I tried soap testing but it didn't work. Never got a blue color. Here's what I did:
Materials: 31.45 Muratic Acid
91% Isopropanol (ISP)
I made a 0.01N solution. The formula I used is as follows: 36.5gram-moles/31.45 g-m=1.16mL
So...I need 1.16 mL / Liter, but I chose to make a stock solution by adding 11.6 mL of acid to 988.4mL of distilled water which gave me a 0.1N solution.
Am I right so far??
I then took 90mL of distilled water and added 10mL of stock solution for my 0.01N test solution.
I then took 100mL of ISP then added the indicator (blue). It stayed yellow. I added 10mL of sample BD. It never turned blue.
I never added the acid solution because it never turned blue. I added more BD but it stayed yellow.
Before I go out and redo, was my math right for making a stock solution?
I'm guessing my ISP is a bit acidic. Can I add a few drops of my stock KOH solution until the ISP turns blue? Will this throw off my soap titration?
Since writing this I went back out and tried again doing what I asked. I added some KOH solution until it turned blue. I then conducted titration. It only took 4-5 drops to turn back to yellow. How "yellow" does it have to be before I stop adding HCl solution?
chirp, chirp, ribbit..chirp...
Sure is quite...everyone go out for the evening
before adding the biodiesel, add a few drops of phenolphthalein to the IPA. blank with KOH solution. Then add blue and bio.
How are you washing and drying?
I make 32 gallon batches and probably have 27 gallons of bd in the 55gal washdrum. I mist with probably 10 gallons x 3-4 times, add 10 gallons gently then bubble for few hours, then start hitting it hard with the nozzel then bubble wash. I usually wash 7-8 times. When my sample taken in an old dish soap bottle passes the shake test I quit. I dry in open top drum spraying and heating to 130F for 4-5 hours I have my last two samples in large mason jars, one made in Feb and one in March. Both are still crystal clear at room temperature. Even froze them in freezer and they thawed out and still nothing at the bottom of the jar....just curious, why?
So by adding phenol and blanking with KOH, your saying that just adding KOH to turn blue does not raise the pH enough before titrating soap? Do I blank with phenol until it just turns pink or do I try to get a bright pink? Do you remember the pH that blue turns yellow and phenol turns red?
IPA can go acidic with age. It's why we blank when we do our normal titration, that is to adjust the pH of the IPA. Blanking serves the same purpose. It makes sure the IPA is not acidic. You can also stick a pH strip in it to check it's pH and make sure it's close to 7.
I've never heard of bromophenol blue going acidic, so that means your biodiesel is acidic.
This is common, as in a big problem with ion exchange dry wash systems. They can make the fuel so acidic that it fails the ASTM "acid number test". But you water wash.
I'm not sure everyone will agree with this. It's a theory I've put together over time. Excessive bubble washing or hot drying either one can cause acidic biodiesel.
By excessive bubble washing, I mean bubble washing for total times greater than 48 hours. I think the air oxidizes the biodiesel causing it to go acidic.
The more likely culprit is the drying technique. Exposing hot biodiesel to air for extended periods (4+ hours) also causes the fuel to oxidize. Again this causes the fuel to go acidic.
Either process is like putting the aging process on fast forward.
Before we go any further, you need to make sure it's not your IPA going acidic that is causing the problem.
Are you sure? If it is stored properly, in a non reactive container, I'd wonder how this would happen, chemically.
I have seen some that is acid, even new samples, and figured it was just contamination.
I am pretty sure you are right. This is something I have seen a few times and suggested as a cause of high TAN in fuel dried with heat. I don't have personal tests to show this happening, but it stands to reason that if age can cause fuel to go acid, due to oxidation, then exposing BD to lots of air and heat could accelerate this process.
alcohols turn acidic with age. improper storage can accelerate it.
Jack needs to test his IPA to make sure the pH is not acidic as a first step. If it turns yellow when bromophenol blue is added, then it's most likely very acidic.
Are you reffing to becoming acetic acid?
Or, what is the mechanism?
How long does it take?
The IPA was a new bottle, 91%. I did blank with KOH and it took about 10 drops to turn and stay purplish. I just came in from testing for soap again. One sample that was done a couple of months ago, and one from the BD I've got bubble washing currently.
The old sample took 0.6mL X 320=192 ppm, and the current BD took 4.6mLx320 = 1572 ppm.
Ok, now I'm discouraged. I really thought the soap would have passed for the old sample. It "looks great", and nothing fell out over freezing thawing and sitting for two monhts With soap still in it, it probably would not pass the water test, huh?
I hate to think I'm tearing up my truck. I'm not quite sure what to do. Can I soap test before drying to ensure I pass the test??? This sure is using a lot of water....
Irock, it could something as simple as the amount of tme that you let it settle between washes.
Hookline, how long do you settle? To be honest with my job, I don't have a set regiment on how long I bubble, and let set. I usually drain in the morning, refill and bubble all day, then drain when I get home from work, refill and bubble all night. Sometimes I come home from lunch and drain, refill.
So I guess really it doesn't sit that long after bubbling.
usually 2 hrs, sometimes overnight. It allows the soapy water to drop fully thru the bio. Could be why you are needing so many washes.
OK, I took a sample of the BD I'm washing. I misted 4 times and added water with with no nozzel, bubbled, then added water with thumb over hose on last wash then started bubbling. After about 4 hours bubbling, I heated it up with drop in heater (120ish) and continued bubbling for another 9 hours. Just before I shut down the bubbling, I took a sample in glass jar. Looked crystal clear(amber). I sat it aside and this afternoon I tested for soap and it took .2mL. That should be good right? Since the BD sat in the drum undisturbed for about 15 hours, I took another sample and again, crystal clear. I tested for soap and again, .2mL.
Also, I have a 3/8" clear hose that I dip in the drum, crimp it and pull it out to see the bd/water transition...no soapy line at all, just clean bio, over clean water. Compared to first wash that had little mayo, no much though.
So, is it ok to test before drying? Is that how everyone else does it instead of waiting until drying to find out you still have soap?
It seems strange that I didn't wash as much as I've had to before. I'm going to do a shake em' up test and see how that comes out.
If I get a clear shake test, I go to drying
Yep. Me to.
Irokcj, I dry a small sample to titrate first. after a pass then I send to the dry tank.
It's what you learn after you know it all that counts.
That's a good ideal. I'll do that with the current batch since it's raining today and I won't be able to dry a large batch.
Irokcj5 Rereading this thread today, I couldn't find which inticator solution you use for your soap titrations. I believe ot should bromophenyl blue.
It's what you learn after you know it all that counts.
yep, that's it. I did a lot of soap testing this past weekend with what I believe was great success. Even though the bottle of IPA was new, it was a little acidic, at least according to the indicator.
I would blank the IPA with phenolphthalein to where it just began to turn purple/pink, then add oil and Blue indicator and then tritrate for soap.
How pure is the IPA you use?
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