I would like to start a thread for the recipes that people use for reducing high ffa oils by means of sulfuric acid. By high ffa I mean titratations in double digits. I personally have not found a consistently reliable method for my oil. Titrations for me range from 15-30.

Please list your recipe's formula, the starting titration range that you have had CONSISTENT success with, as well as detailed procedure steps (reaction time, temp, water content, number of stages, drain/no drain, titration curves, yield, etc).

The acid/base theory can be confusing and has a lot of gray area and it seems to me that no one formula works for every situation. Let's help each other out to find an "industry standard" that we can all utilize. This will make more wvo sources available as suppliers become harder to find.

Please try to be as specific as possible.

Thanks

Travis,
I'm working an article for the CBT about Acid/Base processing.

I would guess I have made more than 50 batches( 60 gallons of oil at a time) using my formula. only the last 2 I have tried draining.
the yield is usually slight lower than if the started at 3 titration. Its still way higher than using base only stages

please PM me if you have questions or problems. I'll try my best to help. Also I would like some feed back if you use my method. things starting titration, ending titration, did to drain and retitrate? the usual technical stuff.

-dkenny

dkenny, you probably have as much experience with acid base as anyone. I am now using sodium methylate and it seems to work well except that I have residual water left over from the acid stage. The methylate does not tolerate water well and the reactions are not going to completion. I have tried to drain it off but frequently the water/methanol phase resides on top as it does not settle out. If this phase resides in a closed processor, how does one remove before beginning the base stage? It could be boiled off, although that is not ideal. It could be drained and settled? It could be mixed dosed with grits and the grits removed in filtration. If demethed glycerol were added to the process between stages, would the water and methanol remaining naturally migrate into the glycerol for easy removal? Could the methanol used in the acid stage be reduced to a level where little excess would remain at the end of the stage to bind with the water, allowing the water to drop out? I realize you may be using a different catalyst, however I would appreciate your perspective on the above. Thanks, Jack

If you want the methanol phase to settle either reduce the methanol amount or increase the acid amount. Set up a spreadsheet and you can play with the amounts until you get a phase with a density of 0.95 or more. Make sure that you account for the methanol that gets used up as the FFA are converted into biodiesel. Don't forget the water contribution to the phase, about 1/15 of the FFA mass.

jackmac,
thanks..
your touching on one of the biggest problems in homebrew acid/base processing. I think by restricting the amount of methanol( it floats on oil) it possible to get water to sink..so to speak.

I have been recently talking with GM about this issue and we float(sank) several ideas on how to get this to happen if it doesn't happen on its own.

I think the amount of methanol used in relation to the %FFA will help determine whether the layer sinks or floats.

questions for you:
what titration are you working with?
what percent ( by oil volume) are you using in the acid stage?
how much acid are you using per liter?
is the acid quantity base on titration?

I've heard rumors of some of related information coming on future publications but I don't know details.

fyi. from a limited number of samples I seeing that the amount to drain( I know, I'm one against draining) is about 1/2 the amount of methanol used in the acid stage.

-dkenny

quote:

Originally posted by dkenny:
jackmac,
thanks..
your touching on one of the biggest problems in homebrew acid/base processing. I think by restricting the amount of methanol( it floats on oil) it possible to get water to sink..so to speak.

I have been recently talking with GM about this issue and we float(sank) several ideas on how to get this to happen if it doesn't happen on its own.

I think the amount of methanol used in relation to the %FFA will help determine whether the layer sinks or floats.

questions for you:
what titration are you working with?
6.0
what percent ( by oil volume) are you using in the acid stage? I have been using 8% methanol
how much acid are you using per liter? 2ml/liter
is the acid quantity base on titration? I used your formula but the FFA reduction was taking forever. 2ml/liter has that reduction to 2.75-3+ within 12 hours.

I've heard rumors of some of related information coming on future publications but I don't know details.

fyi. from a limited number of samples I seeing that the amount to drain( I know, I'm one against draining) is about 1/2 the amount of methanol used in the acid stage.

-dkenny

Thanks, I have not tried your formula since beginning the methylate, but I will. I began with 10% methanol however I read a comment from GM re acid stripping with reduced methanol. Dropout's suggestion of .95 SG is a good one that I will also try. Your suggestion on draining 50% of the methanol added also has a lot of merit Best regards, jack

quote:

Originally posted by dkenny:
jackmac,
thanks..
your touching on one of the biggest problems in homebrew acid/base processing. I think by restricting the amount of methanol( it floats on oil) it possible to get water to sink..so to speak.

I have been recently talking with GM about this issue and we float(sank) several ideas on how to get this to happen if it doesn't happen on its own.

I think the amount of methanol used in relation to the %FFA will help determine whether the layer sinks or floats.

questions for you:
what titration are you working with?
what percent ( by oil volume) are you using in the acid stage?
how much acid are you using per liter?
is the acid quantity base on titration?

I've heard rumors of some of related information coming on future publications but I don't know details.

fyi. from a limited number of samples I seeing that the amount to drain( I know, I'm one against draining) is about 1/2 the amount of methanol used in the acid stage.

-dkenny

I began a batch on Saturday, titrated at 6.75 NaOH for 51 gal plus 5 gal of undemethed glycerol. Heated to 140F and added 231 ml of H2SO4 to 5 gal methanol and processed 14 hours. Processor off at 10am sunday; settled 2.5hours. Drained off 4 gallons of very light tan thin settling followed by gallons of oil. Titrated at 6.0. Added the oil portion back to the processor and added 1 gal of methanol + 250ml of H2SO4, and set the timer for additional 14 hours. I will report results. Any thoughts? thanks, jack

I don't know if you would call this "consistent", but my last 2 Acid/Base batches have been done this way, and its the best results I have gotten so far;

1) Oil titrated at 9ml KOH (Batch A) and 8.5ml KOH (Batch B).
2) 10%vol new methanol and 1.5ml/L oil (Batch A) and 1.25ml/L oil (Batch B) of acid.
3) Set processor timer to turn on the HF pump for 3 hrs at a time, twice a day for 4 days.
4) Batch A ended at 3.3ml KOH, Batch B ended at 2.2ml KOH.
5) Process as normal using reclaimed methanol (11%vol) in the base stage.
6) 5% water prewash on Batch B.

When I have done similar Acid/Base batches running the pump non-stop for 1-2 days, I haven't gotten as good results (drops to about 6ml KOH: sample size 3 batches). These batches only mixed for 24hrs total.

When I have used reclaimed methanol in the acid stage I don't get as good results (drops to about 5-5.5ml KOH: sample size 2 batches).

When I skipped the 5% water prewash on Batch A, I thought I got horrible yield, as I drained off 1.5 times more glycerin that expected. 2 days later, the extra BD had risen in the glycerin jugs. That 4 gallons of fuel took 56hrs to separate from the glycerin!

jackmac,
I not sure if the glycerine in the first acid stage will help? my thinking is if the glycerine is basic in nature it consume the acid creating a salt..

I'd like to know the results.

thanks


-dkenny

Thanks Ryan. I believe your reclaimed methanol may contain some water and the acid pulled it out and caused a poor reaction on the base stage. I am thinking that the methanol on top of the BD layer may indicate just too much methanol. I have a mini batch in the sep. funnel where I added glycerol after processing in hopes that the gly. will combine with the water and methanol and combine into a denser level than the esters for easy removal. Right now I am not too optimistic as I used 14% methanol on the base stage(can't read my own writing!). I am using sodium methylate for a catalyst and I suspect that product has little tolerance for even a small amount of water. Thanks for the reply, jack

quote:

Originally posted by dkenny:
jackmac,
I not sure if the glycerine in the first acid stage will help? my thinking is if the glycerine is basic in nature it consume the acid creating a salt..

I'd like to know the results.

thanks


-dkenny

dkenny, I believe that your assessment is accurate, and that the glycerol did consume the acid, and converted it to the dense, light tan almost emulsion colored but very thin in viscosity. I have taken a sample of the remaining oil to do mini batches. I added 60 ml glycerol at the end of the acid stage to a 600 ml oil batch, shook it up in a sep funnel. It turned into a dark tan emulsion with no separation over the first 6 hours. This morning there is some settling with 3/4" of cloudy oil on top of the glycerol layer which seems to have bound up a significant part of the oil and methanol. It would appear, based on the rate of separation, that complete separation will take some extended time. The second mini batch of 500ml treated with .8 ml acid in 50 ml methanol ran 14 hours in the mag stirrer at 140F and titrated at 2.75. I will be doing the base stage in a bit and will report. best, jack