Biodiesel Colour Change.

[dgs]

                                                     

Here are some photo's of oil/ biodiesel.

Left to right are No's 1 to 6.

No1 untreated oil from my IBC

No2 the same oil, blended with 20% new soy and glycerol pre-treated.

No3 new soy oil

No's 4, 5 and 6 finished biodiesel from the same batch. No5 has been kept in a darkened shed, whilst 4 and 6 have been left in the sun (well, as much sun as we've had in N yorkshire over the last few days)

From comments some members have made over on vod it seems the most likely cause of No 5 turning the colour of 4 and 6 is free radicals acting on the red (carotenoid) colour in the bio.

I dont remember No1, oil ex IBC being as dark when I pumped it in (although I don't have anything to compare it with)
This IBC is south facing and I'm sure the sunlight has caused it to darken over the weeks.
I wonder if sunlight acting on oil promotes carotenoid formation, hence No 5 being so pink looking. But if the pink colour is due to carotenoids why should it increase in sunlight in oil and decrease when as biodiesel.

[Julian]

Your grass needs cutting!

[dgs]

I know you won't believe this but it is intentionally kept at that length for the geese (2 to 4")

[Julian]

I know you won't believe this but it is intentionally kept at that length for the geese (2 to 4")

Short geese!

Oh, and yes, I've noticed a similar colour change on samples in tubes compared with the same bio in a barrel ... both in a dark shed with no windows though. 

Could this be connected with the brown dropout may of us see from finished bio.  Speaking of which, how are you efforts at centrifuging coming along?

[Julian]

Just demething a batch now.

I'll keep a sample in the dark and put another outside in the grey, misty drizzle!

[Julian]

Dave, if you check out the page where I've been valiantly and single handedly carrying out Nick's suggested test ... http://www.biopowered.co.uk/wiki/Biodiesel_and_oil_oxidisation_collaborative_trial

There's a notable difference in colour between the pure bio in the first photo compared to the second.

[dgs]

Do you mean the 2x photo's on vod. If so it is the difference in the light, there is no difference in the finished bio colour after a day or even a few hours if sunny when stood outside. The 2x cubies of 'bleached' bio in the photo, (No's 4 and 6) may look slightly different as one is filled to capacity, no air, not even in the handle to eliminate the possibility of oxidation.

The centrifuge is working ok but ideally I need a stronger pump. It presently is working at @ 45psi and should really be at 80psi. Although it works it isn't putting enough G on the bio to work as well as it should. At 80psi it creates 2000g at the edge of the bowl. I may have to contact Nathan and see if he still has his 8lpm pump. Out of a 200 litre batch there is enough brown paste to just discolour one square of toilet paper (looks like sub-micron glycerol)

I remember you have mentioned this brown dropout before from your bio. Sorry to be non helpful but I have never noticed anything like that in mine. let me know how the bio colour change goes.
Dave.

Ah, with you now, you mean sample on the right in your photo's. yes, I see the change. Could be a similar thing to my observations.

[Julian]

These two photos ...



and

[dgs]

I intentionally put only about 1mm of bio in my petri dishes. They can now be turned upside down and nothing falls out.

[Twenty4Seven]

My samples look like Julian's but not so pronounced in terms of colour change. I think this is because the metals in my samples are completely submerged by the bio. The viscosity is probably similar to that of unconverted oil now. Still no sign of acidity on the nose - which does surprise me. Maybe the acids are volatile and are lost because they are totally open to the air. Might try another sample in a closed jar.

[dgs]

Here are the next pics, left to right, 1 to 4.

1 glyc washed oil left outside (has gone slightly lighter)

2 same oil as No1 straight from tank (inside)

3 Oil from outside IBC, south facing. (my initial thoughts on this one were incorrect, I thought it had gone darker but has actually gone lighter)

4 Oil from same pub as collected.

It seems as though it all goes lighter when left outside. Oil as collected, glyc washed or finished bio.

Any Change with yours Julian.

[Tony]

It it light or heat? Bio left in the sun gets pretty hot, especially if it's dark in colour. Maybe leave one sample outside but in a couple of bin bags?

[dgs]

Good idea Tony but I'm pretty sure it is the light.
Last week I put two cubies of bio outside, this was during two rain days where there was no direct sunlight. They took two days to lighten whereas in direct sun it takes 4 to 5 hours.

Also in my small shed where the cubies are kept it gets pretty hot when the sun is on it and no colour change with the bio in there.

I remember seeing some bio advertised on ebay a while ago. It was very light coloured. The description said it had beem made with a 'new' type of process. Subjected to U/V light perhaps!

[Julian]

Just demething a batch now.

I'll keep a sample in the dark and put another outside in the grey, misty drizzle!

So, one month on ...  left-hand vial has been wrapped in paper and stored in a shed with no windows, right-hand vial has been hung outside on a South facing porch exposed to what little sunlight we've had from 10:00 am to sunset.

Colour difference is slightly more obvious than is evident in the photo, but still not very marked.

[dgs]

Thanks for trying that Julian.

Hmm, don't really know. I'm thinking my bio is very pink when finished, which is the colour that fades. I wonder if it's anything to do with using a lot of glycerol for the pre-wash and enhancing it with methanol.

I just finished processing a batch yesterday, it's just sat in the processor with glyc draining off before I de-meth. It looks really pink. This batch wasn't done at ambient (for one reason or another) so can't be anything to do with that.