Jim,
I think your math is right.
You would have to use a different indicator solution though.
Phenolphthalein will decolorize below pH of 8.0.
We would want one that changes color at neutral or below. Ex:
Phenol Red turns yellow below pH of 6.8 Swimming pool test kits)
Bromthymol Blue turns yellow below pH of 6.0
I don't know how elaborate we have to get w. the setup. Diluting the
glycerine might make it easier to see color change in the indicator. Of
course we might be barking up the wrong tree entirely.
Todd describes a reliable procedure for determining the amount of acid
needed to split the glycerine (see JTF "Separating Glycerine").
I've been putting off experimenting for two reasons:
1. I don't have a pH meter, but now you've gone and suggested using
indicators .... so much for that excuse.
2. I have a simple, reliable procedure in place, that works well w. the
glycerine mix I produce.My WVO is very consistent: titrates between 1.0 &
1.5 g lye/L. I start at the low end of the range Todd suggested that I use,
and gradually increase acid until the mix splits.
It's raining here. Maybe I'll try your plan and see what happens.
Tom
----- Original Message -----
From: "JJJN" <[EMAIL PROTECTED]>
To: <Biofuel@sustainablelists.org>
Sent: Monday, May 15, 2006 11:47 PM
Subject: Re: [Biofuel] Separating Glycerine
> Tom ,
> I have been wondering about this too, so far I thought I would try the
> steps below but i would rather here where i went wrong in my thinking
> first.
>
> Lets say we have 10 Liters of Cocktail well mixed and we take 10 ml out
> and add it to 100 ml of Ph neutral water with phenolthalene (sp) mixed
> in. Now lets say we mix this up good and we should be seeing some good
> pink water. Now lets take our acid and dilute it by 50% with water. Now
> if we take an eye dropper that allows to drop 1 ml at a time to the mix.
> lets say we drop 10, 1 ml drops and it goes clear - no pink. Now I have
> never been a math wizard so correct me when I blunder forth here... 5ml
> acid neutralized 10 ml of cocktail to ph 7 or past so 5 liters of acid
> would do the trick in this example ( I must have picked some terrible
> numbers for illustration purposes),
>
> Ok how bad did I muss up and where did I?
>
> Help Too!
> Jim
>
> Thomas Kelly wrote:
>
>> Hello to all,
>> The short version:
>> 1. To split the glycerine cocktail must one merely neutralize the
>> NaOH/KOH used to produce it or is it necessary to go beyond neutral,
>> to acid?
>> 2. If it must be acidic,
>> if one knows how much H3PO4 it takes to neutralize the mix, can
>> one predict how much more H3PO4 it will take, to get the split?
>>
>> The long version:
>> On 4/10/06 Todd Swearingen, in a post entitled "Re: Separating
>> Glycerine" suggested that I would need to add 510 - 590 ml of 85%
>> phosphoric acid to each cubie (4.5 gal/17.7L plastic container) of
>> glycerine cocktail to achieve a split.
>> Sure enough, when I added 540 ml (lowest) - 580ml (highest) of
>> 85% H3PO4 to the next cubies of glycerine mix I got separation into
>> mineral precip, crude glycerine, & free fatty acids.
>> I've been wondering ever since how he was able to make the
>> calculation/prediction .... or is he just a good guesser?
>>
>> On 12/02/05 Bioclaire Nederland described how to calculate the
>> amount of H3PO4 to add for separation if one knew the amount of NaOH
>> used to process the WVO that yielded the Glycerine cocktail. (See
>> "separating Glycerine" & "separating Glycerine Mistake!").
>> The explanation is based on the equation for neutralizing NaOH
>> using H3PO4.
>> H3PO4 + 3NaOH ------> Na3PO4 + 3H2O
>> 1 Mole (98g) of H3PO4 will neutralize 3Moles (120g) NaOH
>>
>> If one knows how much NaOH (or KOH) was used in the batch(es)
>> that produced the Glycerine cocktail it should be possible to
>> calculate how much H3PO4 it would take to neutralize (and split?) the
>> mix.
>>
>> Here is where the problem, and questions come in:
>> The Glycerine mix I was using (4.5 gal/17.7L) containers each
>> came from two 76L batches (152 L WVO, total).
>> The oil I used for these batches titrated at 1.0 - 1.5 g NaOH/L of
>> WVO. (684 - 760 g of NaOH)
>> Adjusting for 85% H3PO4 (115g of 85% H3PO4 would contain the
>> 98g - i.e. 1M.- of H3PO4) and using the density of 85% H3PO4 (~
>> 1.59g/ml), that I should only need 460ml of the 85% H3PO4 to
>> neutralize the lye used to process the oil.
>> Not all of the lye is in the glycerine cocktail. Some is in the
>> BD. I use 0.20 ml H3PO4/L of oil processed when I do my first wash
>> (15ml/76L batch or 30ml for two batches). This results in wash water
>> very close to neutral suggesting to me that approximately 50 g of the
>> lye used to process the WVO comes out in the BD, not in the Glyc. mix.
>> The 710g of lye that is in the glyc. mix should only take about 430 ml
>> of the 85% H3PO4 to be neutralized.
>>
>> None of the cubies would separate w less than 540ml of the 85%
>> H3PO4. This suggests that it takes more than merely neutralizing the
>> glycerine mix to get it to split.
>> (Answer to Ques #1?)
>> Note: I'm doing a lot of this in my basement or in a shed out
>> back, not a lab.
>> So how did you do it Todd? Neutralize + 20%?
>> If it's a secret, include the word iguana anywhere in your
>> response and I'll drop the subject.
>> Still puzzled
>> Tom
>>
>>
>>
>>
>>------------------------------------------------------------------------
>>
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>>
>
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