Wiki page for members bio oxidisation tests

[dgs]

I will add comments soon, most noticeable change with mine is the increase in viscosity, one with steel has rusty coloured bio around it. It's got to the piont where the petri dish can virtually be turned upside down without anything dripping out.

[Twenty4Seven]

Likewise - the most noticeable thing is the increase in viscosity.

Perhaps because the metal in two of my samples is completely submerged, the discolouration is less than I was expecting. Also, no hint yet of the acid smell I sometime get when opening an "empty" cubie that has held a few ml of bio for some weeks.

Nick

[Tony]

Also, no hint yet of the acid smell I sometime get when opening an "empty" cubie that has held a few ml of bio for some weeks.

That's interesting, I've experienced exactly the same thing, never really thought about it though (it's always been from a cubie sat in the sun with a splash of bio at the bottom).  I always assumed the smell was from the plastic/previous chemical residue.

[dgs]

And me, I would't call it an acid smell but it's sharp to the nose when you open the cubie top. All the cubies that I use for bio have only had new oil in them. I then wash them out with bio before using them for same.

[Julian]

Just added another update ... getting quite colourful now.

[Julian]

The wiki page seem to have rather died a death, but I've still got my samples sitting outside under cover.

This is how they looked in July last year ...



The colours have deepened dramatically, but the viscosity of each is interesting.

In an overnight ambient of -1°C the plain bio sample is a lot more viscous but will still pour, the iron sample is solid and very firm, but the copper sample is only a little more viscous than at the start.

Bio in my storage tank below the samples looks quite normal.

The chemistry is beyond me but the marked difference between the three is quite puzzling.

[dgs]

Sorry, Julian.
I had almost forgot I still had the samples on my bench. The one with the piece of steel immersed in it looks like rust leaching from the metal. Both samples have polymerised in that both dishes can be turned upside down without anything dripping out. My samples have been kept inside the bio room and therefore generally warmer than outside.

If we were expecting oxidation to take place in that the bio would become dark coloured then personally I would say that the oxidation has not taken place.

[Julian]

I wasn't pointing a finger, Dave!

The page seemed like a good idea when it was suggested, but few participated ... shame as this sort of thing could collect a good spread of information.

I still want to know why my iron sample has gone solid and the copper sample is still runny when both are the same bio.

[Jamesrl]

I still want to know why my iron sample has gone solid and the copper sample is still runny when both are the same bio.

Could it be them Rusticle bacteria affecting the bio?

[Julian]

I still want to know why my iron sample has gone solid and the copper sample is still runny when both are the same bio.

Could it be them Rusticle bacteria affecting the bio?

It's comforting to know there's always an expert on hand to offer advise.

[Jamesrl]

It's comforting to know there's always an expert on hand to offer advise.

Surely you've seen what the iron eating bacteria have done to the Titanic, and gawd knows what they poo out.

[Julian]

I've seen what bacteria can do to injectors springs on a large generator on an RAF "early warning system".

[dgs]

I still want to know why my iron sample has gone solid and the copper sample is still runny when both are the same bio.

Could it be that whatever is causing some sort of reaction between the copper and the bio is stopping polymerisation.

[countrypaul]

Given that the samples are open to the atmosphere and therefore humidty it could be that the samples with steel present are showing the effect of more rapid corrosion. Once steel (primarily iron) starts to rust the crystal structure is such that it opens up more area for further corrsion, whereas in copper I believe the crystal structure of the copper oxide is more akin to that of black iron oxide in that it is larger than the underlying metal and effectively seals the metal in a protective envelope.

Iron complexes may be easier to form than copper ones due to the larger surface area of the rust particles. The unsaturated double bonds in the bio could then complex more easily with the iron, or form polymers more easily. Either way this formation of larger molecule would result in higher melting points or the whole sample going solid more easily.

One factor I could not see taken into account was light. If the samples were in direct sunlight then free radical formation would be much more likely leading to rapid polymerisation. I would expect samples in the dark to polymerise more slowly.

Has anyone looked at how to measure whether there has been increased oxidation, or just polymerisation taking place?

[Julian]

Thanks for that, Paul ... I'm afraid most of it went over my head, but a little computed!

The iron sample is cast iron.  The samples are not in direct sunlight, but have every opportunity to absorb moisture from the atmosphere.

The thing I found strange was that the bio sample was more viscous than the copper sample ... as if something from the copper contamination was inhibiting gelling.

At current temperatures (circa 10 - 11°C) all samples are liquid to various degrees.