I have over 700 gallons of glycerin stored and decided it was time to start making soap.I use KOH to react my Bio and want to make bar soap which I realize is a little tricky.I purchased the book "Making Biodiesel Soaps"and got busy.I have never seen a bar in person. The photos I've seen I assume were bars made from NAOH reacted Bio so I have nothing to compare my results to. After weeks of attempts I managed to make bars I was happy with and was also able to easily add other ingredients such as oatmeal and herbs that make bars that have impressed my friends.I have had nothing even close to a transparent result ,but this was of no concern.I decided to try and add some alcohol and sugar and the results blew me away.I got a beautiful,rock hard.dry to the touch, block of the dark transparent soap. I can not reproduce these results.I also have realized that the soap I had been making is technically defective. Everything is perfect until I add the Boric Acid. All attempts start with translucent results but turn to a foamy peanut butter. I thought this was normal but now I'm obseesed with finding the problem. Any tips would be greatly appreciated!
I made sodium soap, then added muriatic acid to the beaker the soap was in, heated a little , like magic an upper layer of liquid free fatty acids formed with a lower layer of water with sodium chloride (salt) in it. I'm assuming that is what it was, based on my chemistry education. The upper layer was white and opaque/ translucent. The free fatty acids in that case were not transparent like many other liquids are. Free fatty acids (ffas) are a weaker acid than hydrochloric acid (muriatic acid). HCl took the sodium away from the sodium soap leaving ffas and NaCl (sodium chloride) and water in the beaker. There was glycerine in there also. I dissolved potassium soap in distilled water then added distilled vinegar, I saw what was probably ffas float up to the surface of the vinegar/potassium soap aqueous solution. I think acetic acid (vinegar) is a stronger acid than long chain ffas derived from fats and oils, so it exchanged the potassium atom on the soap molecule with its hydrogen atom to produce sodium acetate and ffas. The lower density of the insoluble ffas caused them to float on the water solution. So Boric acid might be a stronger acid than your ffas in your potassium soap and be reacting to produce ffas and potassium borate, the ffas probably make your transparent soap opaque. I read today that too much boric acid in the neutralisation can cause cloudiness. Maybe this explains, in part why your soap changes its appearance
Thanks WesleyB for the very informative reply.I believe you have explained what is happening.One thing I should make clear is that I am only using KOH in the biodiesel process.I am using NAOH to make the soap. When I add the Boric Acid it is splitting the soap into two parts.I admit that in an attempt to speed the process I am adding an excess of NAOH to saponify the glycerin resulting in a PH of10.8. I then add enough Boric acid to drop this to 8. I think I may attempt to go for an amount of NAOH that brings the soap closer to my desired PH and use a weaker acid for fine tuning.I will also explore the idea that I may not be allowing enough time to fully saponify the glycerin with the NAOH.
The main issue I have with the soap I have been making is that although once cool it is solid,it is not very solid.It seems that it is only being held together by stickiness.The transparent soap is a single substance giving it much greater strength and resistance to humidity. Other qualities one might desire in a soap also seem to be better,although this may be subjective.. Is there a weaker acid that could be recommended? Citric acid produces similar results. Could the speed at which I neutralize be an issue? I have tried slowly adding and dumping it in .Maybe a super slow addition or greater dilution of the neutralizer would help. I appreciate any advice.My knowledge of chemistry is incomplete and funds are scarce. I am working to develop a complete biodiesel project for nonprofit charitable use.The ability to turn the glycerin into the highest quality product is a final missing part.This needs to be accomplished to receive funding.I've been broke and homeless,sleeping on the floor of my lab for eight months. I can not wait to get this done!
I got this off the internet, but I think it is true. "True soaps are composed of long chain fatty acid alkali salts with a pH of 9-10." I suggest you make soap and can use it for washing clothes rather than for use on washing people's skin. Maybe there's a misunderstanding? Soap isn't made from glycerol, it comes from the long chain fatty acid from fats and oils. A long chain fatty acid isn't glycerine it is a carboxylic acid which is something compleatly different. By adjusting your pH down to 8, with boric acid, I expect you are decomposing your true soap into free fatty acids. Can't you get your grant or funding by simply making true soap, for starters? You said you use NaOH (sodium hydroxide) in your soap making from the biodiesel lower layer product, but you use KOH (potassium hydroxide) as your catalyst for making biodiesel. I expect you have already made potassium soap. You could turn your potassium soap into free fatty acids, then react it with NaOH to make sodium soap if you want to. If you're using KOH as a catalyst to make biodiesel, where does the potassium go? It doesn't vanish, it's mostly in the lower layer that has glycerine in it. But is is not all glycerine. Thanks
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