(Lightly edited for readability)
Speakers: Sujit Ghosh, Writakshi Mandal, Subhra Priyadarshini
00:01 Sponsor announcement: This episode is produced with support from DBT Wellcome Trust India Alliance.
00:25 Subhra Priyadarshini: There's an abundance of resources in nature, sometimes hidden away from plain sight. Renewable energy resources, however, are shrinking, as we know. And scientists constantly try to figure out if there are new sources to tap into. Uranium is one such element that is used to power nuclear energy. It is normally extracted by open surface mining in India or through a process called in-situ leaching from the sub-surface like in the US, Australia and Kazakhstan.
Recently Sujit Ghosh and his team from the chemistry department of Indian Institute of Science Education and Research Pune made headlines by extracting a record amount of uranium from a relatively new source – from seawater. They made a haul of 28.2 miligram of uranium in 25 days using one gram of a new adsorbent material, which they call an ionic macroporous metal–organic framework of MOF.
Now countries around the world have been trying to make a breakthrough in uranium extraction from seawater. Sujit and his team have designed this efficient material that has exceptional selectivity, a record capacity, ultrafast kinetics, and long service life to extract uranium from natural seawater quite affordably.
In this episode of the Nature India podcast series called “I am a Scientist and this is where I work”, join me, Subhra Priyadarshini, as I take a deep dive into the depths of the ocean to understand this cutting-edge research. The workplace I am going to describe may not appear unconventional to you at first – what’s unconvetional about a chemistry lab, you might ask. But the application of chemistry to potentially solve the world’s energy crisis surely is off beat. Keep listening, as we hear from Sujit Ghosh about this new benchmark uranium adsorbent made in his humble chemistry lab.
02:57 Sujit Ghosh: So here we have synthesised a material which can extract uranium in record amount compared to any other materials reported in the literature. But if you see the amount of uranium present in mines, that can go for maybe next 100 years. But if you think, what about after 100 years, uranium in mines is going to be finished and then fossil fuel, that is going to finish within next couple of decades or so. So that is the importance of this research.
03:24 Subhra Priyadarshini: Right. So sea water contains about three parts per billion of uranium. So there's an estimated minimum of 4 billion tons of uranium in the world's sea waters. That makes it about 500 times the amount of uranium we get in land based uranium ores. How have you taken it a step ahead, advanced it, with this new material?
03:49 Sujit Ghosh: Yeah, people saw the potential of uranium in seawater in 1960. My lab started from 2009 here and this is one material we are making – it is called metal organic framework, relatively new wonder material. In fact, this material development started only in the last two decades and took us almost like one and a half year to complete measurements. So, we got seawater from Juhu Beach in Mumbai. And then we checked the efficiency of this material in our laboratory, we are really excited that this material has real potential.
04:26 Writakshi Mandal: The compound which we have prepared in lab is very unique. It can absorb uranium from deionised water as well as from natural seawater in the same way. We collected the natural seawater from the coastal area of Arabian Sea. Actually, three people went there to collect the water. We went there in the middle of November and the weather was very sunny. Approximately 40 gallons of water we collected. Due to the huge amount of water, we rented a car to go to Pune. In our laboratory, we placed all the water in a big drum, filtered the compound to remove all the dust and waste, and then put our compound. And after 30 days, we measured the amount of uranium.
05:19 Subhra Priyadarshini: That was Writakshi Mandal, a PhD student in Sujit’s lab. So, let's take our listeners into your lab and the action that takes place there so we can understand the journey of the seawater and how it finds its way into a chemistry lab to be broken down and then to reveal this massive energy potential.
05:42 Sujit Ghosh: In the chemistry laboratory, you see a lot of bottles, you see assays, different solvents, chemicals and then of course, we have lot of instruments. Chemistry is like cooking. Now, just mix many things and then cook something, but then in this case, since these are small molecules, we cannot see exactly what we have made. So, now to check that we have big instruments to which students take those materials, go to the instrument room sit there collect data, again come back to the lab, sit on the computer and then analyse those data. Single crystal X-ray diffractometer, powder X-ray diffractometer, we check porosity measurement, BET surface area instruments, TEM measurement, SEM measurements – let's say, we do many measurements at IIT Bombay. We also did some theoretical calculation with the help of some collaborators and then we did experiments in the laboratory for several months.
06:42 Subhra Priyadarshini: Three parts per billion – must be challenging to extract this ultra-low concentration of uranium in this very high salinity of seawater that also has high abundance of interfering ions.
06:55 Sujit Ghosh: Main problem is that when you install this material in the sea, the actual hurdles will come because see, other than these chemicals, there are a lot of all these microbes in water, it will kind of cover this with biological species. But main problem is that when you go to the real field, if you want to use this material in the sea, two ways it is possible. So, one way is we can put the material in fiber and with a long thread we can dip it in the sea for a few months and then uranium will get collected. Then we can extract after few months and the uranium can be collected again and again. Okay, that means we can reuse it. Another way we can do it is near the sea, we can pump a lot of water and pass through this material and it can capture uranium from seawater. I'm very hopeful that this technology will work one day in real application. Then we can solve the problem of power by generating unlimited power using uranium as a nuclear fuel from seawater.
08:08 Subhra Priyadarshini: Also there is oceanography, nuclear chemistry, this hydrology, chemical engineering and maybe more all working in close coordination.
08:19 Sujit Ghosh: These are our students from here, and one collaborator, who did the theoretical calculation from outside but what we need actual help is for the engineering part -- how to handle this large volume of water.
08:32 Subhra Priyadarshini: Can this material have any other application say to purify sources of water?
08:39 Sujit Ghosh: So particularly in India, we saw that groundwater contains lot of uranium, much more than permissible level. So this is again a problem – this is not good for health, this is a pollutant and hazardous material, although mild, it is a radioactive material. So this material (MOF) will be useful also to capture uranium from groundwater. So it can also solve the problem of clean drinking water, you can say. I'm working from different fields, particularly, let's say radioactive contaminants also, radioactive pollutants, basically, we can say like selenium, mercury and cyanide.
09:28 Subhra Priyadarshini: Right. So your students have been an integral part of your research work. For the young scientists, especially chemistry students listening to you right now, what's that one piece of advice you'd give on how to choose their research paths?
09:43 Sujit Ghosh: So I'd like to say that it is important for students to exposed early to research so that they know exactly, or at least get an idea, of what is the importance of which research. And they can then guess. It is important to try to enter a research lab as early as possible just to get exposed, so that when you do your PhD you know exactly what kind of research to do, what is your actual interest.
10:08 Subhra Priyadarshini: And with rising global energy demands and environmental concerns associated with fossil fuels, research in sustainable energy supply does seem like the research of the future where young minds can be invested. Sujit and his team’s uranium recovery from natural seawater is at the cutting edge. If scaled up, this could offer a potential for nuclear energy supplies that can last centuries. So chemistry coming in to solve the world's energy crisis – that is interesting.
If you liked what you heard, be sure to share this episode with friends and colleagues and check out our archives for more in both English and Hindi. This is Subhra Priyadarshini signing off. I'll be back soon with another very interesting science workplace story. Keep listening to the Nature India podcast.
11:24 Sponsor announcement: This episode was produced with support from DBT Wellcome Trust India Alliance.
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