Washing out monoglycerides.

[dgs]

Just scanning some old posts and came across this one from Manfred from his thread 'pump wash gone wrong'
 
Pump wash gone wrong.
« on: March 01, 2014, 10:50:11 am »
Quote
After a perfect 10/90 on a 90 ltr mix I did a pre wash then 3x 10 ltr pump washes. Result  the water was sparkling clear. So being the sort who  prods wet paint to see if it's dry I did one more wash. Bum soapy water with a white interface. No worries I put 2 ltr of Glycol and mixed, looked ok so added 10 ltr of warm water. Instant mayonnaise so I added acid until split. Peed me off as I didn't want to do this because of interfering with the acid soap test. So now I'm back to square one. Has anyone else experienced this ?

I am almost sure what you have experienced is an emulsification due to a high amount of monoglycerides being present. They don't show up in a 10/90.

I have had this happen many times. After several aggressive washes with my compressor (wash water clear) I decide to do one more, then forget about the time and leave the thing (lets say) 45 mins. Leave it to settle, approx 30 mins. When running off the water there is the emulsified layer between the water and bio. Very thick, like white sauce.

I have to be carefull with this nowadays as I react at ambient. I only heat after a clear 10/90 and leave the last reaction glycerol in the mix. I heat to 55degs and mix for 30 mins just prior to de-mething. This seems to convert the mono's so
I don't have the problem anymore.

For some reason I've found if they are going to show it will be at the back end of the wash cycle.

[Jonzeyboy43]

I did post about this prob over on VOD. Apart form the leccy what is the advantage of ambient conversion how much longer does it take

[dgs]

I did post about this prob over on VOD. Apart form the leccy what is the advantage of ambient conversion how much longer does it take

Probably up to 30% longer, thats all. It's really convenient not to have to keep re-heating between reactions. I've been trying to glyc wash at ambient recently, although the glyc separates ok I don't think it works as well. I usually glyc wash using the M67 set-up / tam120/ 1000litre conical and do 2 batches at once.

[Jonzeyboy43]

I usually react straight from glyc wash so I'm usually still at 50 ish

[Manfred]

Back end of the wash cycle. More like bite you in your backside when you think it's all done.
Having a similar problem with some palmy crap I'm using up. Real good pass, reclaim some meth then wash. Cold water then all of a sudden Bang. White tendrils hanging in the water. I carry on some more then dry. When settled for a week I get fallout in my drum so decant into smaller cubbies to force some more out. At least I know it's the oil so I'm watching for it.

[dgs]

Hi Manfred, Yes, they come along, those naughty mono's, Captain Mannering Sir and bite you in the bum!

On the serious side if you want to be bothered you can get rid of them by doing a further reaction even with a clear pass. Use about 0.5 gms/litre KOH and react for @ 30 mins.

[Manfred]

So do a third small conversion after a pass should get rid of them.
 Ok I will be doing a batch on Monday so will give it a go. Will see if I can get a good wash again.

[dgs]

Try it and let us know.

[Manfred]

Try it and let us know.

 Didn't try it this time. Dried the oil, pre wash with added mets. 360g NaOH usually gives me a 80/90% pass then 80/120g to full conversion. This time though only got a 10% first pass. It took 3 stages with Dubble the amount of NaOH to convert it. Instant 10/90. Didn't want to add more because of the quantity already used. Bubble washed to about 120 ppm soap so did a pump wash to finish, big mistake. There back.

[dgs]

Try it and let us know.

 Didn't try it this time. Dried the oil, pre wash with added mets. 360g NaOH usually gives me a 80/90% pass then 80/120g to full conversion. This time though only got a 10% first pass. It took 3 stages with Dubble the amount of NaOH to convert it. Instant 10/90. Didn't want to add more because of the quantity already used. Bubble washed to about 120 ppm soap so did a pump wash to finish, big mistake. There back.

Hmm, you know I've had this minimum KOH thing in my head for the last year or so. After a post I put on VOD Maurice_Mynah came up with the way he processes. Basically he glyc washes then uses 7gms/litre KOH and leaves it for a minimum of 4 hours at 60degs. I never quite managed the 7.0gms with my old processor, think I once did 7.2

Point is after processing all that time (4 to 7 hours) I never once got a hint of mono's when water washing. It seems to me that there are 3 ways to avoid them;

1 Process for a longer time at temperature.

2 After a clear 10/90 do a small re-process at temp with a very small amount of catalyst.

3 if you process at ambient (like I do ) leave the last reaction glycerol present, heat to de-meth and use this heat to re-mix at temperature before de-mething.

Trouble is with mono's they are invisible as far as a 10/90 is concerned. Also for those who bubble/settle there could be lots in their bio and they will never know.

As far as specs are concerned they will come under the category of free and bound glycerine which from memory is 2400ppm so they are best removed. Good job we both water wash Manfred.

[Bio-boy]

dgs - you process at ambient temperature???

[dgs]

dgs - you process at ambient temperature???

I certainly do.

http://www.biopowered.co.uk/forum/index.php/topic,2442.msg30857.html#msg30857

[Bill]

The conversion of mono-glycerides to bio is the final step of the conversion process. Triglyc.=>Diglyc=>monoglyc=>methyl ester. Each stage is a reversible reaction. So there will always be some mono's present.
They can be reduced by driving the reaction to the right i.e.

Feedstock (oil) + reactant (methanol)+catalyst <=> product (bio) + By-product (glycerol+ water)+ catalyst (which also forms soaps)

The reaction is driven to the right by removing something from the right hand side or adding something to the left hand side. By adding more methoxide you are adding to the left hand side. This is a bit of a simplification of a complex reaction. I'm sure a chemist can explain better.

[Twenty4Seven]

The conversion of mono-glycerides to bio is the final step of the conversion process. Triglyc.=>Diglyc=>monoglyc=>methyl ester. Each stage is a reversible reaction. So there will always be some mono's present.
They can be reduced by driving the reaction to the right i.e.

Feedstock (oil) + reactant (methanol)+catalyst <=> product (bio) + By-product (glycerol+ water)+ catalyst (which also forms soaps)

The reaction is driven to the right by removing something from the right hand side or adding something to the left hand side. By adding more methoxide you are adding to the left hand side. This is a bit of a simplification of a complex reaction. I'm sure a chemist can explain better.

Just Google Le Chatelier's principle - that will tell you all about equilibrium reactions.

Here's a start... https://en.wikipedia.org/wiki/Le_Chatelier's_principle

[Julian]

The conversion of mono-glycerides to bio is the final step of the conversion process. Triglyc.=>Diglyc=>monoglyc=>methyl ester. Each stage is a reversible reaction. So there will always be some mono's present.
They can be reduced by driving the reaction to the right i.e.

Feedstock (oil) + reactant (methanol)+catalyst <=> product (bio) + By-product (glycerol+ water)+ catalyst (which also forms soaps)

The reaction is driven to the right by removing something from the right hand side or adding something to the left hand side. By adding more methoxide you are adding to the left hand side. This is a bit of a simplification of a complex reaction. I'm sure a chemist can explain better.

I'm so not a chemist , it's all a complete mystery to me, but the explanation of "pushing" the reaction in one direction or the other by adding or subtracting from either side, is brilliant ... suddenly why a normal two stage reaction works makes sense!