0:00:01   Hi, my name is Seth Darling. I work at Argonne National Laboratory where I'm the director of the
0:00:06   Center for Molecular Engineering and I also direct an energy Frontier Research center called um use
0:00:12   advanced materials for energy water systems. And today I'll be talking about ways that we can use A.
0:00:18   L. D. And related methods to advanced water technologies. So we're all aware of just how essential
0:00:27   is water is in our daily lives. We all need it to survive of course and for sanitation and other
0:00:32   purposes. But in fact water is actually much more important to our society than you may realize from
0:00:38   this direct interaction we have with it every day. You need water to make just about anything. All
0:00:46   of the raw materials we use from paper to plastic to rubber, cotton all require tremendous amounts
0:00:53   of water to manufacture. What that means is that the goods that are made from these things, the
0:00:58   phone in your pocket, the clothes that you're wearing, the chair that you're sitting on. all of
0:01:02   these things require tremendous amounts of water. So as the world continues to develop, each
0:01:09   individual's water footprint is growing dramatically. Even electricity requires water to generate.
0:01:15   So demand is skyrocketing around the world and yet supplies are under increasing threat due to
0:01:22   climate change, unsustainable use, pollution and so on. So As you can see from these projections
0:01:29   published in the New York Times back in 2019, water stress is all over the place and it is expanding
0:01:36   going forward and we'll continue to do so. This is literally one of the biggest threats we face as a
0:01:41   society Over the next century or two. Okay, now there are all kinds of things we need to do to
0:01:48   address those challenges involving policy and infrastructure and so on. But there are also many
0:01:53   opportunities for science and technology to address these water challenges and many of these science
0:02:01   and technology opportunities come down to water solid interfaces the place where materials meet
0:02:08   water or more generally Aquarius fluids. This is what controls the performance and properties of
0:02:14   membranes and sensors ands orbits and issues like fouling. So many of the underlying component
0:02:22   technologies in water treatment processes rely on what happens in water solid interfaces. At the
0:02:29   same time, water solid interfaces are rather poorly understood. There is this wonderful quote from
0:02:36   the great scientist Wolfgang Pauli, who said God made the bulk surfaces were invented by the Devil.
0:02:43   And this is because, you know, while there's still plenty to learn of course about bulk solid
0:02:48   materials in bulk liquids fluids, there is much more to be learned about the interface between them
0:02:53   because it is so much more complex where those bulk properties become disrupted for both the solid
0:02:59   material and the fluid. This is actually the mission of our Energy Frontier Research Center, amused
0:03:06   where we have a collection of fantastic researchers from Argon National Laboratory where it's
0:03:10   headquartered a number of faculty members from the University of Chicago as well as some from
0:03:15   Northwestern University. All focused on this question of water solid interfaces and trying to
0:03:20   understand them more clearly in terms of absorption and reactivity and transport and ultimately how
0:03:26   that understanding can deliver better technologies. So I'm gonna give you examples from my own group
0:03:34   where we use primarily tools like L. D. And related methods to manipulate these interfaces, these
0:03:40   water solid interfaces. And we're gonna start with some examples from the world of membranes.
0:03:44   Membranes are one of the wonderful ways in which and treat water but they are particularly prone to
0:03:52   the scourge of fowling. Fowling is basically where stuff dunks up on a surface and this is
0:03:58   ubiquitous and water systems. Water systems are notorious for fouling membranes are particular
0:04:03   challenge in this context, because of course, membranes are porous materials and you need water to
0:04:08   transport through the membrane in the context of water treatment. And so as those pores get dunked
0:04:13   up with stuff, of course, it is harder for the water to pass through and ultimately it won't at all.
0:04:18   And one of the most problematic Fallon's is oil and particularly oils like crude oil, which tend to
0:04:24   stick very aggressively to surfaces and follow them up. So you can see that as an example here,
0:04:32   here's pictured a piece of a polymer membrane. This is a commercial polymer membrane with some crude
0:04:39   oil on it. That's that black blob there in the center. And as you'll see when this is submerged
0:04:44   under the water, the oil remains firmly adhered on that interface, it won't come off. You can rinse
0:04:48   it and backflow and so on. It will not release from the surface. If you take that same polymer
0:04:55   membrane and tailor the interface using A. L. D. But not changing the poorest nature of the material
0:05:04   so it can still perform a separation. You can see here. The difference in its resistance to fouling
0:05:10   the crude oil on the surface just lifts right off leaving behind a pristine membrane. So why does
0:05:16   this happen? Well, here's some snapshots from some molecular dynamics simulations performed by a
0:05:22   collaborator at Argon. Uh Subaru, pictured in the corner where they've taken some amorphous slabs of
0:05:29   various metal oxides. And here we're picturing aluminum oxide, titanium dioxide and tin dioxide uh
0:05:35   with water liquid liberating over the surface and dynamical fashion. And you can see just by eye
0:05:42   from these snapshots that the aluminum oxide has very little water near the interface. But the
0:05:46   titanium and tin oxides have these tightly bound hydration layers. You can see it as well here in
0:05:52   the correlation functions on the right Where there are actually two tightly browned hydration layers
0:05:57   on both the titanium and tin oxide and only very weakly bound water with the aluminum oxide. And
0:06:03   it's actually that tightly bound water that delivers this fouling resistance. Because the water is
0:06:10   bound so tightly, the oil cannot actually touch the oxide and therefore it can never foul it or not,
0:06:16   never, but will be less prone to fouling it so released so much more easily when it's just exposed
0:06:20   to some water. Now, what I was showing you was some static videos of kind of uh gently placing a
0:06:29   fouled membrane in in water. The question is, can this actually prevent fouling during a real
0:06:34   filtration or separation process. And here I need to introduce the two geometries, the two common
0:06:40   geometries used infiltration to better understand these experiments and these are dead infiltration.
0:06:46   Which is what we most often do in research labs where you're pushing the entire feed stream down
0:06:53   through your membrane with of course, hoping to filter out the things that you're trying to target.
0:06:59   That is actually not typically the way that filtration is done in industry, the way it's done much
0:07:04   more commonly in industry as so called cross flow filtration, where the feed stream is running
0:07:09   parallel to the surface of the membrane and the trans membrane pressure is sufficient enough for the
0:07:15   in this case water to pass through the membrane and the salutes to be blocked. The reason that cross
0:07:20   flow is usually used in industry is because that sheer force associated with the tangential flow
0:07:25   will tend to remove these Fallon's that might get stuck on the surface or at least remove some of
0:07:32   them. Now, I'm going to show you an example using debt infiltration. The reason for this is because,
0:07:37   as I just described, fouling occurs much more aggressively in a dead end system, so it's easier to
0:07:42   probe your anti fouling technology um, when fouling is happening more aggressively. So what we have
0:07:50   here is a dead end cell with a crude oil in water emulsion, which you can see picture being pushed
0:07:56   down through the membrane and in this case the oil droplets and that emotion are larger than the
0:08:02   poor side, so they get filtered out as you can see in the feed and permeate solutions there. The
0:08:07   problem is, as you can see pictured on the right, the flux of water going through this polymer
0:08:13   membrane plummets very rapidly because of fouling with the oil. And even if you rinse it with water,
0:08:19   you get no recovery of that flux again because it has been fouled. But if you take that same
0:08:26   membrane and replace it with one that's been coated with one of those eld oxides that has the
0:08:31   tightly bound hydration layers, you get very different performance. You can see here with this tin
0:08:36   oxide that the flux will still decline because it's in a dead end geometry. And we're just kind of
0:08:42   collecting oil droplets near the surface. But when you rinse this with water, you recover your flux
0:08:47   because it's not actually touched the oxide. It's not fouled the interface and it will just rinse
0:08:52   right away. So really simple treatment for that interface that can give you a significant
0:08:58   improvement in performance. Now, that might get you really encouraged about what L do can L. D. Can
0:09:05   do for membranes but there is a catch here which is that commercial polymer membranes are made from
0:09:11   many different chemistries. Many different polymers. This is not an exhaustive list here, but these
0:09:16   are some of the most common polymers used to make membranes. And some of these polymers have
0:09:22   functional groups that are good at binding those LD precursors to give you a nice coating on your
0:09:27   interface. Things like poly ether cellphone for example, which has the cell phone groups or maybe
0:09:32   the carbonell groups you might find uh and some other polymers. But many of the most common polymers
0:09:38   used to make membranes like P. V. D. F. Or polypropylene have no such functional groups. There's no
0:09:44   way to easily new create an L. D. Con formal coating on these membranes and thereby you can't get
0:09:50   all of these advantages that I showed you in that previous example. But we've developed a pretty
0:09:57   simple solution to this problem which is to use one step before you do the A. L. D. And that is
0:10:03   dipped coding in a solution of a molecule like tannic acid. So tannic acid is pictured there it
0:10:09   looks like kind of a complex molecule. It's actually a naturally occurring uh compound that's found
0:10:14   in tree bark and other places. Uh And tannic acid is not particularly unique or magical here. It's
0:10:22   just an example of a molecule that has the features we're looking for which is minorities that will
0:10:27   bind to those types of polymers that don't have the right functional groups like polypropylene or P.
0:10:32   V. D. F. Because it is hydrophobic uh minorities. But it also has functional groups like carbonell
0:10:38   groups that will bind the L. D. Precursors. So it acts as kind of a bridge between the membrane and
0:10:44   the L decoding. So you can take your A P. V. D. F. Membrane, simply dip it in a solution of tannic
0:10:49   acid and then proceed with A. L. D. Like normal. And you should be able to get all of that same
0:10:54   functionality I showed. But now with basically any pollen remember. So here's an example of a bunch
0:10:59   of little coupons of polymer membranes that have been dip coated in tannic acid and then with
0:11:07   various numbers of A L. D. Cycles. And the brown color you see is indicative of the oxide coating
0:11:13   forming on the on the membrane. You can see in the pristine column the left most column that even
0:11:19   after, you Know 50 or 70 eight LD cycles, you're barely seeing any oxide forming on the surface
0:11:24   because again there aren't inherently binding groups for the L. D. Precursors on this membrane. But
0:11:31   even with a modest pre treatment with tannic acid, we can start getting good L. D. Codings with
0:11:36   relatively low numbers of cycles and you take those same pieces of membrane, you just dunk them in
0:11:41   water because remember what we're trying to do is to create that hydra filic surface that will bind
0:11:46   protective water layers. And here you can see that while the native membrane doesn't really get wet
0:11:52   easily by water. With a simple pre treatment with tannic acid, just a few A. L. D. Cycles will start
0:11:58   making your membrane hydra filic. And so just like before you can put these into a dead infiltration
0:12:05   cell in this case the gray data are from a membrane that we tried to code using A. L. D. But did not
0:12:11   pre treat and you get that big drop influx that does not recover. Whereas the one that's been pre
0:12:16   treated so therefore has a good l decoding on it. Now has this beautiful recovery of flux with water
0:12:22   rinsing just like we saw before. Now that's a really effective way to extend the operational
0:12:30   lifetime of your membrane and a fowling environment. But it will still ultimately failed because
0:12:35   that is an example of what's called a passive anti fouling strategy meaning it's just trying to
0:12:40   prevent Fallon's from touching the surface. At some point they will and once they have nuclear
0:12:46   waited on the surface they can spread you'll lose that protective hydration layer and the membrane
0:12:51   will become fouled. So to be more aggressive ultimately you're going to need something that will
0:12:57   break down those felons degrade them into smaller pieces that will then go back into the water. And
0:13:03   one of the great ways to do that is using potala sis. One category of which is photo callouses.
0:13:08   We're using light to drive the reactions. So infotech Attallah sis, you're shining your your light
0:13:13   on generally a semiconductor generating electrons and holes. And when you're in water in an inquest
0:13:20   environment, both electrons and holes will react with that water and species in the water to produce
0:13:26   a variety of reactive species like super oxide radicals, hydrogen peroxide. Um the holes can create
0:13:34   hydroxyl radicals for example. And these all will attack organic substances like oil and break them
0:13:42   down into smaller fragments and ideally all the way down even to basically fully mineralized carbon
0:13:49   dioxide and water. So if those organic substances or Fallon's, that will cause them to detach from
0:13:57   your surface. Now, one of the most common, probably the most common photo catalyst used in this
0:14:04   context is titanium dioxide. And that's because it offers all kinds of really great advantages. It's
0:14:09   earth abundant. It's nontoxic. It's stable and water of course, that's important here. And it's very
0:14:13   effective at creating reactive oxygen species roos even under ambient conditions, you don't have to
0:14:19   heat it up or apply pressure or what have you. There is though, one drawback to titanium dioxide and
0:14:26   that is that it requires an ultraviolet light to activate it because it has a relatively large band
0:14:31   gap about three electron volts. That means you need UV light and that doesn't mean it's useless. You
0:14:37   can of course use UV lamps and this is done. But that increases the expense. And also makes it more
0:14:43   difficult to use in, say, developing world applications where you don't necessarily have access to
0:14:48   electricity, let alone ultraviolet lights. In that case. What would be really nice is if you could
0:14:54   get the same type of functionality of T I O two but with visible like and what would be really great
0:15:01   is if you could even use sunlight which of course is free and plentiful. So how do you take catalyst
0:15:09   like T. I. 02 and make it sensitive to visible light? One of the great ways to do that is with
0:15:14   doping and one of the dough opens that's particularly effective in this regard is nitrogen. You can
0:15:20   just put a little bit of nitrogen into your T. I. 02 and that will make it sensitive to visible
0:15:25   light because it places states in the gap. So you can see pictures here of three membranes. Uh
0:15:31   pristine membrane on the left, one that was coded by A. L. D. With regular T. I. 02 in the middle
0:15:37   and then one with the doped T. I. 02 on the right. And by I you can see that that membrane with the
0:15:43   nitrogen doping has this sort of yellowy orange color which tells you it's absorbing visible light.
0:15:49   And the U. V. Spectra here confirmed that where you're picking up this whole part of the kind of the
0:15:53   blue into the green part of the spectrum. Whereas the regular tho to only absorbs out in the in the
0:16:01   ultraviolet. So now you can take a membrane like this and just shine visible light on it sunlight or
0:16:06   simulated sunlight and perform focus palaces and water. So here's the concentration plotted, for
0:16:12   example of just organic molecule and water over time with light shining on the membrane system. In
0:16:20   water with just the starting membrane you get no degradation of that organic. But with the nitrogen
0:16:27   duty I owe to you can see this nice photo catalytic activity where it's progressively degrading the
0:16:33   organic species in the water. And you can use this to make a membrane that will actively degrade
0:16:39   foul in such that it can be self cleaning. So here again, we're plotting the flux of water going
0:16:44   through the membrane over time. And we're starting with the lights off because we don't want any
0:16:48   photo ca palaces to happen at the beginning here And there are two membranes whose data are plotted
0:16:54   here, one that we coated with regular T. I. O. Two and one that's been coated with nitrogen doped T
0:16:59   I. 02 So we have some initial water flux in these membranes. And now we're going to intentionally
0:17:05   foul them. We're introducing a protein here called bovine serum albumin, which is known to stick
0:17:10   aggressively to these membranes. And you can see the flux drops significantly at some point when
0:17:16   we've dropped it down to, you know, somewhere, say below half of where it started or so. Uh we
0:17:21   remove that talent and we reintroduce clean pure water. And here you can see there's no recovery in
0:17:28   the flux because this is truly foul. This is a irreversibly fouled membrane, it wasn't just kind of
0:17:34   loosely attached to the surface. Now, all we do is turn on the lights. And what you can see is
0:17:42   there's this phenomenal recovery in the flux from the nitrogen doped sio two just with visible light
0:17:48   shining on the membrane. This is in situ in in Operandi even in the filtration cell that this is
0:17:54   happening now, that's a severely fouled membrane that is showing self cleaning. Of course, in most
0:18:00   real filtration processes, you're not gonna have that much foul and present, it will be. There is
0:18:04   more of a dilute or trace contaminant in your in your feed stream. So, here's maybe a more realistic
0:18:12   setting where we've given it just a constant exposure to the foul UNt. But at a lower concentration.
0:18:17   And as you can see here, as long as you keep the lights on this nitrogen doped sio two membrane can
0:18:24   stabilize its flux higher than 95% of its original flux value, more or less indefinitely. I'm only
0:18:30   showing five hours here, of course. But um you can see it's it's gotten flat and in principle this
0:18:35   could have an indefinite operational lifetime under this type of a fowling environment. As long as
0:18:41   the lights are on.
0:18:45   Here's another application for membranes. This is a photo from a wastewater treatment plant. And if
0:18:51   you ever go to a wastewater treatment plant, you'll see a lot of tanks that look like this. This is
0:18:55   an aerobic digestion tank and that frothiness you see on the surface because of a bunch of bubbles
0:19:01   that are being added to the tank through aeration generation process. The reason they had the
0:19:07   bubbles is because there are microbes living in the water that degrade the pollutants that are in
0:19:12   the water and their metabolism is such that they're feeding on all of this waste. They need extra
0:19:17   oxygen to keep going there aerobic microbes and so they have to add that oxygen in the form of air
0:19:23   bubbles through the water in order to keep it working effectively. And this is a huge energy expense
0:19:29   in water treatment. It's actually the largest energy consumption in one of these plants. As these
0:19:34   aeration in the aerobic digestion tanks. So if you can make those that aeration process more
0:19:40   efficient, there'll be a huge energy efficiency gain in water treatment. And the way you make
0:19:46   operation more efficient is to make the bubbles smaller because a smaller bubble has more surface
0:19:51   area to volume ratio. So more of the oxygen will get into the water and not release at the surface
0:19:56   back into the atmosphere. So to make smaller bubbles, we're going to make a special type of membrane
0:20:04   called a Janice membrane. Janice membrane is one that has different properties on its two faces,
0:20:09   like the roman God Janice. And there are many different ways to make Janice membranes and they're
0:20:14   useful for many different types of things. I'm just going to show you an example here from
0:20:18   generation and specifically we're going to make a type of Janice membrane where the properties are
0:20:24   moving in a Gradient from one face to the other. Now those properties can be any two different
0:20:29   properties positive charge or negative charge. Hydrophobic city and hydra Felicity or what have you.
0:20:35   Okay. Uh in this case we're going to be playing some tricks with the A. L. D. To not get a perfectly
0:20:42   can formal and uniform coding throughout the poorest membrane material but rather to create a
0:20:47   gradient by getting the right um diffusion conditions for the L. D. Precursors going down through
0:20:55   the porous material. So here you can see a cross section of a porous membrane uh where the blue over
0:21:01   laid on the micrografx. Here is the aluminum signal going down through that cross section. And you
0:21:07   can see the gradient there with your I. Uh And what's cool with A L. D. Is that you can actually
0:21:12   tune the shape of that gradient. We can make it steeper by using more L. D. Cycles like you're
0:21:17   seeing here. Or we can even move kind of the location of the curve down through the depth of the
0:21:23   membrane by playing with for example, pressure or temperature. So we have really arbitrary control
0:21:30   over the shape of what that gradient looks like of the inorganic material going down through the
0:21:34   member cross section. Just to show you can actually make a Janice membrane this way here's the same
0:21:40   membrane top and bottom and you can see the water droplets on the backside which was not coated. Uh
0:21:46   You still have that hydrophobic city where the water balls up and on the front face where we exposed
0:21:51   it to the metal oxide. We now have a hydra filic surface where the water droplets spread out. So why
0:21:58   did we do this? The idea is we're gonna pressurize air up through the column, into the water through
0:22:06   the membrane and in the native membrane which is hydrophobic everywhere. Uh It's also arrow filic.
0:22:13   It likes air so as the air bubble starts to come up through the poor in the membrane, it's going to
0:22:17   spread out on the surface of the membrane which likes the air more than the water. And so you're
0:22:22   gonna end up with this really big uh bubble of air that will eventually release from the surface
0:22:28   when it has enough buoyancy from being big enough. The idea of the Janice membrane is we've made
0:22:33   just that top surface there hydro filic so that now is the air starts to come out of the membrane.
0:22:39   Water will undercut it because it's hydra filic and sarah phobic and then it will release when it's
0:22:44   a much smaller and here I'll just play them side by side. You can see the polymer membrane on the
0:22:50   left before it was treated has these very large bubbles. And the one on the right that we've turned
0:22:55   into a Janice membrane now releases very small bubbles, thereby giving you more oxygen in your water
0:22:59   for the same energy input. Mhm. So let's move on to our next example outside of membranes now into
0:23:08   something called steam generation. And most of the folks working in this field of steam generation
0:23:14   talk about this in the context of desalination through distillation, which may very well be a useful
0:23:20   and very interesting technological application. Uh one that really motivates me in this field is a
0:23:26   little bit different, which is pictured here. This is evaporation ponds at a mining operation. This
0:23:32   is an aerial photograph, there are buildings and roads and in the shot there to give you a sense for
0:23:36   scale. These are huge evaporation ponds, very common in mining operations are also in hydraulic
0:23:43   fracturing operations, where you get massive amounts of waste water generated in the process and
0:23:49   that water is filthy, it has salts in it, it might have radionuclides, it can have organic materials
0:23:54   and all kinds of stuff which make it not safe or legal to dump it into a waterway or in many cases
0:24:01   to re inject it back into the ground. So instead, what they have to do is just wait for it to
0:24:05   evaporate. And this is a huge challenge in in all of these industries because evaporation is slow.
0:24:13   Much of the heat involved with the sun shining down on these evaporation ponds is just lost to the
0:24:18   surrounding environment not going into evaporation. The question is, can we make that more efficient?
0:24:23   So, in an evaporation or even distillation process very energy intensive. Because you're heating up
0:24:29   this huge bath of water takes a huge amount of energy to break all those hydrogen bonds and then
0:24:34   ultimately drive it into the vapor. And if you're distilling it, you'll of course then re condense
0:24:38   the purified water. The idea here is you're using a plentiful renewable source though sunlight. So
0:24:45   it's not pulling energy off the grid, but we still don't want to heat up the entire bath of water
0:24:49   because again, that'll get lost to the surrounding environment. What we want to do instead is to
0:24:54   place a material at the interface. The air water interface, that is a photo thermal material that
0:24:59   will convert light to heat very efficiently. And the idea then, is all of that energy gets focused
0:25:07   right where it needs to be, where the evaporation happens at the air water interface. But you need
0:25:12   that material to do lots of things. It's got to absorb a big part of the solar spectrum, efficiently
0:25:17   convert that light to heat, prevent the heat from being lost down to the water bath below. Its got
0:25:22   to transfer the heat to the water to evaporate it at the interface. You need water to transport up
0:25:27   through it. So it's got to be porous, effectively needs to be buoyant so it floats on the surface.
0:25:32   Obviously it has to be water stable and you saw the scale on that picture, it's better be low cost
0:25:37   and scalable or what's the point here? That's a lot of requirements for material. But it turns out
0:25:43   folks are finding lots of ones that work Well, one that we've discovered works well. It's actually a
0:25:47   very old material, chinese calligraphy ink which is just a natural material made by burning wood
0:25:52   under certain conditions and formulating it with some other natural materials. And you can get this
0:25:57   nice black material that can be coded easily on surfaces. You can see here the chinese character for
0:26:02   for water under thermal imaging with sunlight shining on it gets quite hot. Not surprisingly,
0:26:08   because it's black. It's a carbon nano material. But there is one thing that this chinese ink
0:26:15   doesn't have, which is water stability. In fact water is the solvent and in chinese things. So of
0:26:19   course it's going to disperse in water. So if you were to take some porous material code on your
0:26:25   chinese ink, put it on the water. It just dissolves back off the surface and disperses. So here's
0:26:30   where L. D. Can come to the rescue again, you just coat your porous material with the chinese ink.
0:26:35   It can be a membrane, a sponge piece of fabric. What have you would even works and then you overcoat
0:26:40   it with an optically transparent metal oxide film, like titanium dioxide, for example, that
0:26:47   encapsulates it and secures it on the surface so that it won't disperse when it's placed in water.
0:26:53   And you can see how effective this is here. Here's beakers of water with thermal imaging. One just
0:26:58   on the top row is just a beaker of water that gets kind of lukewarm when exposed to sunlight.
0:27:02   Whereas if you put one of these photo thermal l destabilized materials at the top, you get all that
0:27:08   thermal energy focused right where you want it to be at the air water interface, big jump in
0:27:13   temperature and much faster evaporation of water for the same energy input. So this can dramatically
0:27:19   increase the efficiency of this process. The last example I want to show relates to another way to
0:27:26   treat water which is orbits and specifically the one we want to target here is oil spill pollution,
0:27:34   huge challenge. This is a photo from deepwater horizon, but of course oil spills happen in water
0:27:38   bodies all the time. There have been many major ones just this past year and literally thousands of
0:27:43   them happen every year of different scales and most of the soil never gets cleaned up. That that
0:27:49   does is most often just burned in place, turning a water pollution problem into an air pollution
0:27:54   problem. What would be great as if you could have absorbent that would selectively soak that oil up
0:27:59   out of the water and then it will be even greater as if you could reuse your absorbent because
0:28:06   otherwise you'd have to have enough of it to scale to the size of the spill, which is of course
0:28:09   completely impractical. And something like deepwater horizon, you want to be able to capture the oil,
0:28:14   recover the oil and then reuse this orbit and keep going back for more. So here we're going to use a
0:28:20   variant of L. D. Called sequential infiltration synthesis for those who aren't familiar with it. Uh
0:28:27   The idea here is you're dealing with a substrate that is porous to the L. D. Precursors, like a
0:28:32   polymer. The space between the chains is as uh sufficient for the molecules to diffuse through. So
0:28:40   instead of kind of the millisecond and military type pressures and times you use an L. D. With
0:28:45   little pulses that might form an inorganic film on top of your polymer substrate and S. I. S. We use
0:28:52   typically larger times higher pressures. So the integrated exposure is much larger and allows those
0:28:58   precursors to diffuse down into the polymer film. And if you have functional groups that will bind
0:29:03   them, you can form a composite material. And classic example is try method aluminum and water just
0:29:11   like an L. D. But with a polymer with functional groups that will bind the Try method aluminum like
0:29:15   carbonell groups that you might find in something like PM. Emma. And you can see here in this cross
0:29:20   section of a P. M. A film, you can actually grow aluminum oxide in this case inside of the film
0:29:25   rather than as a coating on top of it. Okay, so here we're going to take a polymer like polyurethane,
0:29:32   which you might be sitting on right now. It's used in seat cushions, which does not like oil more
0:29:37   than water. In fact like oil and water about the same. We're going to do S. I. S. On this to grow a
0:29:42   metal oxide uh down into all those little fibers that make up the phone. And then we're gonna use
0:29:49   that as an anchor for a silent ization reaction to attach molecules that have the properties that we
0:29:55   want in this case being Olio filic, oil loving and hydrophobic water heater. And I'll show you a
0:30:02   video here where you can see this uh in action. We've got a uh sponge that we've treated in the way
0:30:10   I just described. And this is oil and water. We just died. The oil blue to make it a little bit
0:30:16   easier to see and hear is an oil spill. A small one, admittedly. And you'll see what the sponge can
0:30:22   do it selectively and rapidly grabs the oil. So that's great because it was only a filic. You wanna
0:30:28   be able to recover the oil, which is easy by simply squeezing it. And then as I said, you want to be
0:30:34   able to reuse yours orbit, which you'll see right here. And the beauty of this uh technology is that
0:30:41   you can do this over and over again. Uh you can just keep squeezing it like a kitchen sponge and
0:30:46   reusing this orbit repeatedly. We actually don't know what the limits on reusability here are
0:30:52   because unfortunately, Ed the postdoc here gets tired of doing this experiment before we see any
0:30:58   drop in performance. So certainly dozens or 100 times maybe even more than that. We can't say for
0:31:04   sure. Now we have scaled up this technology for testing at a tank like this and I'm just going to
0:31:11   show in the interest of time to videos side by side. Uh, we'll start with the one on the right.
0:31:16   We've actually taken this olio sponge as we call it out onto the open ocean and the pacific ocean.
0:31:22   There's a place where oil leaks out of the sea floor naturally and forms a sheen on the surface of
0:31:27   the ocean, which you can see there, that kind of rainbow pattern. And you'll see in a moment a big
0:31:32   pad made out of that olio sponge, which we drag across the oil sheen and it'll pick it right up off
0:31:38   the surface. Um So this works out on the open water and oil sheen by the way is almost impossible to
0:31:45   clean up. Otherwise you can see the oil on the surface of the pad on the left. Now, if you look at
0:31:51   that video, you can see a whole bunch of those pads which have been submerged under the surface of
0:31:57   the water. That is a cloud of crude oil being exposed underneath the water in the water column, as
0:32:04   it's called, exposed to a big wall of olio sponge for a period of time. And then that crane you see
0:32:11   picture there is used to lift that wall out of the water. We can take the pads then off of their
0:32:17   frame, put them through this ringer and squeeze out the fluid that was captured. And the question is,
0:32:22   do we actually get any oil? Of course, you'll have some water in the sponge because it was submerged
0:32:26   in the water. But did you actually get any oil? Which is a different physical challenge than
0:32:31   cleaning oil off the surface And you can't tell him that shot. But here in the next one, you can see
0:32:37   that is brown water coming out of there because we did in fact pull oil out of the water, um which
0:32:43   was the first ever example of cleaning crude oil out of the water column. So we're excited about
0:32:48   that, showing you examples from membranes and catalysts and solar steam ins orbits. But there are
0:32:54   many other ways in which controlling water solid interfaces can help with water technologies that I
0:32:59   didn't have time to talk about sensors and fighting corrosion and so on. Again, it all comes down to
0:33:04   these water solid interfaces and L'd and related tools are a great way to come call them. Whole
0:33:10   bunch of folks contributed to the work that I showed you hear the one individual I really want to
0:33:14   highlight as my colleague and friend, Jeff Allam, who for my money, is the best LD scientists in the
0:33:20   world. And I'm really lucky to have him as a as a longtime collaborator uh and he worked on pretty
0:33:25   much everything that I showed you here today. Funders are along the bottom of the screen and with
0:33:31   that I want to thank you so much for your attention finished in learning more about water. Feel free
0:33:35   to check out. The only book ever written by three sevenths Water is available from booksellers near
0:33:42   you. And the website for our Energy Frontier Research Center is pictured there. Thanks so much.