hey guys iam new here and i have a few questions, so i have made some small test batches from new oil along with lightly used oil, so i started looking for used oil to try and find a good source, i got a some from a mexican resturant, and let it sit for a few weeks to let things settle a little.

so i titrated it and it was an average of 14 (i used sodium hydroxide for my titrant solution along for my batches).

so i did a test batch, i heated 500ml of the oil to about 135* mixed 9.5 grams of my sodium with 20% by volume pure methanol, mixed it in my blender for bio for 10 minutes poured it into a jar and let it settle.

after about an hour their was a clear line of separation then after more time i noteced their were some sort of strands of i dont even know what lol.

and later i looked again and i was in a jelly state and no longer fluid and now the bio (top portion) and glycerine (bottom) still have a solid line of separation but the glycerine is a tan color and cloudy not black anymore, and the bio diesel portion is cloudy with the strands.

what could this be? too much sodium hydroxide?

thanks in advance!!

A titration of 14 means you have some very, very bad oil there. You're going to have a hard time converting that stuff. I never deal with oil when it titrates over a 9, not worth the time and effort... but I have read that it's better to use more methanol, 25% or so, and more catalyst to get the rest of those fats out of there. You're going to sacrifice some fuel by making soap, but it's better than getting nothing out of it.

A titration of 14 means you are going to have to use 14 grams + base amount per litre of oil. Thats 14+5=19 grams of NaOH per litre of oil.

I wouldn't even bother with that oil. I'd be checking and double checking your titration. Then try titrating some new oil and see what you get. This will tell it your titration methods are working.

alright thanks guys ill look for a new source!

when you use NaOH the glycerin will solidify.... if you use KOH the glycerin will stay in a liquid state and you can compost the glycerin (after methanol recovery) without harming the soil.

If you titrate at 14 you have a lot of ffa's. You could consider doing an acid esterification with sulfuric acid and methanol before you do your trans esterification.


in my experience there is NO bad oil.

good luck!

Maybe for making a fuel but whomever let that vegetable oil get that bad sitting in a fryer is committing a crime within a restaurant. Or this oil's just been sitting out in the sun for way too long.

i did not know that KOH keeps it in liquid form thats good news, as for the acid i have learned a little about it but dont really understand whats going on.
could someone point me in a good direction to learn more about it
thanks

here is a good place to start with some basic knowledge dealing with high ffa feedstock. you can google Jon Van Gerpen he does lectures on the subject and will even do phone consultations... for a fee.



http://www.uiweb.uidaho.edu/bioenerg...ication/01.pdf

Prolly one of the best places to have a really good read up is this site.

I suggest you bookmark it as there are lots of referance material on this site.