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Biodiesel entry
By wildbill hickup, Section Diaries Posted on Mon May 30th, 2005 at 12:03:50 PM MST
Update on clouding problem

To all,
JUst some updated observations. It seems as though I may have had a bad batch of lye. Can't be sure that was it but I turned out 2 more 20L batches and both reacted OK but stayed cloudy, added a little more lye and meth to each and the problem cleared. THe total amount of lye was quite a bit over what the titration test called for in each case. In one other case where I had already washed the batch I just finished it as normal and then retested (titrated) it. The titration called for 2g per L. I am processing that one now as a new batch and will see what happens. Troy does that sound like a possibility? Another idea is that it's the humidity in the air. It has been very humid lately, like to weeks of rain,cloudy,foggy, rain,cloudy foggy... well you get the idea. I have tried to expose methanol and lye to as little moisture as possible but I do have to mix outside (undercover) do to the fact I haven't built any breathing apparatice for the shop yet. I've got a new can of lye and have mixed a new batch with it, I guess now we wait to see what happens.
WEll that's it for now, for what it's worth
Wildbill

Biodiesel entry | 5 comments (5 topical, 0 editorial)

Biodiesel entry (3.00 / 0) (#1)
by richhagen (richhagen (a t) Juno.com) on Mon May 30th, 2005 at 02:40:20 PM MST
(User Info)

If the lye is exposed to the air, it will absorb water and then carbon dioxide out of the air. As this happens over time, the carbonic acid formed when the carbon dioxide disolves in the solution it will quickly react with the sodium hydroxide and the lye will lose effectiveness as the sodium carbonate formed is probably useless for your reaction. Keep the lye sealed from the environment as well as possible. I am not sure on the methanol, but if it is completely dessicated, it may absorb water from the air as well. Rich
'A Joule saved is a Joule made'

Re: Biodiesel entry (3.00 / 0) (#2)
by wildbill hickup (wildbill_hickup at yahoo.com) on Tue May 31st, 2005 at 04:45:50 AM MST
(User Info)

Thank's

That pretty much covers what I thought, but you just explained how. The methanol will also absorb water from the air(so I have been told). I'll know if it was the lye tonight when I work on this new batch, new can of lye exposed to air about 3 minutes (while measuring and mixing with meth). If this one is cloudy then it's got to be the humidity. Sure wish I could mix indoors where it's dry. May just windup waiting for the weather to improve a bit and then see what happens. Maybe take the time to build the breather I want for my shop, who know's if Murphy's Law is true to form, once I get it all built the weather will clear and I'll be able to mix outside again.

Thank's again for the explaination on the lye.

Wildbill

[ Parent ]

Re: Biodiesel entry (3.00 / 0) (#3)
by troy on Wed Jun 1st, 2005 at 01:59:34 PM MST
(User Info)

I concur with Rich. Sodium hydroxide will suck the moisture right out of the air, and fast. And if your titrating solution was made with fresh lye, but you're reacting with "old" lye, you would get pretty much the results you describe.

Another test you could do is to make up a new batch of titrating solution with your old lye and see if it titrates the wvo to the same numbers as your previous titrating solution. If they differ significantly, that's your culprit, or at least a big part of it.

I mix indoors in the basement, but I replaced one of the basement windows with a custom ventilation fan that does a nice job of it.

Humidity matters.

Finest regards,

troy

[ Parent ]

Re: Biodiesel entry (3.00 / 0) (#4)
by wildbill hickup (wildbill_hickup at yahoo.com) on Thu Jun 2nd, 2005 at 02:49:05 AM MST
(User Info)

Thanks for your idea on a different titration solution. I'm still using the batch I mixed up from a previous can. Picked up a new can the other day. I haven't got a chance to us it yet but starting with that one , and all in the future I think I'll make a fresh titation batch with each change of lye. I had 2 successes on the old can by adding 10% to the quanity called for and both seemed to work OK. Don't have much left of that old can so I think I'm just going to move on(although now you've got me curious). The weather has also improved here so mixing outside shouldn't be as much trouble. Soon I'll have my breather set up in the shop and weather won't be a concideration.

I do have another question for you though. Somewhere I read that the glycerine layer should be simi-solid at temps lower than 100F. On most all the batches I've made I have wound up with what appears to be a glyerine layer (dark chesnut color) non of which are solid or simi solid even down to temps of 45 of 50 F. Am I getting a true glycerine layer?

[ Parent ]

Re: Biodiesel entry (3.00 / 0) (#5)
by troy on Fri Jun 3rd, 2005 at 11:25:03 AM MST
(User Info)

Dear Bill,

Glycerine is highly variable. It may stay liquid or it may not. The key issue is if you have clear separation into two layers after reaction and settling by proper cookbook methods. The lower layer will be darker and more viscous. If that is true, it's glycerin. You should also get a certain volume, between 10 and 20% of the original volume as glycerin. If you get less than that, or more than that, something is probably wrong.

A higher percentage of methanol will tend to keep the glycerin liquid, the use of KOH instead of NaOH will also keep the byproduct liquid better. The presence of water (which can cause all sorts of other trouble...) will keep the glycerine more liquid. The age, quality and type of oil will also affect the glycerin somewhat.

HTH,

troy

[ Parent ]

Biodiesel entry | 5 comments (5 topical, 0 editorial)

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