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World Famous Dr Pepper Technique (Pat Pend)
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Hello Andy

Are you using NaOH or KOH in your reaction?

In my experience clear Gels are soap caused when reacting with NaOH.
If you use NaOH in the reaction, When you evaporate the methanol out of biodiesel, soap will often settle out on top in a thin layer as you have described it.

If you are following the World Famous Dr Pepper Technique directions for making a litre of high conversion biodiesel from new oil (5g NaOH, 250ml methanol, react at 55deg C, an initial 40 good shakes followed by four more 5 second shakes over the hour) you should be making very high conversion biodiesel.
If you reprocess it using 4g NaOH/KOH and 100 ml methanol you will make lots of soap. Be aware that what is called the glycerine layer actually contains a LOT of methanol, probably 50% methanol in the first reaction when processing new oil.
The "Glycerine" layer of the second stage will likely be mostly methanol and soap. So the size of the methanol layer produced in the second stage is mostly dependant on how much methanol is used in the reaction and not an indication of how far the first stage reaction went.
There is a Hyperlink to the World Famous Dr Pepper Wash Technique (Pat Pend) in the World Famous Dr Pepper Technique (Pat Pend)
The fact that you are only achieving a yield of 200ml per litre of oil reacted suggests that you are making a lot of soap in the re-process. In my experience that is exactly what happens when you reprocess very high conversion biodiesel with 1g NaOH mixed into 50ml methanol.

All that is white is not soap.

The "Shake-um up" test has been shown over and over to be a meaningless test for quality. It is fine for showing the presence of soap.
Soap is at least as likely to cause an emulsion as an incomplete reaction. In my experience, if you use hard water for the test most biodiesel passes this test. If you use soft water most biodiesel fails this test.

I would have to do some tests before I put any faith in the shake and look for bubbles quality test.






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
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Tilly,

Had a detailed reply and more input but,,,,

this is my third try at replying. I spent over an hour getting bumped off the reply page. don't know what's happening so I'll make this quick.

I'm going to go over the entire thread and do some more research. I have no doubt that temperature is my problem. We go down to 10C in the shop on occasion.

I'm of the mind that if we use more NaOH and let the mix settle overnight at warm temps we might have better results. Will test that premise.

Many, many thanks for your input and in fact, for starting this thread. We learn by reading, but mostly by doing.
 
Registered: September 10, 2006Reply With QuoteReport This Post
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Tilly,

As I understand it, the purpose of this thread was to offer a simple way that the newcomer to the making of Biodiesel can gain some insight and experience.

THAT you have accomplished in spades. And maybe this has been covered but we've done some experimenting and maybe we can shed some more light on problems some might have encountered.

First, I made up a batch of Sodium Methoxide, 250ml methanol and 5g lye. This was stirred and mixed for an hour to make sure that ALL of the lye was dissolved.

Then we added this mix to 1 litre of virgin, soy/canola oil, first heated to 70 degrees. Yes, a little hot but we lose some in the transfer.

This was given 100 violent shakes. The bottle was then set into a small tub of HOT water from the tap. Every fifteen minutes, 20 additional, vigorous shakes were applied six times.

Then the mix was allowed to settle in a special rig I made. This is pictured in the attachment.

This is a commercial product that is used to meter exact quantities of any sort of liquid. The cap fits any typical plastic gallon jug. It also comes with an adaptor that allows it to be secured to your common, 2 litre, soft drink bottle. It also fits a number of bottled water, bottles.

Included is a twist valve and a 20", clear, plastic tube with a stopper at the end. This was trimmed to three inches and an adaptor was applied to the open end carrying a short length of neoprene tubing. This is stoppered by a common paper clip.

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Registered: September 10, 2006Reply With QuoteReport This Post
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The way this is meant to work is to isolate the "glycerin" that has settled from the good stuff above by using the valve. Once the sight glass is isolated, the bottle can then be set upright, the cap taken off and the fuel then transfered to a wash bottle.

Stoppering with a thumb while draining can work but perhaps some material that we don't want going back into the fuel is being left behind.

The next picture illustrates good conversion and settling of the "glycerin".

It doesn't look like a lot but this was allowed to settle for three hours. However, there IS a quantity of material contained in the valve and clear tubing.

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Registered: September 10, 2006Reply With QuoteReport This Post
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The bulk of the settled material was drained out but stopped at where we could see some left, at the bottom of the clear tube. The level was marked as illustrated.

The main valve was left open and the device was tapped with a piece of dowel to dislodge any glycerine that my have been trapped therein. This was then allowed to sit for another three hours. No additonal glycerin settled out after that space of time.

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Registered: September 10, 2006Reply With QuoteReport This Post
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HOWEVER, we noticed small globs of something, attached to the sloped sides of the bottle. What could they be? By tapping the sides of the bottle, we could dislodge these bits and they would promptly start sinking.

After ten minutes of tapping and observing, we found we had accumulated more glycerin. That is illustrated by the second mark.

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Registered: September 10, 2006Reply With QuoteReport This Post



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These blobs are shown here.

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Registered: September 10, 2006Reply With QuoteReport This Post
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And here.

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Registered: September 10, 2006Reply With QuoteReport This Post
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OK, if those bits of glycerine were collecting on the sides, it would be reasonable to assume that there was still a quantity of glycerine in suspension.

So the rig was allowed to sit in the heated portion of the shop overnight. The heat was turned up and for 24 hours, our experiment was allowed to bask in 80 degree F heat.

The result, without any tapping to dislodge any material, can be seen below.

Entirely on its own, an extra 1.125 inches of material had settled. Adding the 3/8" inch that represents the first mark, we have 1.5" inches of additional glycerin settling out. That is, without any additional agitation to dislodge any of the globs that were now visible on the sides of the bottle.

Grabbing the bottle and twisting back and forth created a swirling of the mix and this action cleaned off most of the globs. They quickly settled and topped off the sight tube.

The clear tube's ID is 1/2" so my math tells me that overnight, we had an additional 24 ml of glycerine settling out, on its own, after 24 hours.

This rig is going to be allowed to sit for as long as it takes until no more glycerin makes its way to the sight tube.

Then we'll do the water and meth test.

Then we'll do the Dr Pepper wash and see what happens using the same rig.

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Registered: September 10, 2006Reply With QuoteReport This Post
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I'm inclined to think that the cool conditions in my external shop created some of the early problems I encountered. Some nights it can get down to 40F.

So we'll see what we get, in the end.

Meanwhile, about washing. Here we have the results of a vigorous shake of good Biodiesel with distilled water. This is about a minute after a 20X shake.

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Registered: September 10, 2006Reply With QuoteReport This Post
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And here's the result after 10 minutes. Crystal clear, colourless water with no, paper thin, white line of scum. Absolutely clean, Biodiesel. The bubbles you see on magnification are air bubbles. They rise and eventually, are totally dissipated.

Doing the meth test has the fuel go instantly into solution with another crystal clear, colourless result. In fact, a 50/50 mix was tried and still, the biodiesel goes into solution perfectly.

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Registered: September 10, 2006Reply With QuoteReport This Post
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About the boil test. A recent batch of good fuel that passed the water and meth test did not come to a nice boil. Yes, this time I did it outside, on a hot plate, with a fire extinguisher handy.

Also, the shake and bubble test. Some batches of good fuel make lots of bubbles, others, not so much. Both the coconut and the olive fuel don't any make bubbles at all. Both have a notably lower viscosity than any of my other samples and both boil quite readily.

So again, it may simply be the type of oil used to make your fuel in any of this.

Once we have a repeatable procedure for making good fuel on the first pass, we'll be experimenting with using various types of oil.
 
Registered: September 10, 2006Reply With QuoteReport This Post



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About haziness and drying. A week if sitting in an open container would not allow the fuel to clarify. Yes, cool, basement shop. So I took a batch to the hot plate and heated. On this sample, I also did a boil test. Well, this good fuel, that passed the water and meth test, would NOT boil. Not even after it started to smoke.

What happened was that it turned a nice golden, more like orange colour. It didn't form any froth but I did get a clear, gel like material form.

That was filtered out as can be seen below. The filter is just a funnel with some fine, silk material as the filtering medium.

The gel was clear, but interestingly, the fuel lost its orange colour.

It's now clear and passes both the water and meth test.

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Registered: September 10, 2006Reply With QuoteReport This Post
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But before boiling, this fuel that had been allowed to sit for a week, was transfered to another bottle and was filtered as a matter of course. The result was that the silk allowed the fuel to pass but water, in small globs, was held back. Surface tension action, I presume.

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Registered: September 10, 2006Reply With QuoteReport This Post
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So to avoid the need for heating to clarify, maybe all we need to do is to allow the final wash to settle longer. A week? Two weeks?

With that in mind, we made up some adaptors for Dr. Pepper bottles as shown. These will attach to 6", clear vinyl tubing with a stopper on the end.

The tubing acts as a sight glass. As water collects, we drain and note the water level. When no more water accumulates, we assume a dry fuel. That will be tested.

Waiting till all the water comes out of suspension is much more energy efficient than having to heat it up.

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Registered: September 10, 2006Reply With QuoteReport This Post
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And Finally. As you say, reprocessing as I've been doing it, appears to make soap out of a lot of perfectly good Biodiesel.

Some early batches pass the water test easily but don't pass the meth test.

What would you recommend to salvage this fuel?
 
Registered: September 10, 2006Reply With QuoteReport This Post
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OK, this is day three of our test of the Dr. Pepper method of making Biodiesel.

As related, we have followed the instructions to the letter. Plus, we have ensured that the temperature of the initial reaction was a tad higher than required. I'm assuming that this wouldn't hurt, could only help.

OK, after draining off ALL of the glycerin mix that had settled into the sight tube, we let the jug sit in the very warm shop overnight.

The result was that more material settled. AND, we have more of the globs of Glycerin stuck to the sides of the bottle. That is, the sloped sides. The vertical sides don't allow these to collect.

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Registered: September 10, 2006Reply With QuoteReport This Post
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Without disturbing the material settled on to the sloping sides of the jug, we drained off the glycerin mix evident in the last picture.

By this time we had noted that three days of settling had allowed the upper part of the jug to clarify just a bit more than the lower section.

On the chance that there was a difference between the top of the mix and the bottom, we drew off a bit of the fuel from the bottom end.

Then we punched a very small hole an inch below the "water line" And squeezed some fuel from the top portion.

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In some quarters, it is asserted that doing a water test on unwashed fuel gives an indicator of the quality of conversion.

So we did that test with both samples.

Here we see the samples one minute after shaking.

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One hour later.

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