hey everybody today we're going to be
seeing what happens if you powder eyes
Orbeez so if you've been living under a
rock for the past few years and you
don't know what Orbeez are they're made
of what's called a super absorbent
polymer so that when you stick them in
water they grow to an extreme size so
they suck up all the water around them
and they can grow to about a hundred
times 150 times their original size
until they're around 99.9% water so when
the super absorbent polymer is around
this size of beads you have to leave
them in water for a few hours to get
them to grow to the large size but if
you have a small powder if it happens
extremely quickly let me show you this
is actually the filling that's in
diapers so this white powder is the
exactly the white powder that's in
diapers that absorbs urine now watch
what happens when I pour in this water
look at that so that tiny little bit of
powder just absorbed all this water you
can see the gel here so now it's just
this thick gel so all of that water has
now been absorbed in fact it could
actually absorb a lot more water than
what's here now but an interesting thing
happens when we put salt on these super
absorbent polymers that have absorbed a
lot of liquid so let me sprinkle some
salt on this
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so you can see now I'm just kind of back
to a liquid on my plate it's not a gel
anymore at all so what that salt did is
it sucked the liquid back out of the gel
so basically these little tiny crystals
now that I put salt on it the water
actually went the other way instead of
going into it it came out of it and the
reason is due to the change in the
osmotic pressure so you can see now I
just pretty much have pure water again
oh now it's leaking off my thing so you
can see my super absorbent polymers are
no longer super absorbent so here's what
osmotic pressure means so I have just
regular water in this beaker here and
then I have just a plastic cup that I'm
going to poke holes in now place it
inside of here
and so there the two heights of the
liquid are exactly equal right now the
liquid inside the cup and the liquid
outside the cup are exactly equal but
then watch what happens when I put just
a little bit of this super absorbent
polymer and the smaller cup in the
center
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you can see after a few minutes now how
the liquid level in the center cup now
is much more than the liquid level
outside of it and that is due to the
osmotic pressure so it continues to suck
the water up even though it requires
more pressure to do so and the reason it
does that is due to the attractive
nature of the super absorbent polymer
chains with the water molecules so
basically it can withstand that higher
pressure because it's more attracted to
the inside of the cup than the outside
of the cup so basically we could use
this to measure the osmotic pressure of
different materials so if you put
different polymers in there and it
absorbs water the higher it goes up in
the cup the higher its osmotic pressure
is so I have two balls here where I put
Orbeez in at the same temperature in the
same time one of the balls just had a
tap water and the other one had salt
water the same salinity as the ocean and
you can see how after about an hour
these aren't full-grown yet but you can
see how big these are compared to the
ones in the salt water so these are
barely grown at all so what that means
is that if you pour this polymer in salt
water then it will absorb water and the
water that it absorbs will have less
salt in it than the water around it and
then you could actually squeeze the
water out of that gel and that would now
be a way to reduce the salinity of water
however the maximum amount of salinity
rejection was around 67% in the studies
i looked at and that's not even
comparable to osmosis or distillation
but what they like to use it for is a
pretreatment for osmosis or distillation
and it's much cheaper than both of those
processes but what this means is let's
say you're stranded in the middle of the
ocean and you don't have any water but
you do have a bag of Orbeez that means
that if the salinity of the specific
ocean that you're in is not too salty
maybe around two and a half percent or
less you could stick your Orbeez in the
water and let it absorb as much water as
it can and then you could squeeze the
Orbeez out and the water that comes out
of the orby should have less salt in it
than the saltwater and then you let the
Orbeez dry
and then you could repeat that process
over and over and over again but the
problem with doing this is somehow you'd
have to be able to squeeze the water out
of the Orbeez and the pressure needed to
squeeze the water out has to be above
the osmotic pressure so it has to be
higher than around 10 bar 10 atmospheres
so basically you'd have to have a press
on board and be able to press that out
and squeeze out that water in order to
get that fresh water out of it so even
though Orbeez and the super absorbent
diaper pail more powder are essentially
very similar Orbeez take a lot longer to
absorb liquid but most likely it's
because the Orbeez are so much bigger in
size so they have a lot smaller surface
area to volume ratio but if we could
increase their surface area they'd
probably act a lot more like this diaper
powder here so let's try to see if we
can increase their surface area to
volume ratio so the way I'm going to do
that is I'm going to try to blend up
these Orbeez in a blender and make a
powder out of them and then put them in
water and see if they react as fast as
this stuff so during this experiment if
you ever try this at home you have to be
very careful because this stuff absorbs
water so well you don't want to breathe
it at all because if it goes in your
lungs it's going to stick to your lungs
and absorb the water in your lungs so
you don't want that to happen all right
so let's try to blend up our solid
Orbeez
okay now let's see how fast they react
when we put it in water oh man okay
let's see what happens when we put our
or B powder in this bucket of water here
3 2 1
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whoa look at this it's becoming just
solid almost instantly that's crazy this
feels almost dry now so let's see what
happens when we put salt back on these
Orbeez
then once again it turns it back into
this liquid state again so you can see
how dry they were before and now how
liquidy they are basically it's just
like water with chunks in it now look at
this that's crazy how the salt can have
such a great effect on how much water
these polymers absorb so what's
happening here is the salt is basically
sucking the water out of the super
absorbent polymers because the salt now
has a higher osmotic pressure than the
polymers themselves and so what it looks
like on a diffusion basis is it looks
like there's a lower concentration of
water outside of the polymer now and so
it moves from this high concentration of
water out to the lower concentration in
the salt water hey everybody thanks for
watching another episode of the action
lab I hope you enjoyed it if you did
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