Graphene: The perfect water filter

<...perfect water filter...>

Oh yeah? To what particle level? Will it do down to ion level, like RO? And how is it cleaned/backwashed/flushed of ions? Will it physically withstand osmotic pressure?

Arrrrrooooooooogah!

Yeah, and a few years down the line we'll probably find its toxic.
Nano this, graphene that... has any of this stuff actually produced anything useful yet?
Del

RO is far from perfect. In theory it may be perfect, but the reality is that no membrane is constructed without some small imperfections that will let in some percentage of undesired particles and microbes.

The statement is false on the face of it. Filtering "stuff", at least stuff that does not react chemically with the filter, depends on the size of the atom or molecule. Water is neither the largest, nor the smallest of the molecules the graphene filter may encounter.

Additionally, any atom and ion in solution is smaller than an intact molecule, like water. Hence, they will be passed. Chlorine or Fluoride in the clean output water for anyone?

Additionally, graphene is a new and different form of carbon. While I think I know, what activated normal carbon filter's particles do in the body of a person (not much, activated carbon dust is a medical item for absorption). On the other hand, the fragments of graphene are close to atomic level, quite a different animal. I bet dollars to donoughts, that it will be found surprising, deleterious and poisonous in some cases. Translation: we do not know diddly squat. What about investigating before assuming?!?

Chlorine or Fluoride in the clean output water for anyone?

Pretty sure that in the UK both of these are added during the treatment phase anyway. Fluorided water is why we Brits have such wonderful teeth these days!

I can tell when the treatment plant's got a problem because my water (cold water from mains) stinks of dilute bleach.

Agree on the other points: magic like this is rarely used for good in the first instance.

Maybe it is added. But IS IT RIGHT? That is the subiect of chemistry, not common habits of adding this or that crap, isn't it?

Put on your thinking cap,girl, sheesh!!!

I think you need your comprehension cap on, boy.

You asked:

Chlorine or Fluoride in the clean output water for anyone?

And I pointed out that in the UK, we already have those in our drinking water. My point - the one you patently missed - was:

Why worry about removing chlorine and fluorine if you're only going to add it back in?

The debate of whether it is right for a government to insist on a disinfectant and a tooth decay inhibitor being added to the public water supply, whatever their other effects, is not for this thread. Quite frankly, the question is probably moot, since they've been doing it for so long.

Get a grip, grab an iced tea and chill out!

I may not have been applying laserlike clear logic with unavoidable conclusions piercing thru your frame of mind.. My shortcomings in persuasion is in that sense.

Rose, I do not give a flying fig about customs, habits and such, when my question is about the periodic table. That is basic science, basic chemistry.

The elements on the edges of the table are the most aggressive. Li, Ka,....Cl, Fl.

I do definitely question of their uses for sound reasons.

Customary, habitual? Get real.

The most aggressive of elements win over others in the free radicals game, all the time, every time.

The ball is in your court now.

Customary, habitual? Get real.

Customary and habitual.

Almost the entire united states uses chlorine as a disinfectant in the water supply.

Almost the entire united states uses fluoride as a dental addition

Population, 2010, 308,745,538 pretty common even

You are correct in stating the facts, that water is chlorinated to disinfect, and fluoridated to supposedly improve teeth integrity in the population.

Wikipedia goes back to a half century to a century old science and public hygiene decisions. Review and revisions are long overdue, as neither the science, nor the circumstances on the ground remain the same over a century, or some such.

I will summarize bare essentials of chemistry here, as relevant.

1,. In plain basic chemical reaction a more aggressive element tends to substitute itself in the compound, knocking the lesser out. In the halogen series it is: Iodine, Bromide, Oxygen, Chlorine, Fluoride, toward the more aggressive species.

1.1,. In a folded protein (a normal state) only atoms visible from the outside are exposed to this substitution. Atoms folded in are shielded and invisible from the outside.

2,. Life developed a fiendishly complex way controlling most of the trouble arising handling Oxygen. Chlorine is handled right only as salt solution NaCl, nothing further, as far as I know. I am not aware any way handling Cl, Fl in biological systems safely. They exist only to wreak havoc in biochemistry.

So, the governments are behind the eight ball, as usual.

I welcome your remarks. But historical remarks are iust, well, historical only.

For further reading go to Wikipedia: (free) Radicals, chlorination, fluoridation (tendentios presentation), ozone.

I had heard no disputes about chlorine as a water disinfectant, and in fact chlorine in liquid or tablet is still recommended for emergencies, survival, natural disasters and such.

Fluoride I had heard of disputed use as a water additive going back to my childhood. Yet we seem largely to still use it.

I have no background to allow me to judge whether these are good decisions, and only took exception to your apparent dispute of the terms common and normal.

If I misunderstood, please forgive me.

As for arguments about whether fluoride is eating our braincells or causing cancer or such, one has to make very clear, factually driven arguments with evidence lest one get tossed in with folks who oppose other such usual and customaries, like immunization. Another subject I am not technically qualified to judge, but make an exception based on the other positions people who take this particular position also posses.

So as a layman, really all I can do is ask if there is evidence, ask who is making a claim, ask what their motives may be, and then ask what other claims they are making.

"If ya got too many feathers around your butt, I think you may be a duck."

Does bacon kill you? Yes. Does bacon kill you substantially earlier than you might have died otherwise? Maybe and depends. See what I mean?

How else does a layman defend themselves from the constant barrage of folks who would have you live on air and hover above the ground lest you stomp a microbe or impact the planet?

You are right in the customary use of chlorine (mostly in the hypo... form), Emergency and survival use I wholeheartedly subscribe to. Most anything is better than a, say, typhoid fever.

Your body's defense system uses digestive enzymes to get rid of trouble, but most remarkably it uses ozone in the form of high concentration hydrogen peroxide! Invaders and undesirable particles either digested, or oxidized to hell, by a highly reactive form of oxygen. The price is high in ancillary damage, but the body knows how to dispose of the garbage produced.

My point is to do the cleaning of water first, then remove the organochlorides (cancer causing), or treat the water with ozone, remove the traces of it. Use the water with an absolute minimum of sterilizants. Example: silver, a few atoms per particle. No bacteria is immune to it. No known biological problem to you. Not fully researched to be used on entire populations. But oxygen=ozone form is. Let's get modern.

My other point is, that the 4 most aggressive elements have no (practically) use in biological systems.: Li, Ka, Cl, Fl. I have a fundamental problem with that, if somebody pushes otherwise.

That is what bothers me in the prattle about Fluoridation. Way to long on verbiage, way to short on basic chemistry. "We always did it that way" is way underwhelming.

Ahh, see?!

Now you sound like a nice reasonable person. Can't be starting a subject like that in the middle as it were.

I used to spend WAY too much time at the library reading books on waste water treatment as a young man (I was strange), and it did not take me long to figure out that (much like school busing in pursuit of educational equality) there were good solutions and there were 'established' solutions and they didn't always meet.

Silver is an option not much used, copper another recently revealed; but still few and far are the water treatment facilities that use oxygen and sunlight despite the combination being cheap and effective. But chlorine is cheap and effective (cheaper) and offers a legally defensible position.

A little liability / tort reform would totally change the United States.

But then I used to drink from mountain streams - so what do I know?

Not asking you for asking with any particular reason, Ed. Long time back I read that storing water in (open container) in the fridge was good. For reasons that completely escape me, it was/is suppossed to somehow cause chlorine to 'evaporate'. Does this ring any bells with anyone ?

As mentioned, very unusual for the UK, my part of the world does not have flouridation. I have not noticed any evidence of worse dentician than other parts of UK. My thoughts on the whole topic are neutral, though the water does pong on occasion. I suspect weather and pressure causing crud to be loosened in the pipework. Most of our water is from boreholes thru chalk. This buggers my kettle, but cause me to wonder what it does to my guts (gallstones or such perhaps?).

I am aghast - this is a worthy topic of discussion, yet the majority of the world does not have pure water. My possible kidney stones or rotten teeth are as nothing compared to how many have to live. Seeking how to help various people get potable water is surely one of the best things an enginering community can do

/pompous comment

In the fridge works, any tap water releases chlorine and 24 hours or so produces notable differences, but the fridge is not required.

......good job....there's some nasty looking green stuff lurking at the back which I'm not brave enough to touch . So called Filter Jugs are big business, but I question if they are worth it (new filter every month etc). Can't recall any tales of people dying (UK) from drinking water straight out the tap.

Folks used to live remote, and water came direct from a hillside stream with no filtering other than a settlemant tank. Risk of dead animals and all sorts. Repeated testing proved it to be purer than the nearest mains water supply. I suspect a margin of luck, though I've met many people living off similar supply for years with no adverse effect.

Mrs K is one of those who swear that tea tastes better with fresh boiled water. I simply re-boil whatever is in the kettle. General advice is not to do so for making baby milk formula (I guess it concentrates whatever nasties). Does boiling get rid of any of the nasties such as chlorine?

Minor (and irrelevant detail); Keeping a jug in the fridge, if it has spare room, makes the fridge more efficient. Cold air doesn't flood out each time you open the door.

This ramble is purely so I can say Smeg on forum .

It's always recommended to let water stand for 24 hours when changing the water in a fish tank - even for goldfish. Partly to get the water to room temperature and avoid thermal shocks to the fish, but also to reduce the chlorine content. So don't put it in the fridge if it's for the fish....

At which point did I make reference to or denigrate your excellent application of the periodic table?

You suggested by implication that no-one would want either Chlorine or Fluorine atoms (ions) in their drinking water. I applied a dose of practicality and pointed out that many water treatment organisations (barring Etherville) add both of these to the mains supply for health reasons. I ask again, why would we worry about removing them when making potable water?

OK this assumes you're not trying to make potable water from over the counter Chlorox, but if it's present in those concentrations you are going to spot it.

Theory is wonderful. Practical makes living possible.

It has been proved many times that these additives improve the younger population's teeth and make them less affected by various illnesses that teeth can get.....

You have a choice.

If you don't want to drink it then buy bottled water.

When you look at the graphine through an electron microscope do the holes look like the heads of little Micky Mouses?

I'm missing something here.

It says that it allows water vapor to pass through. So it doesn't sound like you can just pour water through it and have it purified.

Doesn't distillation accomplish the same thing...............with or without a sheet of graphene?

Maybe it has an application in chemically contaminated water, but as far as turning sea water into fresh, or removing minerals.......................I think we've already figured that out.

But no heating required as I understand it.

The comment:-

In another experiment, Dr Nair & Co. sealed a bottle of vodka with the graphene filter. This allowed just the water to evaporate, effectively distilling it into super-vodka.

was really interesting!!!

Just what Russia needs. ;-)

Oh right. My thinking was backwards.

I was thinking along the lines of water purification................but it seems like the more practical application, would be in the removal of water from other substances.............like vodka. Yikes!

Given that ethanol is more volatile than water, the result of the stated experimental evaporation is quite surprising.

It wouldn't be, if the material were discovered to be so selective as to allow water to pass through, and ethanol not, in the liquid phase.

Maybe all is not what it seems.