Mixing water and oil: no surfactants needed | Hacker News Reader

Mixing water and oil: no surfactants needed

physicsworld.com

42 pointssohkamyung31 comments

Another way to dissolve oil in water is to increase the pressure and temperature. Supercritical water is a non-polar solvent!

Do we know how and why that works?

How and why are difficult words. I mean, in some senses we don't even know why water is wet. My very limited understanding of the subject is that in supercritical water there are larger clumps of H2O molecules surrounding the isolated H+ and OH- ions and this affects the solvent behavior.

Note that the chemistry of supercritical water is something which is very hard to study -- needing to keep a sample under extreme conditions means that you can't probe it in many of the normal ways. My father did groundbreaking work in this area using Muon Spin Spectroscopy, because he could shoot a beam of muons into a sample which was otherwise inaccessible.

(Shameless plug: My father recently retired and wrote a book on the topic with two of his colleagues. If you search for "Muon Spin Spectroscopy Percival" you should find it in all the usual places.)

> I mean, in some senses we don't even know why water is wet.

That's something that made me go "wait, what?" But then after waiting, and thinking about it, it is just a question that I've never even considered. It's one of those things where I really wished I had better understanding of chemistry.

Wish some of this pathological humility could find its way into climate science.

You don't think there's millions of man-hours of work behind the models, including quite a bit of atmospheric chemistry?

There has been half a century of work put into string theory and there is no shred of humility there, pathological or otherwise.

Amount of work put in is irrelevant.

Fairly well understood partial differential equations which are physically validated or isotopic atmospheric chemistry are a little bit different than string theory

You're not sounding very humble right now

Because you think you do, I guess?

I'm not the one screaming for 100 trillion dollars lol.

A 2009 survey of US temperature stations found that 89% were improperly sited according to NOAA’s own Air Temperature Siting Standards (100 feet from any extensive concrete or paved surface, etc).

A 2022 survey found that 96% were sited improperly.

Do you think that nighttime temperature rising independent of Milanković cycles can be put down to faulty stations?

Of course; if the devices doing the measuring are covered in hot manure once daily or are faulty for an infinite number of other reasons, the data can easily be low quality and/or biased. This is basic science.

The idea that bias only happens in the day is nonsense. Also, I have yet to hear that scientists are writing off the low-quality daytime data either.

As for their fudge factors to supposedly correct the data, I seriously doubt that NOAA are doing regular and representative computational fluid dynamics and raycasting simulations for each of the substandard stations to account for the various obstructions and radiative/reflective surfaces they chose to ignore when placing their sensor. They just have a crappy heuristic based on boolean algebra and round numbers.

They pass off their "corrected" low-quality data as being corroborated by other measurements but what they're really doing is using this low-quality data to corroborate other sources of data. Other sources which only started collecting data a handful of years ago (and thus could not alone support any claim about the industrial revolution causing such and such amount of warming). It's a self-licking ice cream cone.

Also, going back to the humility thing, they never seem to acknowledge that other sciences like chemistry are easily 500 years ahead of climate science. Imagine if I said that the advanced state of computer science was on par with physics (LOL). Remember the xkcd comic? Computer scientists will readily volunteer that their field is an eel pit

You don’t think chemists contributed to climate science? Like Susan Solomon? Or via stuff like [1]

[1] https://en.m.wikipedia.org/wiki/Mass-independent_fractionati...

>we don't even know why water is wet.

As a chemist it makes me want to take a dip in the ocean.

To try and figure it out ;)

Water is wet when you take that dip because it has a small contact angle with skin; is that still chemistry or are we now in physics?

I think they mean quantum mechanically, or London dispersion forces or dipoles

This seemed interesting to me but I didn't fully understand it. The article states:

> Within these normally immiscible mixtures, they observed ultrathin but abnormally stable films of oil spontaneously appearing between the dispersed droplets of water.

And there is more information about what they observed. But I was completely unclear of the procedure they used to get these "normally immiscible mixtures" to behave in this way in the first place. Any ideas?

Here’s the link to the study in Science:

https://www.science.org/doi/10.1126/science.adj6728

I found their editor’s summary informative:

> Basic chemistry tells us that dissimilar compounds such as oil and water won’t mix without the aid of a surfactant. Typically, the addition of a third component is needed to allow droplets of one to be stabilized within the other. Nannette et al. have revealed an exception to this behavior: the mixing of water with a polymeric oil. When a thin layer of oil absorbs onto the surface of water droplets, it stabilizes the droplets and causes a weak attraction between them, leading to long-term stability. —Marc S. Lavine

Their supplementary materials, which include their methods, are openly available:

https://www.science.org/action/downloadSupplement?doi=10.112...

I wish I could access the study itself, but alas. From the methods and discussions it sounds to my layman’s ears like they use oils modified for cross-linking potential then went water-into-oil pretty slowly, in an environment that shears the whole situation into thin sheets at the interface. And that the novelty is that the cross-linked oils, polymerized around these little water spheres, were stable enough to resist coalescing even without the help of a surfactant to repel the little droplets from one another?

Heat can polymerize some oils pretty quickly. Thinking flax oil is a very easily to polymerize one (it's fast but kind of fragile to season cast iron with it). Ever have a bottle of cooking oil go bad and it forms that sticky residue on outside? As I understand this is the oil polymerizing.

Wondering if having oils polymerize makes it so the outside of the linked molecule links in some way that water is prevented from being repelled as well (or it busts it into much smaller droplets they couldn't see). The abnormally stable part throws me off though.

If someone could liberate this paper that'd be great.

Ok, I missed it. I could not understand it from the article. Can someone tell me how the mixture is done? If I had to guess, it involves high pressure and heat.

  We report the spontaneous formation of an anomalously stable thin film of oil between droplets of water for polymeric oil. When there is weak adsorption of the oil on the water interface, the oil molecules at the interface become less compatible with the bulk oil, resulting in a weak attractive interaction between the two water droplets which induces a dramatic change in the dynamics of the oil molecules within the thin film.

That doesn't answer the question. It says what happens, but it doesn't answer how the researchers got the emulsion into that state.

They used one of these 50 mm diameter blades:

https://www.labunlimited.com/s/ALL/4AJ-9197006/IKA-R-1342-Pr...

Turning at 1000 RPM in a 55 mm diameter 250 mL beaker.

Silicone oils, liquid polyesters, and treated vegetable oil were examined.

None of their test oils were hydrocarbons. They were trying to form stable aqueous emulsions without using any additives, but some glycerol was involved. Not to mention Nile Red.

Meanwhile in the oil business, insane amounts of effort have been made for generations to try and break up these exact kind of emulsions. By using the smallest amount of additives and processing as possible.

This property of matter has been extensively studied from an entirely different "angle".

Now with samples of major cargoes of crude oil in the analytical laboratory, one of these smaller diameter blades is used in order to fit inside the neck of the official sample bottle:

https://www.multilab.ro/foto/ika/eurostar_60_digital.webp

All the water in the referee sample needs to be thoroughly mixed with the oil before you can withdraw a representative portion to certify the water content of the entire parcel.

Different oils have always been recognized as forming emulsions which separate at rates having wildly different orders of magnitude.

In the research area it was interesting to pursue the state-of-the-art in emulsion viscosity measurement decades ago, can't find a picture of a Ruska Viscometer but it wasn't good enough anyway, we had to design something completely different in addition. That was an expensive lab to build.

With crude oil in particular, you haven't seen nothing until you get a mercury-in-oil emulsion. Behaves like sand.

Oil and water can be very easily mixed into a vacuum.

https://www.youtube.com/watch?v=YJeWklggSpY

> Since most vegetable oils can be polymerized, combining them with water could allow researchers to make perfectly biodegradable polymeric materials.

Looks interesting, maybe it can replace a lot of plastics...

Any implications for oil-water getting in nature? Right now oil separates in water but what if there is oil that doesn't separate.

You can do this at home with a vacuum blender

Will this be another mass experiment? (i.e. when will the humanity learn to have balance of safe practices vs corporate greed, without self-serving bureaucracy and scientism)

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