Some people have asked about the potential toxicity of soap made from the glyc layer due to the fact that it is not likely that 100% of all the methanol is removed, and a small percentage may remain.

Although PURE methanol is quite toxic and potentially deadly, according to studies done there are acceptable low level exposures.

How the toxicity of an element is determined is by what is called the LD (Lethal Dose)rating. These LD ratings are listed on the MSDS of any given substance; on the MSDS for methanol it is listed as "ORL-HMN LDLO 428 mg kg" which means that taken orally in humans the lowest published lethal dose is 428 milligrams per Kg of body weight.

Methanol weighs 6.63lbs/USgal - 3.1Kg/3.78Lt. - 1.75Lbs/Lt -794gr/Lt.

A person weighing 200lbs (90.72Kg)would need to swallow 38910 milligrams (38.91gr / 49ml's) of pure methanol for it to be considered lethal in the lowest dosage test done.

As a comparison to put this in perspective The FDA states that 500milligrams daily is safe.

quote:

Refueling a fuel cell car with methanol will only give low-dose
exposures (23-38 ppm for a few minutes), with a small intake of 3 milligrams of methanol. This
is less than drinking a single can of diet soda containing 200 milligrams of aspartame which
would produce 20 milligrams of methanol in the body.

-
Methanol Health Effects

MSDS Methanol with Toxicity listings

Now conisder the extreme low levels that "might" be present in biodiesel glycerine that has been demethed using distillation and then spread out over x number of bars or x amount of liquid and the answer is a non issue.

You'll get heaps more by drinking a soda, and the soda you will consume in short order while one bar of soap will last you several washes.

So even if there IS trace elements of methanol present in the overall batch of demethed glycerine the amount actually reaching the end user via one bar or per usage in one bottle is so far below acceptable levels to be negligeable (which is basically what the chemistry prof I am associated with said).

I believe my math to be correct, but if someone would like to verify it, two heads (or more) are better than one.

As a point of reference, the concentrated syrop for Coca Cola, the soft drink, is a class 8 (corrosive) HazMat/Dangerous Goods and any tanker moving it over the road must be placcarded; however once dilluted at the bottling company into individual cans/bottles this once Hazzardous material is listed as safe, or GRAS
Generally RegardedAs Safe.

I hope that this will help any who are concerned about the safety factor of using the biodiesel glycerine layer for soap making.

**Obviously, this must be accompanied by the disclaimer that the distilling and removal of methanol from the glyc layer is the responsibility of the soap producer as is their verification of this information. It is offered here for educational purposes.**

I'm gonna make sure I save the link to this thread so I don't lose this calculation to reality!

As a bit of a bump and to continue along this same line somewhat:

Concern over the "purity" of the glycerine layer for soap making has also come up.

The oil should be filtered prior to reaction if one intends to make soap from the glyc layer afterwards. This not only helps the reaction but gives a glycerine that is cleaner.

The oil itself is subjected to a caustic alcohol bath at 130F/55C for anywhere from one to two hours.This in itself deals with a great deal of the potential bacterial residuals, but it doesn't end there. Once the glycerine is removed form the tank the methanol has to be removed / recovered. This is best and most environmentally responsibly done with a condenser hooked up to a distilling tank.

Methanol evaporates at 148.5F/65C, but in order to get it all out the pot temperature must go considerably higher than this. In my case I hold the head temp at 150-152F for several hours and the pot temperature, or temperature of the glycerine itself, reaches and holds 130C/266F during this time. It is kept there until all I get is a pittle coming out of the condensing coil.

To contrast this, an otoclav, used to sterilise medical equipment, uses steam at 130C for a period of 3-15 MINUTES and the items are considered sterilised, and for the elimination of prions a temp of 121-132C for an hour or 18 minutes at 134C.

Sterilisation (Microbiology)

Therefore, it is reasonable to accept that the glycerine layer, once processed and distilled, has been ridded of any potential for bacterial contamination. The methanol question has been dealt with above.

HTH

What else could be in the glycerine assuming we allow it to settle and filter it prior to making biodiesel? typically our oil titrates lower than 8.
What on the off chance that someone uses some drain cleaner and that gets in the oil. Would it settle out with any water or debris? Would it be rendered inactive from the caustic bath?

Drain cleaner ? As in NaOH ? It depends on how much was tossed into it.Toss in enough and you will saponify the lot.Mucho soap,zero biodiesel.

If it is liquid drain opener there would be a significant amount of water in it as well and that would just exaserbate the saponification.
What you would likely have is oil that has a bunch of soap in it. Great if your plan is to turn it ALL into soap but maybe not so great if you are planning on making biodiesel from it first.

Bump (again)

Thanks Legal,

I have had concerns about methanol remaining in my gly then soap. Your replies on both threads is appreciated.

Eddie

recalculating reality! you also need to factor in the amount of water being added to the glc. when makeing the soap. remember that methanol is water soluable.

quote:

recalculating reality! you also need to factor in the amount of water being added to the glc. when makeing the soap. remember that methanol is water soluable.

Exactly ! The fact is that once you have demethed to a dribble at 266F pot temp and 150-152F head temp for several hours what you have is a safe product that is for all purposes sterilised of all possible bacteria and animal prions as well.

Taken that the amount of potential methanol remaining in the glycerine after all that and diluting that down through the soap making process even further what you get as a per useage value is negligeable, in fact much much lower than swallowing a can of diet soft drink or commercially available juice.

Of course the onus of responsibility for safe production rests wholly on the shoulders of the soap maker, but being forarmed with information on how to make it so can't do anything but help.

I am wondering if there has been any testing to try to "bleach" this bd glycerin.Maybe with exposure to hydrogen peroxide or something?

quote:

Originally posted by angelhair:
I am wondering if there has been any testing to try to "bleach" this bd glycerin.Maybe with exposure to hydrogen peroxide or something?

Asked and answered before but here goes: Taken from the MSDS on Hydrogen Peroxide 30% solution

quote:

Forms potentially explosive compounds with ketones, ethers, alcohols, hydrazine, glycerine,...

Before adding any substance to a concentrated glycerine layer you should always check the MSDS on it to see if there are any incompatibility issues.

Legal

Would it be better to use distilled water as to tap water in the soap making process?

joshin

That would depend on the purity of your tap water. For most tap will be fine, although the purists/traditionalists prefer distilled as there are no "impurities" in it; but then these are the same people who don't hesitate to put all kinds of chemical enhancers and additives too, so go figure.