Still soap left in bio?

[Islebio]

Hi,

I use a JL processor with a condenser and dont waterwash. I am measuring the WVO to start with at 200 litres ( i manually poured 10 litre container in to measure) I am using a two stage process with a 20% Methanol and a 6g per litre Potassium methoxide mix. I react until a good 45/5 test is achieved then start demething. I achieve a good demeth up to 11 litres then cant seem to take any more off regardless of whether its 70'c -90c. I then transfer to a bubbler and let bubble overnight until cold in the morning. After settling for a few days i take a sample off the top and am doing a 50/50 soap test. I am getting quite a lot of soap still left in the bio, any ideas?

Cheers

Rod

[Julian]

Hi Rod,


What sort of quality is your feed stock?

[dgs]

Hi Rod. Using potassium the soaps take ages to settle. If after your bubbling you really want to wait until your soap level is within spec ie less than 66ppm then you will have to wait literally weeks.

A friend that bubbles and settles is very keen on doing soap titration tests and his soap level after settling 1 to 2 weeks is 2 to 400ppm.

He then filters through hardwood chips which will easily bring his soap level down to zero. This is an easy and cheap method if you don't want to water wash or wait the long settling time.

Dave.

[Islebio]

Hi, The feed stock is good, from a chip shop, changed every couple of weeks, so pretty clean. I have only recently started having this problem, i have been making bio for about a year and a half now, could it be a temperature thing over the winter? I have been using potassium since the outset and usually it clears within a few days to a week. I have a media tower with ecopure media ( basically hardwood shavings), but don't want to rely on that for bringing all the soap out. Should i consider heating it back up and rebubbling for a longer period to try to get the meth out of it?

[dgs]

I cannot see that the residual soap is due to any methanol being left when you have heated to the temperatures you state.

When you say "it usually clears between a few days and a week" do you mean that after bubbling your bio is still cloudy?

Although the shake test is a good guideline and easy and cheap it does not give a quantitative result. A soap titration kit is very accurate and easy to use and would probably point you to where the problem is.

You will find if you use your ecopure tower the soap will be vastly reduced or zero, that's what the media is designed for. True, it will lower the life if you pass bio through with a high soap level, but without knowing what the actual soap level is (only that your shake-up is cloudy) who can say.

The cloudy shake up can also be due to residual glycerol.

There is another method you can use by adding pure glycerine to the settled bio and mixing (2 to 3 litres per batch will do) when it settles out it will remove most of the soap. It is expensive like @ £40 for 20 litres but you can use it many times over.

[Tony]

I do what you do and yes, in the winter it takes longer.  If you can container it up and put some in a warmer environment, that will speed it up (greenhouse, or carry 25l with you in the car).

[Islebio]

HI DGS, What i mean about clearness, is the soap content after the test,l the bio looks very clear when i take a sample of it. I have attached a pic to show what the results look like just now. Am interested to hear about adding Glycerine, it is just mixed by hand?

Tony, should i be looking at heating up the bio in the settling tank, will that increase the drop out rate?

Cheers

Rod

[dgs]

I see what you mean re your sample, The emulsified layer between the water and bio looks to me as if it could contain a high % of monoglycerides.

Re the pure glycerine wash. When your bio is de-methed and settled and the soap content gets to lower than around 400ppm if you wash the bio with a few litres of the glycerine, something like 5 litres, it will absorb most of the soap left in the bio. If it is left a few days to settle you should find the soap level is less than the 66ppm we are allowed.

It needs to be pump mixed for 30 mins at 30degs. I use a compressor to mix in my wash tank. If you use your pump you have to make sure your pump system is purged of all ex-process glycerol. The 5 litres of glycerine used can be used many times until it is less effective because of the soap it has absorbed.

Glycerine can absorb huge levels of soap and water, the reason our glycerol ex process doesn't absorb the excess is that it is saturated with soap. Depending which catalyst you use up to the 40% level.

I water wash but after de-mething and settling if the soap level isn't low enough to aggressively water wash I simply give it a wash with the glycerine first.

When I first was testing this method I once reduced the soap in a batch to < 20ppm using multiple washes with the glycerine and this was without de-mething.

The method works better if the soap level is lowish to start with, then the pure glycerine doesn't have as much work to do and can be used more times.

It is very strange running off the glycerine after washing, it is much lighter coloured than the bio.

[Glycer-rides]

Great info. on the pure glyc. method of finishing, Dave.

I see a group buy looming on this, if that'd make it more cost effective?

I've just switched to K after 7+ years, so feeling a touch nervous on my de-meth / settle staple!

[julianf]

Its only the sodium soaps that are solid at room temp - once they are stripped out, then the glycerol should be liquid - same as it would be when the potassium soaps are stripped.

[dgs]

Great info. on the pure glyc. method of finishing, Dave.

I see a group buy looming on this, if that'd make it more cost effective?

I've just switched to K after 7+ years, so feeling a touch nervous on my de-meth / settle staple!

Thanks Glycer-rides,

I did notice a while ago that Trinity advertised glycerine. Every time I phone them I forget to ask them, it was only on their site a short time.

Of course the glycerol from the cracking/acidification process works as well after neutralising. It can be a pain to do in cubies, trying to syphon the layers is difficult, it really needs a dedicated tank.

julianf, Good call. I'm sure you are correct. During a couple of processes i did a few months ago towards the end of de-mething the glycerol and soap split, leaving semi solid soap in the wash tank, easily removed with a hot static wash. I have never been able to work out what actually caused this and it has never happened since.

The pure glycerine wash is not my idea, a commercial friend of mine did it a few years ago. He said it also lightened the colour. It was too expensive for him and he went on to distillation of the bio.

[Islebio]

Thanks for all the posts for the info, have learned a lot of useful stuff. I am going to purchase a soap titration test to get an accurate result on what is going on. I have also put the bio back in the processor and going to heat to see if any more meth comes off then bubble again overnight. I have also bought an element for the bubbling tank so will put a bit of heat in it to see if it settles any better.

Cheers again