Acidic Isopropyl in titration? - Diesel Forum

scbaguy · 12-13-2005, 08:10 PM

I've made 3 batches of BioDiesel. Jus the other day while makeingmy third, I did a blank titration. The Iso and turmeric titrated to 1.0

the last batch I made titrated to 1.7, and made lots of soap,and I lost alot in the washing. This latest batch (from the same oil) titrated to .7 after the blank titration of 1.0

I think this was the cause of the soap problem last batch.

My question is, is it normal for the Iso to go acidic that quick (3weeks), and can I still use it if I do a blank titration each time to adjust to it?

girlmark · 12-13-2005, 08:41 PM

I don't know what's normal as to storage- I haven't seen this happen- but I have found that some brands are more acidic than others. I'm not sure if this is due to shelf life.

in my experience:
red bottle Iso-Heet- usually very neutral
isopropyl version of Pyroil- I got some of this for a workshop this fall and it was a 1 on the blank titration- still usable but you definitely needed a blank titration
99% Longs Drugs rubbing alcohol- was fine until I got one acidic batch one day

but it's all usable, just do a blank every time to make it neutral.

Mark

h2odrx · 12-13-2005, 09:08 PM

I used the ph meter at work and when I added the isopropyl it went crazy? Jumped up to 12 the down 7 I finally gave up and will have to do something else?

bluenavigator · 12-14-2005, 10:45 PM

[ QUOTE ]
I used the ph meter at work and when I added the isopropyl it went crazy? Jumped up to 12 the down 7 I finally gave up and will have to do something else?

[/ QUOTE ]

Not sure about this isopropyl alcohol used with pH meter. In order to use pH meter, isopropyl alcohol isn't needed at all. Just need 0.1% NaOH solution. Add the NaOH solution to the oil sample, until the pH meter shows 7.0. Count how many mL of NaOH solution added to the sample.

Of course, 1 mL of oil in titration isn't enough for the pH meter to measure. So scale up alittle bit might be nut way to go.

I never try pH meter myself. I think that it is good idea to measure the isopropyl alcohol first. Then add 0.1% NaOH solution until pH meter hit 7.0. It should be stay that way. Just basic blank titration. If pH meter goes crazy, maybe it isn't good meter for titration. [img]/ubbthreads/images/graemlins/shrug.gif[/img]