Chemistry World Podcast -October 2011
1:05 -Microscopy reveals why ketchup squirts
5:07- Toyota create first magnesium-sulfur rechargeable battery
7:20-Paul Shearing explains why you might want to swap your home boiler for a fuel cell
14:30-Two for one - cleaning water and generating energy
17:52-Bacteria responsible for missing 'atmospheric brooms' that sweep the sky clean
20:19-How clean is your car's engine? John Bennett reveals what additives are in your fuel to keep your car running smoothly
27:21-High-throughput catalyst screening for the masses
30:46-Limestone is efficient energy distributor
34:00-Trivia - What's the fastest thing in the universe?
36:20 - It's our birthday! The Chemistry World podcast is 5 years old this month
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
Interviewer - Chris Smith
This month's episode has a lot of sauce (sound of sauce squirting). If you do not shake the bottle, none comes out and then allegedly a lot will. So what I've got here is some ketchup, now we understand a bit more scientifically about what's going on.
Interviewer - Chris Smith
That's the chemistry of ketchup being served up for you very shortly. Hello I'm Chris Smith. Welcome to the October 2011 edition of the Chemistry World podcast. With me this month are Phillip Broadwith, Laura Howes and Patrick Walter and also in this show, why homes in the future will have a fuel cell rather than a boiler and why limestone could become the energy currency of tomorrow.
(Promo)
The Chemistry World Podcast is brought to you by the Royal Society of Chemistry. Look us up online at chemistryworld dot org.
(End Promo)
(1:05 - Microscopy reveals why ketchup squirts)
Interviewer - Chris Smith
Ok, Patrick (sound of sauce squirting) if you do not shape the bottle, none comes out and then allegedly a lot will. So what I've got here is some ketchup, coming out quite well. So, now we understand a bit more scientifically about what's going on.
Interviewee - Patrick Walter
Yes so, when you pour ketchup out, it sits on your plate, it's quite solid, but then when you squeeze the ketchup bottle, it comes out quite fast like a liquid.
Interviewer - Chris Smith
Accompanied by the, sort of, farting you know, but I have got something which is a blob in the dish, which is not flowing like a liquid, now it's gone into the dish.
Interviewee - Patrick Walter
Yeah it's become almost solid, hasn't it?
Interviewer - Chris Smith
Indeed so why?
Interviewee - Patrick Walter
Right, well this is a behaviour they call, non-Newtonian liquid like. So in this case, the fluid is shear thinning, so as you apply more pressure to it, moves from a solid to a liquid state.
Interviewer - Chris Smith
So it's solid in the bottle. I gave it a shake and apply pressure, it became more like a liquid which is why it flowed up, then it settles in the bowl, there's no pressure on it now and it turns back to being a thick fluid again.
Interviewee - Patrick Walter
Exactly and people are also quite familiar I think with the shear thickening process, so perhaps you've seen in the Brainiac episode where they fill the swimming pool with custard and then John Tickle just ran across it, as he applied pressure to what was a liquid to start, it became solid and it could take his weight.
Interviewer - Chris Smith
What is actually going on, if we were to zoom in on this ketchup with a very powerful microscope and look at the molecules, why is it doing this interesting behaviour?
Interviewee - Patrick Walter
Right, it's probably best to start with what's the most popular theory for why this happens, now. So, at the moment they think the behaviour is a bit like a motor way, so the particles in the fluid in there, solid-like fluid are like cars on a motor way, so they move up and down normally. If it's a shear thickening fluid, you'll find that as you apply more and more pressure to it, the cars, it becomes a pile up, they crash, they all lock together and the fluid won't move, whereas in shear thinning behaviour, as you apply more pressure the cars actually just move faster along the lane, so it's like layer sliding across each other.
Interviewer - Chris Smith
I see and know you're saying there's some kind of revision of that theory or that someone's now got some new evidence that's not right.
Interviewee - Patrick Walter
So, Xiang Cheng, at Cornell University in the US has got an alternative theory. So, he used silica spheres in a water- glycerin mix and they followed what was happening when they applied different pressures to it using a confocal microscope along with a viscosity meter. So by watching it, they discovered that this kind of layer theory of the building up and the crashing of particles into each other wasn't quite right.
Interviewer - Chris Smith
And what do they say is happening instead then?
Interviewee - Patrick Walter
So, they say, for a shear thickening fluid what's happening is you are getting clumps forming together and as these clumps form together they're not lubricated enough to slide across each other and so they're clumping up and then you get this locking. So, like when corn flour, if you hit it too hard, it'll become solid. They're using things like corn flour now in things like body armour, very basic, exactly.
Interviewer - Chris Smith
The bullet proof vest. When the bullet hits, all the particles jam together.
Interviewee - Patrick Walter
Particles jam together.
Interviewer - Chris Smith
The fluid flows out from around them, they form a pseudo solid for a while which spreads the load.
Interviewee - Patrick Walter
Exactly, it spreads out a lot better than Kevlar does, because.
Interviewer - Chris Smith
So what about my ketchup then, what's going on with that? That's a shear thinning
Interviewee - Patrick Walter
So with shear thinning it's slightly different. So perhaps some of the listeners have heard a Brownian motion before. This is idea that.
Interviewer - Chris Smith
Brownian sauce motion.
Interviewee - Patrick Walter
(Laughs)With Brownian motion what's happening is the particle is all moving around, it's quite chaotic and they're bumping into each other. Although. It is just the natural movement of the particles. When the pressure is applied what's happening is you're reducing this chaos. You're overcoming the Brownian motion and causing the flow in a single stream, as is the case with the ketchup.
Interviewer - Chris Smith
So, flow becomes more streamlined.
Interviewee - Patrick Walter
Exactly and one another possible application of this is in things like industries. So if you're dealing with shear thickening fluids, it could be disastrous if they suddenly clump up. So, the more you understand the easier it would be to prevent such blockages.
Interviewer - Chris Smith
And the whole place now smells of ketchup and it will be for whole of the rest of this recording yummy.
(5:07- Toyota create first magnesium-sulfur rechargeable battery)
Interviewer - Chris Smith
Laura let's distract ourselves from the ketchup and talk about another way of getting energy. Let's talk about batteries.
Interviewee - Laura Howes
So, people will probably be aware of various metal ion batteries, lithium ion batteries being the most common example that's what is in your laptop and is also used to power cars. If you're in an electric car, then that's usually powered by lithium ion battery.
Interviewer - Chris Smith
Sure.
Interviewee - Laura Howes
But the energy density is not great, if you're in a car, then you've got to have loads and loads of them. It makes the car heavier.
Interviewer - Chris Smith
So most of the car is battery.
Interviewee - Laura Howes
Exactly, most of the car is battery.
Interviewer - Chris Smith
Not much for people.
Interviewee - Laura Howes
It doesn't.
Interviewer - Chris Smith
It does just to get the amount of energy you need to make a car practical, you need huge batteries, with the present electrode and electrolyte combos we've got.
Interviewee - Laura Howes
Precisely, so people are trying to make batteries smaller, more energy dense, you don't need quite as much and that's what some people at Toyota have come up with. They're actually, instead of using lithium ion they're actually looking at a magnesium-sulfur rechargeable battery.
Interviewer - Chris Smith
It's an unusual combination. Why are they going for that?
Interviewee - Laura Howes
The two electrodes, they match up in a really nice way with their energy levels, it means that they, you can get quite a lot of power out of them
Interviewer - Chris Smith
And presumably make them very small.
Interviewee - Laura Howes
And make them much smaller.
Interviewer - Chris Smith
And I sense an if coming now or a but.
Interviewee - Laura Howes
An if or a but the problem everyone's been like ah! This is theoretically a really good way of doing it, but to make a electrolyte which will work with the magnesium; it ends up degrading the sulfur electrode.
Interviewer - Chris Smith
And vice versa.
Interviewee - Laura Howes
Yeah. So it's a really good idea in theory but up until now, the electrolyte.
Interviewer - Chris Smith
They are not in practice
Interviewee - Laura Howes
The electrolyte has been the stumbling block.
Interviewer - Chris Smith
Have they solved it?
Interviewee - Laura Howes
They have solved it, but the problem is that at the moment, the electrolyte is nucleophilic and that's why it ends up attacking the sulfur. So take a non-nucleophilic organomagnesium halide, which involves magnesium and they also take a Lewis acid, combine them and it crystallizes and then they dissolve it back over and they get this large cobbled structure, that actually isn't nucleophilic, but allows the ions to transport across between the two electrodes.
Interviewer - Chris Smith
Is it practical though, will it work?
Interviewee - Laura Howes
I think it will, obviously Toyota think it will. Otherwise, they wouldn't be pursuing it. They don't quite know how long it's going to take to get it into a car, but they certainly think this is worth pursuing further.
(7:20- Paul Shearing explains why you might want to swap your home boiler for a fuel cell)
Interviewer - Chris Smith
Laura Howes. Now if you're thinking of replacing your domestic boiler, like I need to, why not consider installing a fuel cell instead you get heat, but then you also get to make your own electricity essentially for free.
Interviewee - Paul Shearing
I'm Paul Shearing. I'm an electrical and chemical engineering at University College, London and a Royal Academy of Engineering Research Fellow. There are a number of different fuel cells, but they basically all operate on broadly the same principles, which is what we call a redox reaction. So hydrogen oxidation reaction coupled to the oxygen reduction reaction can create a useful electronic current flow. And so we have catalysts, at the anode and the cathode side that catalyze these two reactions and also generates electricity in an efficient and also a very clean way. We're basically recombining hydrogen and oxygen creating this electronic current and the only emission from the fuel cell is water if we use a clean hydrogen fuel.
Interviewer - Chris Smith
Which is obviously a massive bonus because we're very worried about the environment and putting pollutants into it, but what are the big problems that people are struggling with? I mean, I remember, reading a bit of Jules Verne, where he talks about foreseeing the use of hydrogen and oxygen in fuel cells in the future and that was over a hundred years ago. What's holding the field up?
Interviewee - Paul Shearing
Sure, so I think William Gray was the first person to demonstrate the fuel cell principle in 1839. This has been hampered by a number of different things, although if you're going to Germany and California, you can find people using fuel cell cars, is that day to day run around in this country, especially, there isn't a huge fuel cell car markets and indeed the cars are unavailable. And I think one of the primary reasons of this isn't the technology behind the fuel cells, because we have this chicken and egg scenario regarding the hydrogen supply infrastructure. The companies who will provide the hydrogen refilling infrastructure are reluctant to implement this, if there's no market. There are no people driving the fuel cell cars to buy the hydrogen. Equally, there's no one that's going to buy the fuel cell cars unless there is the hydrogen infrastructure, so they can refill them. Here in the UK, we do have a number of privately owned filling stations, the first publicly accessible hydrogen filling station opened within the last couple of weeks and I hope they will see the demonstration programs that have been successful in California translates the UK market in the near future.
Interviewer - Chris Smith
Cars rob us a huge proportion of our hydrocarbon consumption in Britain, something about half of the fossil fuel burn in Britain is transport, but that means there's still a sizeable chunk of the pie, which isn't cars. So what else could fuel cells be used for to push down our carbon footprint and improve our environmental impact in Britain?
Interviewee - Paul Shearing
There are a number of different flavours of fuel cells that find applications in different areas. When we're looking at transport applications, we're normally looking at typically low temperature, we call it PEM fuel cells, that stands for Polymer Electrolyte Membrane fuel cells and these operate at temperatures 60 degrees Centigrade or so. They can be switched on and off very, very quickly and are ideal for these possible applications, but they do use a platinum catalyst, which is obviously very expensive. The other end of the temperature scale, we find fuel cells called solid oxide fuel cells and these are completely solid state devices, using ceramics and non-precious metal catalysts and because they operate in a much higher temperature regime, they can effectively catalyse the hydrogen oxidation and oxygen reduction reactions, using a much cheaper catalysis route. So, for example by replacing the platinum that you find in a PEM fuel cell with nickel in a solid oxide fuel cell; so, a much cheaper way around. However, because they operate at higher temperatures they have associated problems. They typically take a long time to start up in short time with a ceramic device, thermal cycling is often quite problematic and therefore they lend themselves naturally to stationary applications rather than transport applications. With the solid oxide fuel cell operating at say 800 degrees Centigrade; it may take a number of hours to start that fuel cell up from cold. Obviously this means that they're not so useful for transport applications, but they can be fantastic at generating high-efficiency low carbon energy for stationary applications and there's lots of industrial research and research in universities in UK and around the world in developing solid oxide fuel cells technology for stationary power generation , combined heat power generation as well in homes and on larger scale as well.
Interviewer - Chris Smith
What sort of efficiency can they achieve?
Interviewee - Paul Shearing
So, solid oxide fuel cells have fantastic electrical efficiency, but also they generate heat, which can also be usefully used in a home for example for hot water heating and so forth. So, on the top of this the idea is combined heat and power, so the combined efficiency of a solid oxide fuel cell would normally be, if we had a one to one heat power ratio, so for every kilowatt of electricity we generate, we generate a kilowatt of heat, we can typically expect efficiencies a ballpark figure of sort of 70% plus.
Interviewer - Chris Smith
Now we traditionally put big power stations and things away from settlements because they're big, they're noisy, they're smelly and they put enormous amounts of pollution up. Are you saying, based on the idea that this could be used for CHP combined heat and power that we're going to see a sort of return to microgeneration. We're going to see more little stations near settlements because they're much cleaner and they're going to be much quieter.
Interviewee - Paul Shearing
Absolutely. So, there are a number of companies developing combined heat and power units for the domestic market and the idea is that you would replace your conventional water boiler in your home with a solid oxide fuel cell, combined heat and power unit. So this would not only provide you with your hot water, but also with some of your electricity. This might not meet the full electricity demand for your entire household, but it means that you can dramatically reduce your energy costs and hopefully reduce your carbon footprint at the same time.
Interviewer - Chris Smith
I need to replace my old boiler right now because it's just blown up; sounds too good to be true. Why is this not being more widely embraced?
Interviewee - Paul Shearing
It is being widely embraced and there are a number of companies that are very actively developing this. There are a few who at the position where they're brining their product to market at the moment.
Interviewer - Chris Smith
And let me finish by asking you, how do you heat your home?
Interviewee - Paul Shearing
I'm afraid I'm still using a condensing boiler to heat my home. Condensing boilers are fantastically efficient technology for providing hot water and heating but one thing they can't do is provide electricity and with the solid oxide fuel cell combined heat and power system, you're in a position where you can take gas from the gas main in your house, which you would pay perhaps 3 pence per kilowatt hour and generate your own electricity which you perhaps pay 11 or 12 pence per kilowatt hour. So for that 3ps spent on gas, you got 12p of electricity. So there's a significant economic incentive as well as an environmental incentive. I would like to be one of the first to sign up to have the CHP system in my house when they're available.
(14:30- Two for one - cleaning water and generating energy)
Interviewer - Chris Smith
Paul Shearing from the University College, London and on the subject of two for the price for one, Phil's been looking at the clean water equivalent.
Interviewee - Phillip Broadwith
Okay well, this is kind of interesting. We're talking about solving two problems with one piece of equipment. We have contamination in waste water with various organic molecules that we don't really want to be in there, certainly want to process out before we can use the water again and then the other problem we've got an energy crisis coming. We need new sources of energy. So what Yanbiao Liu from Shanghai Jiao Tong University and his team have done is make a fuel cell that will solve both of those problems. It takes a little bit of sunlight, organic compounds from waste water and turns them into energy.
Interviewer - Chris Smith
So, the organic compounds are actually the energy supply? The sunlight effectively helps to unleash the energy in them.
Interviewee - Phillip Broadwith
Exactly right. So, just like you could burn these compounds to make energy, then you can feed them through a fuel cell to break them down, take some of the energy from the chemical bonds and convert them into safer by-products.
Interviewer - Chris Smith
In other words, the amount of energy that comes out is greater than you would get from solar alone.
Interviewee - Phillip Broadwith
Yeah absolutely. I mean, may be it's not. I don't know how it compares to direct photovoltaic generation, but it's not only generating energy.
Interviewer - Chris Smith
Because you're getting the water too.
Interviewee - Phillip Broadwith
Yeah you're getting the clean water as well.
Interviewer - Chris Smith
So how does it work?
Interviewee - Phillip Broadwith
What we have is a titanium oxide-nanotube-array. Titanium oxide is very good at taking in sunlight and that's coupled to a semiconductor electrode on the other side of the fuel cell. When the light hits the titanium oxide, it frees up electrons which go around the circuit and are injected into the side of the fuel cell. Those electrons then oxidize the organic compounds in the water, which breaks them down.
Interviewer - Chris Smith
Did they say which sorts of organic compounds they've tested because organic compounds are quite a broad term? We all know that some are more persistent than others.
Interviewee - Phillip Broadwith
Yes Chris. Well the ones that they mention in the paper are things like, sort of aromatic compounds, azo dyes, pharmaceuticals like, so if you take a paracetamol then a certain amount of that is going to come out into the water supply, personal care products.
Interviewer - Chris Smith
I'll think of oral contraceptive pills and HRTS as well, which we know has onward health effects and people are very worried about this because there's nothing in nature that breaks down these molecules because they're artificial and as a result, they tend to loiter for much longer.
Interviewee - Phillip Broadwith
Yeah, absolutely. I mean, I'm not entire sure, but those kinds of oestrogen compounds would be very susceptible to oxidation by this kind of direct electron injection.
Interviewer - Chris Smith
So, where do they see this working then? This is what a third world technology for countries where they can't afford to clean up water or are you saying that this could be deployed anywhere?
Interviewee - Phillip Broadwith
Well, I don't see any reason why it shouldn't be deployed anywhere. I mean, at the moment, waste water treatment is a relatively energy intensive process. If we can reverse that and turn it into an energy generation process, not only do we decrease our energy demand, but we're actually, you know, reversing that and supplying energy. So it's a double winning sometimes.
Interviewer - Chris Smith
Given the thing, as you said, it uses sunlight, which here at Britain, as we know, we cannot rely on this?
Interviewee - Phillip Broadwith
At the moment, this, as we say, this is a lab scale kind of project. It depends how far you get in terms of scaling up, as to how intense light works, but in the UK we do have solar photovoltaics that work perfectly well to generate electricity. So, it depends how much intense sunlight you need, but in principle there's no reason why you can't use it.
(17:52- Bacteria responsible for missing 'atmospheric brooms' that sweep the sky clean)
Interviewer - Chris Smith
We're talking of cleaning things up, well Patrick you've got something on the bacteria, which help us to keep the atmosphere clean.
Interviewee - Patrick Walter
Exactly. Hydroxyl radicals are what help to keep our atmosphere clean, . They react with lots of things like smoke and they clean it out of the atmosphere, break it down and just allow it to get washed down and cleaned up. So, atmospheric chemists have a bit of a puzzle. They know a third of the hydroxyl radicals come from nitrous acid, but they don't know where hardly any of this nitrous acid comes from. So, what it turns out now is they shouldn't have been looking in the skies above, but they should have been looking in so beneath our feet. So, beneath our feet, bacteria are making nitrite ions and these nitrite ions in the presence of water can change into nitrous acid and this nitrous acid can then partition and can turn into a gas that can then break down into these hydroxyl radicals in the presence of sunlight.
Interviewer - Chris Smith
How did they make that discovery?
Interviewee - Patrick Walter
Right. So what Yafang Cheng from Peking University in China and Hang Su at the Max Planck's Institute in Germany did was they took some soil samples, they put it in a Teflon coated chamber and they flooded it with synthetic air. They knew exactly what was in there and then they checked what was coming out the other side of the chamber and they're able to see that nitrous acid was actually coming out.
Interviewer - Chris Smith
And that was then all you need in order to get that to partition to become the air-borne form that then gives rise to the hydroxyl radicals then.
Interviewee - Patrick Walter
Exactly. Yes. I mean, we're quite familiar with the idea that plants need nitrite and many people think that some plants are actually able to produce these nitrogen compounds, but it's not actually the plants, they are things like clover, often referred to as nitrogen fixing but it is actually nodules within the clover's roots that contain these bacteria that produce these nitrogen compounds.
Interviewer - Chris Smith
So, what's the solution? We have to encourage more of these bacteria to grow in this soil?
Interviewee - Patrick Walter
So it's a big balancing act. This is another piece of the puzzle, so people can understand what's happening more. We need to know it's there so we can try to control what is going on.
Interviewer - Chris Smith
Patrick Walter.
Interviewer - Chris Smith
You're listening to the Chemistry World podcast with me Chris Smith. Still to come, a quick and dirty but very cheap way to discover new catalysts and new chemical reactions. When you need to fill up your car, should you buy the supermarket cheap stuff or pay a bit more for one of the big name brands, after all petrol is petrol, right? Well not necessarily because high grade fuels also contain agents to keep engines running smoothly into their old age.
(20:19- How clean is your car's engine? John Bennett reveals what additives are in your fuel to keep your car running smoothly)
Interviewee - John Bennett
My name is John Bennett. I'm the technical manager of fuel additives at Afton Chemical in Bracknell in the UK. The problems we're basically looking at are ensuring that the vehicles and their engines maintain the best possible efficiency and are kept in the best possible conditions, certainly as far as the fuel system is concerned. Our primary focus is on maintaining cleanliness. We specialize on the production of detergents which will help to either prevent the deposition or help with the removal of deposits that may in time reduce the efficiency and general ability of an engine to perform as it was designed by the original vehicle manufacturer.
Interviewer - Chris Smith
How long have people been putting detergents and other cleansants into fuels, John? When did this first come in?
Interviewee - John Bennett
Detergents have been around since the 1
No comments yet