Glycerol composition.

[WesleyB Donating Member Find all posts View Profile Close WesleyB]

Re: Glycerol composition.

I used calcium oxide and potassium hydroxide in the methanol. I didn't remove the calcium oxide and calcium dihydroxide prior to doing a room temperature transesterification reaction on new corn oil. I got glycerol fall out but an excess of strong base. In the soap test I used up all my weak hydrochloric acid testing for soap. Removing the finely divided calcium hydroxide and calcium oxide from the methanol seems to be correct. My room temperature biodiesel product is transparent yellow. I expect calcium soap is present (that's bad).

[smithw Senior Member Find all posts View Profile Close smithw]

Re: Glycerol composition.

Your bio sounds good. You do have to watch getting some unreacted CaO into the methoxide. As you say it is very easy to disturb it. Did you notice any reduction in your glycerol volume.

I got a little less glycerol, I can get as much as 120 liters, this time I got 90 liters which is on the low end of what i usually get.

[smithy Senior Member Find all posts View Profile Close smithy]

Re: Glycerol composition.

That reduction in glycerol is good. Less glyc = more yield, well done.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Glycerol composition.

Less byproduct may indicate greater yield, but what about quality?
Byproduct = Glycerol, soaps, residual methanol, unused caustic, water (from the reaction) and other contaminants in the oil.
What has been reduced in your "glycerol"? to reduce the volume you measured from this batch?

[smithw Senior Member Find all posts View Profile Close smithw]

Re: Glycerol composition.

Hi Tony
I got a little more bio than I usually get about 20-30 liters, I was more concerned about the 3/27 test come out murky. Even after 2 days it still looks the same, no drop out. The bio itself look really good.
Im having a think about where to go from here.
My Bio book still hasn't turned up

[smithy Senior Member Find all posts View Profile Close smithy]

Re: Glycerol composition.

Tony, the only contaminate that would adversely affect the bio using methoxide dried with cement or CaO would be calcuim soap. This will only be present if some cement/CaO fines have found their way into the methoxide added to the oil.

The reduction in glycerol volume is an indication that less soap has been produced. If glycerol is cracked with conc sulphuric the top FFA layer formed is an indication of the original soap content of the glycerol, which is on average in the order of 35% by volume. Do this test with glycerol from dry oil and methoxide ex the imisides drying method and the FFA layer is virtually non existant.

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Glycerol composition.

Hi smithy,

Tilly, the CaO amount is contained under the heading 'clinker' it will be similar to the 63% I posted above, otherwise any buildings made from cement with the CaO content you suggested would fall down!

You seem confused.
We are concerned with the amount of "free CaO" available in our bag of finest Grey cement, NOT the amount of CaO that is used to produce the cement.

Burning in a kiln – formation of cement clinker

Solid state reaction zone (900˚ - 1300˚)
CaO and reactive silica combine to form small crystals of belite, one of the four main cement minerals.

Clinkering zone (1300˚C – 1550˚C)
Inside the liquid phase, Alite forms by reaction between Belite crystals and CaO.
Crystals of solid Alite grow within the liquid, while crystals of Belite formed earlier decrease in number but grow in size.
The clinkering process is complete when all of silica is in the Alite and Belite crystals and the amount of free lime (CaO) is reduced to a minimal level (<1%).

Chemical composition of clinker
The cement clinker formed has the following typical composition:

Compound	Formula	Shorthand form	% by weight1
Tricalcium aluminate	Ca3Al2O6	C3A	10
Tetracalcium aluminoferrite	Ca4Al2Fe2O10	C4AF	8
Belite or dicalcium silicate	Ca2SiO5	C2S	20
Alite or tricalcium silicate	Ca3SiO4	C3S	55
Sodium oxide	Na2O	N	) )Up to 2
Potassium oxide	K2O	K
Gypsum	CaSO4.2H2O	CSH2	5

Think of making glass
While you start out with mostly sand in the furnace, there is very little sand left when you finish

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Glycerol composition.

Hi Tony,

Less byproduct may indicate greater yield, but what about quality?
Byproduct = Glycerol, soaps, residual methanol, unused caustic, water (from the reaction) and other contaminants in the oil.
What has been reduced in your "glycerol"? to reduce the volume you measured from this batch?

The problem is the continual pretending that the glycerol prewash is not a stage of reaction.
When the first stage of reaction performed is a glycerol pre wash where neither the amount of chemicals used in this first stage is measured or known and the byproduct/ glycerol (soap and glyerine) produced during this first stage are also unknown, the amount of byproduct/ glycerol produced in subsequent stages has no meaning.

Also, because there is biodiesel bound with the glycerol used to perform this first stage and an unknown amount of this biodiesel is released into the reactor, yield is not measurable.

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Glycerol composition.

Hi smithy,

The reduction in glycerol volume is an indication that less soap has been produced. If glycerol is cracked with conc sulphuric the top FFA layer formed is an indication of the original soap content of the glycerol, which is on average in the order of 35% by volume.

The problem here is that you pretend the glycerol pre-wash is not a stage of reaction and you do not include the soap or the glyceine produced during this first stage reaction when you do your testing.

Have another look at the test results DavidS reported to refresh your memory of the difference between dried and non-dried methoxide

HINT: No matter what magical procedure you use, FFA's will NOT be converted into biodiesel in a Base only reaction

Smithy, you have still not explained how you achieve a full conversion in a single stage reaction on WVO using just 12% methanol.
I am sure all the people who you claim are reluctant to join in this discussion for fear of being humiliated are desperate to know how you achieve this seemingly impossible feat.
Please tell us how you do this.

"I appreciate your effort here but you consistently get results that no one else can achieve due to unknown circumstances, because of this your results dont hold much weight."

[smithy Senior Member Find all posts View Profile Close smithy]

Re: Glycerol composition.

I'll handle some of the info posted by Tilly in due course . Too busy getting ready for Christmas Day at the moment, but for now:

Clinker Composition

In cement chemistry, chemical analyses are normally given in oxide form - a typical example of an analysis follows:

Typical clinker analysis (oxide weight%).
SiO2	Al2O3	Fe2O3	CaO	MgO	K2O	Na2O	SO3	LOI	IR	Total
21.5	5.2	2.8	66.6	1.0	0.6	0.2	1.0	1.5	0.5	98.9
Free lime = 1.0% CaO Balance is typically due to small amounts of oxides of titanium, manganese, phosphorus and chromium.

From the chemical analysis, the quantity of each of the four main minerals can be calculated using the 'Bogue' calculation (click on the link below for more information.)

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Glycerol composition.

Hi smithy,

Smithy posted:
Free lime = 1.0% CaO

1% free CaO sounds about right- perhaps a tad higher than desired but close enough.
As I mentioned in an earlier post in this thread, the MSDS for Grey cement lists the CaO content as 0- 1%
"The free CaO (often called the “free lime”) is the amount of calcium oxide present as CaO, that is, not bound into the cement minerals"

It is good to see that you agreeing with me

The great majority of CaO used to produce Cement Clinker is "used up" during the sintering process to produce Alite and Belite so there is virtually no CaO available to remove water during the drying of the methoxide.

Merry Christmas

[DavidS Junior Member Find all posts View Profile Close DavidS]

Re: Glycerol composition.

Hi Tilly and Merry Christmas to you.


Even at only 1% free CaO, there was a difference in the tests I ran previously. Perhaps I should do it again using CaO instead of the cement as the "drying agent". I have some CaO in a sealed tub.


Best wishes


David

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Glycerol composition.

Hi DavidS,

Even at only 1% free CaO, there was a difference in the tests I ran previously. Perhaps I should do it again using CaO instead of the cement as the "drying agent". I have some CaO in a sealed tub.

Yes, there was a difference.
Because there is virtually no free CaO in cement to do the drying, it is very likely that one of the minerals produced during the sintering procedure is actually removing the water.
As I recall, I also pointed out the lack of free CaO in cement to the author of this drying procedure and his reply was that it did not really matter what it was in the cement that was removing the water as long as it did not also remove methanol.

My guess is that the difference in the batches was mostly because the drying procedure removed the 10% water in the KOH and not so much the removal of the small amount of water produced making Methoxide.

Water is only produced when you mix KOH or NaOH with methanol if Methoxide is actually produced
The chemist Neutral said that he thought there is actually very little methoxide produced when you mix KOH or NaOH with methanol and what we actually have is mostly just KOH or NaOH dissolved in methanol with a small amount of methoxide produced. Dissolving KOH or NaOH in methanol does not produce water, it is the production of methoxide that produces water.

It would be interesting to see what happens if NaOH, which typically contains virtually no water, were used in the comparison test instead of KOH

Merry Christmas to you too!

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Glycerol composition.

Hi everyone,
Before Christmas we were discussing caustic stripping and in particular, the instructions in Paul Martin's book "Grown Fuel Biodiesel in practice"
At the time I did question whether the instructions posted were accurate because they seemed to require a substantial excess of KOH.
So I sent Paul an email querying the instructions as presented to this forum and I went to the local Paradise library and arranged for the book in question to be sent from the Gold Coast on an inter library loan.
So far, Paul has not responded to my email.
The book arrived at our library yesterday. The following are the instructions posted on page 18 of the 2008 edition of the book

Removing Free Fatty Acids (FFAs)

Only try this when you have been making biodiesel successfully for many months. It is a process that needs to be adjusted to suit, it can help or create a mess if you are not careful
FFAs can be neutralised first to improve yield. Try stripping them from feedstock by adding a mixture of potassium hydroxide (KOH) and water to the feed stock.
1. Determine the amount of KOH to add by titrating (See page 20) This time however, use the following formula:
KOH in grams= (3.5+Y) x feedstock volume in litres.
2. Measure out 40ml of water for every litre of feedstock and bring to the boil
3. Add the required amount of KOH to the water.
4. Ensure the feedstock is heated to 40C, then mix in the water/KOH mixture.
5. Allow soaps to settle overnight.
6 Titrate again to observe a reduction in catalyst needed for the batch.


I still have serious doubts about these instructions- especially as it seems to require the addition of the KOH to BOILING water!

[smithw Senior Member Find all posts View Profile Close smithw]

Re: Glycerol composition.

That is interesting, I have the 2006 edition 3 and everything is the same except you add NaOH to the boiling water. I still have not received my new book, and he hasn't responded to my email either. In practice I use hot water out of the safety valve on the hot water cylinder so around 60C and it works just fine.
I'm a bit hesitant to do another batch of cement diesel as I still don't know what that white stuff is that drops out with the 10/90 test.It did work well though and I did get a little more bio and a little less glysterne