Chemists discover water microdroplets spontaneously produce hydrogen peroxide | Hacker News Reader

Chemists discover water microdroplets spontaneously produce hydrogen peroxide

phys.org

138 pointswglb59 comments

Wow. Wonderful stuff. >1ppm is suprising! Dr. Cooks group is working on microdroplet catalyzed reactions as well. Reactions happen magnitudes of order faster in these conditions: https://cen.acs.org/articles/95/i46/Microdroplets-rev-chemic... https://aston.chem.purdue.edu/

I wonder if this could be a nontrivial, alternate explanation for the erosion of materials in turbulent flows (ship propellers are a great example).

If so, it could change the way people design and manufacture these components.

There would be implications in the maritime and hydrocarbon industries, as well as in hydro power.

Explains well the title of "Universal Solvent" if so.

It’s been a long time since this has made headlines. Last time it was microcavitation. Has that been debunked?

Great point. What I’m suggesting is that, based on the article, perhaps there’s an alternate or (more likely) supplemental explanation to microcavitation.

Maybe the baby bubbles bursting apply both exert a physical and a chemical (per the article’s discovery) effect on the substrate. If nontrivial, applying/developing different coatings that are more resistant to h2o2 could be useful in real world applications.

I really don’t know, but it’d be a logical next step for applied research!

Wouldn't someone have noticed the chemical corrosion – even if not specifically looking for it?

Isn't cavitation a pretty well understood phenomenon? If something else was going on, wouldn't the models be incorrect?

Honestly I wouldn’t know, just musing! My background definitely isn’t in fluid flow.

A quick search suggests that cavitation modeling is actively being updated (src: https://aip.scitation.org/doi/10.1063/1.5052257), but I don’t know to what degree they’re refining them. Not my area of focus.

I wonder what peak concentration can be reached by cycling pure water through a micro-sprayer. I'd be skeptical if this could make rocket fuel, but it would be extremely cool if it could.

Turning ice asteroids into usable fuel would make space much more accessible.

Rocket fuel... I assume you mean hydrazine? You need more than just water/hydrogen peroxide for that right? (Like ammonia?)

concentrated hydrogen peroxide, if exposed to a catalyst splitting it up again, makes viable a viable thrust source for rockets.

Right, spray it through a platinum screen, and oxygen gas is liberated.

Silver screen would work too. Iron oxide would work... Many other substances would catalyze peroxide with various degrees of efficiency.

I'm not sure what modern peroxide rockets use, but the steam generator in the V2 used sodium or potassium permanganate.

For an in-depth and interesting explanation of how that works, I enjoyed this video:

https://www.youtube.com/watch?v=EgiMu8A3pi0

Includes a demonstration of the potassium permanganate and hydrogen peroxide at around the 52 minute mark.

Indeed. Used today for the attitude control thrusters on the Soyuz reentry capsule and as a monopropellant for the gas generators on the Soyuz booster rocket.

And for motorcycles https://www.youtube.com/watch?v=4oV-GW4O4bI&feature=youtu.be...

hydrazine is N2H4 -- a different fuel

https://en.wikipedia.org/wiki/High-test_peroxide

I took rocket fuel to just mean fuel rockets use. Some of these include highly refined kerosene (RP-1), methane, hydrogen and yes, hydrazine. The point was to ask if these microdoplets could be used to propel a rocket.

If you can get low concentration H202 you can get dangerously high concentration H202 by applying a fan (H20 evaporates faster).

One suspects that electrolysis to get H2 + O2 would produce more rocket fuel with less energy. It's a much more direct process.

Might still have applications for cogeneration though.

Maybe this is a dumb thing to ask, but would these microdroplets also evolve H2 gas then?

I think you must be right, the hydrogen doesn't vanish. So this could be a way to produce H2 has without electrolysis.

I guess you'd get little H2 out of it while pumping the water all the time, it would be less energy-efficient than electrolysis.

I suspect you'd be right, but thats not for granted.

Who need pump when the rain does that for you.

For the record, I'm wrong. Hydrogen peroxide is H2O2, so it's just adding an extra oxygen from the air to the water molecule. I was thinking about Hydroxyl which is OH and would cause excess hydrogen gas.

That... seems to me to depend on whether the process is internal (within the droplet) or external (between the droplet and the external environment, which presumably contains oxygen). If it'd internal, the hydrogen has to go somewhere, so probably; if it's external, it could just be capturing extra Oxygen somehow, so maybe not.

But I am not a chemist.

I'd be interested to see whether the effect increases in a pure oxygen atmosphere, or goes away in pure nitrogen. Really, just try a bunch of different nitrogen/oxygen mixes. Maybe you can just oxygenate the shit out of bulk water and get the same effect.

The O2 test is mentioned in the abstract: "Changing the spray gas to O2 or bubbling O2 decreased the yield of H2O2 in microdroplets"

The H ions would likely dissolve and lower the pH of the water

You need H+ to raise the pH, like when you split water in HO- and H+. [1]

In this case they get H2O2 (neutral) so the H must be neutral, so they must combine to form H2 (neutral). (Perhaps the H radical can survive some time in water until it combine with other H and form the H2.)

[1] A small technical detail is that the reaction is 2 * H2O --> H3O+ + HO-, not H2O --> H+ + HO- , but H+ is the usual shorthand.

I agree, the news article shows that when they accidentally stumbled on this property they did the extra effort to further investigate (for example size of droplets). I have not yet read the actual paper, but I would at the very least expect the hydrogen to be traced to rule out other hypothetical explanations.

For example suppose the sprayer was a metal through which hydrogen can diffuse, perhaps sucked in osmotically, with the OH somehow stuck at that point on the metal surface, then over time all the surface "pores" would be clogged, but the bulk metal still osmotically sucks hydrogen, so perhaps the OH's on the surface are forced to recombine into H2O2 to make space. (I think their explanation is much more likely than mine, but it illustrates the importance of tracing all the chemical end products, to make sure the reaction is happening where one thinks it is happening. essentially: perform the experiment again in a continuous mode, in a closed recipient while monitoring hydrogen concentration. Continuous mode to prevent hydrogen gas diffused in metal components to be outgassed by say temperature effects of thermal cycling)

I think their explanation is very likely though. That the concentrations were higher in smaller droplets is a strong indicator that this is a surface effect (since volume of a droplet scales down with the third power in radius, while surface area scales down only with a second power in radius). Then remember that water is a polar molecule, and if they are anything like magnets, they don't like being parallel, so I would expect the electric dipole of a water molecule to try to lay in the plane of the surface on average, but as we all know, you cant comb a hairy ball!

This sounds similar to Fleischmann–Pons 'Cold fusion' in 89 [0] (Could be related as the 30th anniversary?). It would be great if we could easily spit water to hydrogen and oxygen (unlimited clean fuel), but it comes down to those pesky chemical bonds, it takes a LOT of effort (energy) to pull them apart.

[0] https://en.wikipedia.org/wiki/Cold_fusion Hopefully, someone can find a good video covering it.

Makes me think of Hawking Radiation: Something pinging into existence at a small scale due to the hidden fizziness of the universe.

Um...hasn't this been known for at least a century? I'm confused.

Are you confusing H2O2 with the OH- and H3O+ ions found at a ~10^-7 concentration in water?

This is fascinating. Does it mean vaping, or more generally inhaling pure water vapor, can be unsafe?

That is not what it implies at all.

It might be true anyway, but this is not the cause.

Could you elaborate on it please? It seems vapes create particles of comparable size to what is reported here. Also inhaling H2O2 can be toxic beyond a certain concentration. But I'm not sure what is the concentration here. The last paragraph is interesting though:

>Zare said, and it could lead to simpler ways to disinfect surfaces—simply spraying water microdroplets on a table or floor might be enough to clean it.

It means:

"I have to stretch the possible immediate practical applications of my research in order to better secure interest/funding/publicity, it's just part of the job"

Pretty much every every article like this has a couple sentences on practical applications that sound revolutionary. It's just part of how things are done and most of them will never come to fruition. Don't take it too seriously unless they have a proof of concept.

Someone mentioned the concentration was >1ppm. In other words, measurable, but negligible.

Vaping being bad for you is more directly comparable to smoking. You are inhaling hot water vapor and a bundle of chemicals into sensitive lung tissue. We've known that smoking is bad for you for decades. We don't really need new science to explain vaping.

Would this include nebulizer output? I wonder if it has an antiseptic effect.

Two men walk into a bar.

One man orders H2O.

The other says: "I'll have H2O too".

The second man dies.

Always reminds me of the limerick that ends “what he thought was H2O was H2SO4”

Not a limerick, though it has a similar feel. The way I originally heard it was:

    Once there was a chemist
    There isn't any more
    What he thought was H2O
    Was H2SO4.

I've heard a few variants, such as "Bobby was a chemist" or "There isn't one no more". At least one blog[1] claims the original poem from 1894 is:

    Our Willie passed away today,
    His face we’ll see no more;
    What Willie thought was H2O
    Proved H2SO4.

[1] https://www.barrypopik.com/index.php/new_york_city/entry/joh...

I've always heard it as:

    Billy was a chemist's son
    But Billy is no more
    For what he thought was H2O
    Was H2SO4.

and I heard it as:

  Little Timmy took a drink    
  But he will drink no more    
  For what he thought was H2O    
  Was H2SO4

I went down a bit of a rabbit hole with this yesterday. It's interesting--there's clearly some parts of the poem that are effective and lasting, while other parts aren't.

"thought was H20 was H2SO4" is identical in all the variants I found after the mid-20th-century. Most, but not all, have "What he thought was H20 was H2SO4". It seems like they "perfected" that part and it hasn't really changed since.

But the rest is very changeable--a few variants mention chemists and most mention a male name of some sort, but most have nothing else in common.

Two scientists walk into a bar. "I'll have H2O," says the 1st. "I'll have H2O, too," says the 2nd. Bartender gives them water because he is able to distinguish the boundary tones that dictate the grammatical function of homonyms in coda position, as well as pragmatic context.

https://twitter.com/dianeturnshek/status/939155156645699584?...

Two Nobel laureates walk into a bar. They order Bud Lights because they've got nothing to prove. ;)

As she notes in the thread, the original author appears to be here: https://notallwugs.tumblr.com/post/93075748270/two-scientist...

I Thought this was already known? I remember hearing about this in my Undergrad physics classes. At any time in liquid water, there are hydrogen bonds constantly breaking and rejoining between H-O, H2O, and H2O2.

Do you mean OH, H2O and H3O?

https://en.wikipedia.org/wiki/Hydronium#Determination_of_pH

Heh, that's probably it. Thanks for the reminder.

>simply spraying water microdroplets on a table or floor might be enough to clean it.

$5 the next homeopathic "fad" is going to be water sprayers that cure ebola.

Dr. Gerald Pollack has studied the "fourth phase" of water, which are sheets of H1O1. Water in this phase is electrically negative and forms the surface of bubbles/droplets, vesticules in cells, clouds, plasma in blood, & drives movement of water in plants. This book explains a number of phenomena with models backed by experiment.

https://www.amazon.com/Fourth-Phase-Water-Beyond-Liquid/dp/0...

http://moreisdifferent.com/2015/11/19/debunking-exclusion-zo...

Useful list of papers. The effect appears to be real. Over-sure blogger admits it at the end.

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