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A manufacturing process that produces long strips of high-quality graphene

news.mit.edu

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Re: A manufacturing process that produces long strips of high-quality graphene

#51

Post by TeMPOraL »

jws wrote: post #16
ChuckMcM wrote: post #13

One of the applications for graphene membranes that I am watching for are large scale desalination plants. It has been shown to work for small membranes and if you had enough surface area you could build a desalinator that was using not much more energy than the energy to pump the water around.

It looks like maybe a factor of 3 or so energy efficiency improvement is available for desalination. Current efficient processes are around 3kWh/m³†. The thermodynamic limit is about 1kWh/m³‡. That can be improved a little if you pump more seawater, there is a tradeoff there. Treatment of fresh water is around 1kWh/m³, so it gets into the ballpark for freshwater treatment, though I presume some of the freshwater trea…

Wow, that's a great presentation.

I wonder how one can stumble upon more presentations/summary reports like that on current state of other globally important issues.

Re: A manufacturing process that produces long strips of high-quality graphene

#52

Post by TeMPOraL »

aoner wrote: post #39
chiefalchemist wrote: post #18

How would you dispose of this stuff? I presume it doesn't decompose. Mind you, there's not high volume any time soon. I only curious about lifecycle.

Why dispose them? They’re a great carbon sink and as long as we don’t make short graphene chains I think they’re also not toxic for the environment. The process described uses methane (greenhouse gas) and if the process would be done with renewable energy it could even perhaps be carbon negative?

Good point. Could it be e.g. reused as a structural element, or some kind of filling (e.g. for roads)?

Re: A manufacturing process that produces long strips of high-quality graphene

#54

Post by aoner »

TeMPOraL wrote: post #52
aoner wrote: post #39

Earlier quoted context omitted.

Why dispose them? They’re a great carbon sink and as long as we don’t make short graphene chains I think they’re also not toxic for the environment. The process described uses methane (greenhouse gas) and if the process would be done with renewable energy it could even perhaps be carbon negative?

Good point. Could it be e.g. reused as a structural element, or some kind of filling (e.g. for roads)?

Yes, there are some papers that suggest that adding graphene-like elements to for example concrete will make them stronger. I think that if we can find a carbon neutral process of creating graphene it could be a great additive and a carbon sink (finally making a useful product out of carbon). It can even be used to detect damages in concrete (electrical resistivity value reduces at maximum compressive load). Here is an interesting paper: www.mdpi.com/2071-1050/9/7/1229/pdf but there are more applications once you start looking.

Re: A manufacturing process that produces long strips of high-quality graphene

#55

Post by agumonkey »

bigger_cheese wrote: post #49
AChamarthy wrote: post #21

Earlier quoted context omitted.

EU's biggest research initiative is the Graphene Flagship - https://en.wikipedia.org/wiki/Graphene_Flagship Major Conferences - Graphene Week, Mobile World Congress (Barcelona + SF), National Graphene Association (inaugural conference was Oct 2017) Major universities in the US - UT Austin, UPenn, MIT, Stanford, Rice, Berkeley. Lot of activity in Korea, Japan, and China Companies - Various companies on growth side. Lo…

My Materials Engineering Undergrad thesis (in 2010) was on synthesizing graphene for Li-Ion battery applications. It was interesting stuff at the time but I haven't kept up with the research. Our lab was using ESRP (electrostatic spray reductive precipitation) I'm sure by now a lot of other better techniques. All I can really remember from my thesis was I had a throwaway line describing graphene as a single layer of…

there an english dude on youtube, robert murray smith, he setup a "little" lab then factory to produce storage using graphene or close. Caps and the likes. Do you know him ? I wonder how good he can be with his reduced size operation.

Re: A manufacturing process that produces long strips of high-quality graphene

#56

Post by fudged71 »

DubiousPusher wrote: post #27
fudged71 wrote: post #26

Earlier quoted context omitted.

Not viable, graphene isn't strong enough.

Sources? Googling only returns a bunch of random threads with people insisting it's possible.

Graphene has a break length of 4000 km (the length were it will break simply under it own weight) and a space elevator needs to be 35000 km long.

Re: A manufacturing process that produces long strips of high-quality graphene

#57

Post by nine_k »

marcosdumay wrote: post #43
hcknwscommenter wrote: post #40

Earlier quoted context omitted.

I'm not sure I understand how you arrived at your first point. It seems to me that at a suitable temperature and oxygen content atmosphere, it should burn about as clean as natural gas. Why would you expect otherwise? I also do not understand your second point. Surely, it is oxygen that is the missing ingredient in the burn rather than water vapor. What does water vapor provide to increase the rate of combustion?

About the first point, you are expecting total combustion of a solid. That is hard to achieve. By your theory coal should also burn cleanly, and it evidently doesn't. With enough temperature and a high oxygen pressure, graphene will burn cleanly. But also will your furnace, and my bet is that both will do so at roughly the same temperature and pressure. About the second point, oxygen does not react well with graphite…

Coal has lots of other stuff mixed in to carbon: notably sulfur, and up to 10% of non-burning minerals (ash), often containing significant amounts of radioactive uranium and thorium.

Pure carbon (as in graphene) should burn much more cleanly, provided abundant oxygen.

Re: A manufacturing process that produces long strips of high-quality graphene

#58

Post by MertsA »

DmenshunlAnlsis wrote: post #45
MertsA wrote: post #37

Earlier quoted context omitted.

Oddly enough yes Helium has a smaller atomic radius because the additional proton and electron complete that first electron shell and get pulled closer to the nucleus.

Helium is a strange bird. Every other element in liquid form will freeze if you drop the temperature enough, except Helium. You must greatly pressurize Helium for it to freeze. It is worth pointing out that while the atomic radius of Helium is smaller than Hydrogen, Helium is still the heavier element. It’s small radius and tendency to remain a gas or liquid makes it very useful in testing for leaks or as a purging g…

That's an understatement. Helium cooled below 2K loses literally all viscosity and will flow through porcelain like it's a sponge. Not only that, because there's literally zero viscosity, convection makes superfluid helium a great heat conductor. All of this was discovered back in the 30s. The man who discovered superfluid liquid helium must have truly thought he had gone insane.
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