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chemical wash

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November 10, 2014, 01:26 PM
greenface
chemical wash
i just started using magnesium silicate to wash my bio.
i do 1000 liters at a time.and add 1 kg per 100 liters = 10kg
mix it for an hour and let settle for 12 hours.
(what i have noticed so far in 3 batches i have done is. a)i do a water test 50 bio and 50 water, it comes out clear but a very thin layer of soap forms after a while. b) if i let the bio settle for a few days i find white stuff at the bottom. c.after 12 hours of settling the bio looks orange ?
WHAT I NEED TO KNOW...
1. am i using the correct amount of magnesium silicate ?
2. am i mixing long enough?
3. is the settling time sufficient?
4. IF I WATER WASH (1 wash) before doing the magnesium wash will it make any diff ?

any advice help will be appreciated
November 10, 2014, 02:39 PM
Dgs
Hi greenface,
I also use magnesol (sometimes) to help purify my bio.
There is a calculation somewhere indicating the amount to use per litre for any given amount of soap.
I must say 10kg seems a lot even on 1000 litres.
You really need to determine your soap levels by the normal soap titration to find out how much magnesol to use.

If you water wash first, you will have to dry the bio before using magnesol.
Your mixing time is long enough.

Using a synthetic mineral compound to purify the bio can damage your engine if not completley removed.
Ideally a settling time of at least 24 hours is needed and the bio drawn off from well above the settled magnesol.

It then needs to be filtered through at least a 1 micron filter (I use 0.5 micron)
Hope this helps you.
November 11, 2014, 03:46 PM
Dgs
I just checked on the magnesol useage and it's 1% by weight for every 1000ppm soap, so you maybe are not too far out with your 10kg/1000 litres.

I water wash and dry my bio before using magnesol and use @ 500gms in 300 litres and then only if the bio looks darker in colour than I would like, as the magnesol lightens the colour.

Whatever you do, don't use it on wet bio, it will make a mess!
November 13, 2014, 03:08 AM
WesleyB
Demeth the biodiesel prior to treating with magnesium silicate. Magnesium silicate adsorbs the more polar components from the crude biodiesel. Polar methanol molecules would be competeing with polar soap molecules for spots on the surface of the solid magnesium silicate adsorbant. I made biodiesel from about 1 litre of beef tallow. After demething the crude biodiesel product and allowing it to settle, removed the additional fall out material. Tested the remaining biodiesel for potassium soap content. Soap content was about 1154 parts per million. Put the approximately 800 millilitres of biodiesel from beef tallow in a round bottom boiling flask fitted with fast magnetic stirring. Put 10 grams of magnesium silicate into the crude demethed biodiesel with fast magnetic stirring at about 50-73 degrees centigrade for one and three quarters hours. Turned off the magnetic stirring, allowed the magnesium silicate to settle out for about an hour. Poured the biodiesel off the top (decanted) and retested for potassium soap. It was about 64 parts per million soap. Two days later I vacuum filtered the biodiesel through a 1 micron filter paper, then tested for soap content again. It was about 26.7 parts per million potassium soap. There was about 750 millilitres of biodiesel product made from beef tallow. I didn't use a formula to figure out how much magnesium silicate to use, I guessed. Maybe I guessed close to right, at least in this example.
November 23, 2014, 05:18 AM
greenface
thanks guys for the valuable input.
this is what im currently doing but still with a little problem.

i do reaction as usual and 5% pre wash. after settling i remove all glycerol.
pump in2 wash tank and do dry wash with magnesium silicate. settle for 24hours,remove magnesium and filter bio through bag filter and three 1 micron filters. all looks good but the bio still has small particles floating around (if i leave to settle it has a milky substance forming at the bottom of the tank) i want to try a single water wash after filtering, will this help to remove the remaining magnesium in the bio ? thanks in advance
November 23, 2014, 06:50 AM
Dgs
Hi greenface,
Your problem seems that you have wet bio and magnesol in the mix. I can tell you from experiance that this does make a milky mess.
You need to only add magnesol to dry bio. After your 5% prewash your bio will be very wet (over 1000ppm water)

5% prewash your bio, then water wash, then dry. After this you can use magnesol if needed.
November 24, 2014, 02:55 PM
greenface
guys, just 1 thing confusing me...
if i water wash after i drain out the magnesium, will the water remove the remaining magnesium in the bio ? reason im asking is, i know magnesium is not soluble in water or am i missing something
November 24, 2014, 06:13 PM
Dgs
Hi greenface,
If you are able to water wash, I would suggest you do that first.
Then after drying use the magnesol (when I do this it is to lower the colour in the bio)

If you do it the other way around and add magnesol to the crude bio at the rate of 1kg/100 litres I think you will find it too expensive. Also it is difficult to remove all traces from the tank bottom when you water wash.

Have you ever considered using the mineral form of magnesium silicate ie sepiolite. This is like fine gravel, it removes soap and lightens the colour.
You can use it in a column and when spent can be back washed with methanol and can be re-used.