See below. >Mark, > >Attached is the FFA recovery "results" photo mentioned yesterday. > >Don't know if Biodiesel accepts attachments. If not, I'll find >someone who can publish it to the web, along the the following >text: > >Both jars are examples of Free Fatty Acid recovery from the >manufacture of biodiesel using potassium hydroxide as the base >catalyst. > >The jar on the left was originally the glycerin layer which had >separated out of straight base reactions. > >The jar on the right also originated as the glycerin layer that >settles out of a biodiesel transesterification stage. The only >difference is that it was from a resevoir accumulated from 2 >acid/base reactions and 2 straight base reactions. > >Both were subjected with the 85% phosphoric acid needed to crack >the soaps and convert them back to Free Fatty Acids. > >The precipitate on the bottom of both jars is potassium phosphate >(actually three different types of potassium phosphate) - >fertilizer. > >The center layer is a blend of crude glycerin, H20 and excess >phosphoric acid. > >The top layer is the recovered Free Fatty Acids. > >While someone will surely note the difference in size between the >two jars (left = 16 fluid ounces and right = 32 fluid ounces), >the important point for this reference is the ratios of recovered >co-products. > >Note that the left jar (straight base) has a higher % of >recovered FFAs and catalyst (potassium phosphate) relative to the >total volume. While the right jar (50% acid/base reactions and >50% straight base reactions) has a lower % of recovered FFAs and >catalyst relative to total volume > >This is the benefit of the acid side of the acid/base process, in >that the FFAs get converted into esters originally, rather than >saponified, which in turn have to be cracked in order to recover >the FFAs. The acid stage also reduces the amount of base catalyst >required, eventually giving cause to lesser amounts of >neutralizing phosphoric acid, yielding lesser amounts of >potassium phosphate fertilizer - MORE BIODIESEL. LOWER VOLUMES OF >CO-PRODUCTS. > >Were there to be a third jar on the right using the glycerin >layer from strictly acid/base reactions, the ratios of FFAs and >potassium phosphate would be even smaller relative to total >volume. > >METHODS OF DISPOSAL OF CO-PRODUCTS: > >The FFAs could be subjected to a high pressure (~100 psi) >esterification reaction and converted to esters. Or, they could >be used as a feedstock for process, commercial and residential >heat. Enter once again devices such as the Babington Burner. >There is no, or almost no glycerin to be concerned with in the >combustion of recovered FFAs - meaning no or almost no >possibility of the formation of acrolein in any combustion >process, whether efficient or inefficient. > >It is also possible that the FFAs could be run in a SVO or WVO >converted diesel engine. I am not aware of anyone who does these >conversions who has accumulated enough FFAs to make such an >attempt. In any event, due to the absence of glycerin, it is >quite possible that such a fuel could work better than SVO or WVO >in both the short and long term. > >The recovered glycerin layer needs to be neutralized before >disposal. This is due to the slight amount of excess phosphoric >acid needed to get the reaction to move in the direction >required. The neutralization can be done with a dilute solution >of potassium hydroxide (which would yield a tad more of potassium >phosphate fertilizer) or with something as common as baking soda. > >Our suggestion is that the neutralized glycerin be diluted >heavily with water and applied to a test area in sprinkler type >irrigation manner, rather than going gang busters and just >dumping it in a compost pile. The "sweetness" of glycerol is >bound to attract some forms of wildlife, perhaps raccoons and >opossums or perhaps specific types of insects. Then again, >perhaps not. > >The potassium phosphate fertilizer will be wet with glycerin and >some micro-scopic portion of FFAs that were not able to float >free before they were covered. For application as a fertilzer, it >should also be heavily dilluted, checked for pH and neutralized >if needed, then applied in the same or similar manner as the >glycerin is recommeded above. > >Just two caveats: > >1) When the potassium phosphate is dissolved, the micro-scopic >FFAs will float to the top of the tank. These should always be >sequestered prior to applying the solution as a fertilizer, as >oils are herbicides - FFAs are oils. > >Consult your local ag agent as to recommended application rates >of potassium phosphate per acre. > >2) Those who use sodium hydroxide as the base catalyst can still >recover FFAs and glycerin in the same manner. Unfortunately, the >precipitate co-product will be sodium phosphate, which has >relatively little or no use in a vegetative environment. > >Our recommendation? Use potassium hydroxide as exclusively as >possible as the base catalyst to eliminate the production of a >non-usable co-product. Generally, 100# open head drums of 92% KOH >flake can be acquired for approximately $0.75 - $0.90 a pound >(US) through bulk chemical supply houses. They should also be >able to make 500# drums and 2,000# bags available for the higher >volume oriented. > >Todd Swearingen
Hi Todd Thanks for this, very interesting. Especially the difference between single-stage base and two-stage acid-base, very telling, good to know. I've been working on how much phosphoric acid to use, with help from a feller named Todd, LOL! So you have to neutralize all the catalyst -- ie, the basic 3.5 gm/litre for transesterification plus whatever titration indicated was needed to neutralize the FFAs. Traces of catalyst will remain in the biodiesel rather than collecting in the glycerine at the bottom, but it makes sense to allow for the full amount of lye used. We use 97% strength H3PO4. I dissolved 1gm of lye in some distilled water, and titrated the solution back to neutral with the phosphoric acid, using a pH meter. Same as usual - drop by drop, while stirring, add phosphoric acid to the mixture until it reads pH7. In this case it took exactly 1 ml of phosphoric acid. To be sure, I tried it again with 4 gm of lye. Again, it took us just 4 ml of phosphoric to bring the mixture to pH7. In our last batch we'd used oil that titrated at 5.6 ml, ie a total 5.6 + 3.5 = 9.1 gm lye per litre. Multiply by the number of litres of oil processed (only three litres in this case) for the total lye quantity to be neutralized -- 27.3 gm. Multiply that by the ratio of lye to phosphoric for the stoichiometric amount of phosphoric acid required -- in this case 1 gm : 1 ml, so it's the same, 27.3 ml. With the stoichiometric amount, a translucent glycerine layer quickly formed under a dark FFA layer, and not long afterwards the catalyst collected at the bottom -- sodium phosphates in this case. The catalyst layer is yellowish, the glycerine layer the colour of light sherry, the FFA layer much darker, with a clear line of separation between each, as in your picture. When it was fully settled I separated the FFA layer and added 1 ml more phosphoric acid to it, and a bit more glycerine formed at the bottom. I kept adding more phosphoric acid, seeking the point at which no more glycerine separated. Currently I'm at a ratio of 2.8 ml phosphoric acid to 1 gm of lye, which still yielded a bit more glyc. That's quite a lot of H3PO4. So, question: have you done something like this? Did you reach a final point? The FFAs (methanol removed) make quite an effective weedkiller, takes a couple of days. I don't know if it's systemic or contact, contact I think, and I also don't know how long residues will take to biodegrade in the soil. Not very long I should thing, a week or two maybe, if the soil's alive at all. It doesn't burn very well, not even in a lamp that will burn SVO. Dunno about a Petromax, maybe okay, nor about such as Whisperlites, also maybe. Should be fine in a Mother Earth Waste Oil Heater though. I believe there should be a market for FFAs. Quite a lot of organics supplies companies produce weedkillers and insect killers and so on made from FFAs. Probably they use soapstock, I don't know, but it should be worth investigating for anyone producing any bulk of the stuff. Best Keith ------------------------ Yahoo! Groups Sponsor ---------------------~--> Save on REALTOR Fees http://us.click.yahoo.com/Xw80LD/h1ZEAA/Ey.GAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send "unsubscribe" messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
