration and by how much?
    • Does it 'dry' the oil?
    • How much VO is left for processing?
    • Does it increase the final yield?
    • Does it remove high melt point oils?
    I will conduct some tests and post the results.
    If this proves an easy way of also removing suspended water from the oil, it could be a very useful and simple procedure to recommend as standard practice.


    George

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