I am new to making biodiesel so forgive my ignorance but I need some help. I am working with a 35 gallon batch that titrates at 14.5 w/KOH. I did an acid wash with 266 ml of sulfuric acid(93%) and 4 gallons of methanol. I heated the WVO to 60 celcius before putting it in my processor. My processor does not have a heater built into the tank. I let it run for 3 hrs at a time before pumping it back into the heating barrels to reheat the oil. This process has been going on now for 15 hrs and still no change in the titration level. If I need to do another wash do I just add more Acid or do I need to add more methanol as well. Any help would be greatly appreciated.

Was the oil dry?

Your acid and methanol numbers are close to what I would use. The catch 22 in the acid stage can be stated as follows:

This process creates water
Water stops this process.

Thus if you had much water in place to start with, you're inhibited from the very beginning.

Horn

I think the oil was dry. I dewatered the batch the night before by heating it up to 60 celcius then let it cool over night. When I took it out of the barrel I left the bottom 8 inches or so assuming that is the water.

I'm not sure if my acid wash problem is the same as chargerpr or not. My oil is titrating at 14.5 w/ KOH. Can I still go ahead with the base method with the titration that high? If so is there anything I need to do in order to get a good result? I just don't want to keep making mistakes if for no other reason than Methanol prices were I am are rediculiously high and I can't really afford to make to many bad batches. If anyone has any thoughts I would love to here them. Thank you.

I agree with Horn. The oil is probably wet. I like to heat to 110 C and watch for signs of water. Also you need to keep the temperature to at least 60 C for the reaction to go at any resonable rate. I feel that if the oil is wet and titrating at 14.5 you would have a mess if you use the base only. I like to see titrations of no more than 4 or 5 for resonable results on the base method.

there are some other things that might have cause the problem.

some acid besides FFA causing the high titration reading. it was in the oil when you started

water

I figure you needed to use 291ml of acid not 266.


you might try something, sample size only!!!
take 500 ml of what you have.
mix 200g of baking soda in 500ml of water.
mix water and baking soda until dissolved.
mix oil, water/baking soda together

wait then recheck the titration

I have had what your describing happen to a couple of time, but haven't finish working out a solution

I would not proceed with the base stage at this point. your yield will be LOW!!50% or less..

-dkenny

Thanks for the info everyone. I will reheat the oil up to a higher temp and see if I get any water that way. I will also try the baking soda idea dkenny. One question though, what is the baking soda going to do exactly? Is it going to nuetralize what ever else is making the titration level so high? OK- more then one question. Should I heat the oil up for this baking soda test? How long do I wait before re titrating?

if you already have methanol in the don't heat it hotter to see if its got water. the methanol will boil out first!!!

yes the baking soda should neutralize the acids. it might also turn some of the FFA into soap.

don't know about the heating with baking soda

-dkenny

Success at last. You guys were right on the money. I pulled some oil out and did some test batches. After heating up the oil enough to boil out the water I re did an acid wash and low and behold the titration landed at 3 within 4 hours. Thank you Horn, Cat123 and dkenny for all your help.
I didn't get a chance to do a sample batch trying the baking soda you suggested yet dkenny but that is on my list of things to do.
Thanks again for all the help and Im sure I will be asking more questiions in the future. It's good to know there is a place like this to go for help when you need it.

you're welcome..

I know I needed help when I started. payback has been lots of fun. maybe you too can help other in the future.


-dkenny