 Hello everyone. So, so far we have been discussing the fundamentals of nuclear chemistry, the all-day related topics related to radioactivity, nuclear structure, nuclear models, nuclear reaction, detection and measurement of different types of radiations and also producing different isotopes. Now, the remaining part of this course, the remaining five lectures or 10 modules of my portion, I will be focusing on the applications of what about knowledge we have gained in different branches of science, of course in chemistry as well as other areas. So, before that I would just like to discuss the basic practices in a radiochemical experiment. So, we do radiochemical separations, we do radiochemical analysis, what are the practices that we need to follow that we will try to discuss in this particular lecture. Okay. So, one of the important radiochemical practices is to do separation. Separation of radioactive isotopes will call as radiochemical separations. Now, we can have different radioestopes or even in the case of actinides, the entire, all the isotopes are radioactive. So, we can also call them as radioactive elements. So, we will be separating actinides or we will be separating other elements, but using their radio traces. Now, one of the important advantage of radiochemical separation, we say this is the other methods of physical methods, like in physical methods, we can be using detectors, I explained the other day delta ee telescopes, where you mean you can separate proton, neutron, alpha particles and so on. The moment you go to heavier elements, there is an overlapping of the signal due to different elements, z and a. And so, in physical experiments you will find it is difficult to resolve the different z and a of the products that are formed in a nuclear reaction or even fission. In radiochemical separation, since we are separating the elements radiochemically and then identifying the mass number by following their particular characteristics, like half life or gamma energy. So, the resolution means in terms of neighboring elements is unique. We can unambiguously assign the z and a atomic number and mass number the particular radioisotope produced in a nuclear reaction. That is what I mean by unique resolution in z and a. Now, what is the need for this radiochemical surprise? Where do we come across? So, that is what let me just give you the brief introduction. Need for radiochemical surprise. So, one is to have the requirement of pure radiochemicals. We will as we go along we will see that there are many areas like particularly you know when you want to use a radioisotope in medicine, particularly in diagnosis. You require a pure radiochemical, a particular tracer, a particular technique of 99m bound to a organic molecule and that formulation should not contain any other chemical form. So, that is what we mean by pure radiochemicals for applications. Sometimes even in the research you are emphasizing some particular compound, a labeled compound and you like to have this as pure as possible. Then we use radio tracers in many, many areas like industry, healthcare, agriculture, environmental research and so on. And the requirement of course in most of the cases will be we require the radiochemically pure and also this is called radio nucleotidically pure means only that isotopes will be present, other isotopes should not be present. They may interfere in the experiments. So, to producing this pure radioisotopes and we require radio chemical, radiochemical separations. Then we have the important area of short-lived radioisotopes. Many, many elements if we know the heavy elements, transactinides, whatever the discoveries are happening at the moment in the area of heavy elements, transactinides, half-lives are all in seconds, milliseconds and microseconds. So, you require very nice radiochemical separation, in fact very fast radiochemical separations so that you can identify the Z8A of these isotopes. So, again that same thing I have mentioned also, chemistry of heavy elements. You are studying the chemistry of heavy elements from the time of nuclear reactions, their production and separation involves very fast radiochemical separations. The short-lived isotopes are also many, many applications in there like for example in PET, positon emission tomography to produce F18 or carbon 11 or oxygen 15, they are very short-lived some of them even seconds. And for the positon emission tomography study that stick applications you require after they are produced, you require them to be sent to the hospital as early as possible. So, they require the fast radiochemical separation. So, radiochemical separations have evolved a long lot over the last many, many years and I will just try to give you a glimpse of that evolution. So, before we go over to the different types of radiochemical separations and the applications, let me try to give you the basic principles. The basic principles that we follow in any radiochemical separation. So, in a way we are doing radiochemistry experiments, we need to take care of certain aspects and certain technologies we use so that you know what is that purpose of that particular. For example, we say carriers. So, in radiochemistry, radiochemical experiments, carrier actually is the stable isotopes of the element of the radioisotope. So, we are using a radioisotope as a tracer for radiochemical separations. So, to want to trace the path of a radioisotope, a radio element or you produce a radioisotope in a chemical reaction maybe fission or a reaction and you have very few atoms of that particular radioisotope. So, if you want to do separation probably you need to carry that few atoms with a bulk material. That bulk material made of the same element but different isotopes stable ones we call as the carrier and this carrier in fact are meant to minimize the loss. If you have let us say 1 million atoms of an isotope like iodine 131 you produce by terrarium. Suppose you have tellurium 130, tellurium 131, tellurium 130, 131 tellurium and this is beta minus 2 131 iodine. I discussed the other day in the radioisotope production. Now this iodine 131 is carrier free that means only 131 iodine isotopes are there. So, if you have a query of 131 iodine you may have about billions or maybe 10 billion. So, 10 for 10, 11 atoms of iodine 130. So, when you do separation in terms of the amount 131 gram will contain Avogadro number. So, 10 for 10 atoms will contain only picogram of quantity. So, you cannot handle such a large small quantity. In fact, when you put them in a container many of them will get absorbed onto the wall of the container. So, minimize the loss due to adsorption or other in the reagents. It is better that you use bulk. So, potassium iodide. So, you use iodide iodine 127 to carry this 131 iodine. So, the losses will be denied. Many a times we require them in a high specific activity. So, you do not add bulk quantity you may add macrogram quantity that power 20 atoms or 20 for 18 atoms like that we try by because of the mass effect. So, you generate large quantity not that large but relatively large to avoid the loss during the chemical surface. Then there is a term called hold back carriers. So, suppose along with the tellurium you have other isotopes for example, in fissure you have 131 iodine you have 132 tellurium they are fission products. Now, both of them are carrier free means only atoms of these reductive isotopes are present and we want to separate 131 iodine and fission product but we do not want to separate 132 tellurium. So, for iodine we may use Ki as a carrier but to prevent some portion of tellurium going into along with the 131 suppose you do precipitation silver iodide. Then there is a possibility that 132 tellurium may get adsorbed onto the precipitate. So, to prevent that adsorption or you may do sovereign extraction of iodine in the current pleuride to prevent the carry forward of tellurium in that extraction we use some stable tellurium telluric acid it can use. So, that this isotopes of tellurium which are radioactive they also remain in the raffinate. So, that is one way of you know. So, these are old bracket they hold the radio isotope in the place where we do not we do not want them to carry along the separation. And the third type of reagents are called scavengers to precipitate unwanted elements before we separate the desired element. So, we use these scavengers are the reagents to separate to precipitate the elements which are not required to be carried forward along the. Like for example, you want to you want to separate barium as barium sulfate or barium nitrate. But along with barium now many rare earths may also go zirconium may go. So, how to prevent that they also they do not go along with barium you can do a ferric hydroxide precipitation. So, you add ferric nitrate or ferric chloride and ammonia to precipitate all the rare earths and zirconium as hydroxides. And so now whatever is that definite you add barium the reagent sulfate or nitrate and you can separate barium in the this form. So, these are called scavenger they scavenge the undesired elements from supposition along with the desired element. So, these are mostly required for precipitation or slower extraction or even ion exchange separation. Now, one of the important parameters for the radiochemical separation is the half-life. Half-life is very important because sometimes the half-life may be short and your time of separation may be long. So, you may lose the whole radioactive isopropyl. Before it is decaying you have to separate. Radiochemical purity is as I the name itself mentioned that what is the form in which the particular isotope is present in the chemical form that is called the radiochemical. And the purity of the radiochemical. So, there not only the isotope but the chemical form. So, if you are present for you want iodine as iodide you want iodine in presence of as in the form of iodide not as iodate. So, iodine present as I minus is the radiochemical if your form desired and iodate is a different radiochemical form which is undesired. So, you would have to produce iodine 131 as I minus not I O 3 minus in a particular application. When you need I O 3 minus then you require pure I O 3 minus I I minus will be input. Radio nucleic purity as the name suggests one third like multiderm 99 is a radio nucleide and you want to separate this one. But any other radio nucleic any other isotope of even multiderm is will be taken as a impurity like multiderm 93, multiderm 101. So, they are present of them in the multiderm 99 fraction will call that a nucleic impurity. So, when you say radio nucleic purity in the fraction of only multiderm 99 in the total multiderm present in that particular consignment. Also this specific activity is a important parameter you require high specific activities in some applications that you define in terms of activity per unit mass, bacterial per gram or curie per gram. So, you depending upon the application you may have to go for high specific activity or you may not be required at times and lastly the radiochemical yield. Many a times you are doing radiochemical separation what fraction of that isotope has got separated in your final fraction. So, you started with that say 10 curie of that particular activity and at the end you get 9 curie of present in that form. So, you can say radiochemical yield is 90 percent. So, this is required to be known and for that sometimes radiotesers are also used. In radiochemical separations, radiotesers help in finding out the radiochemical yield. So, you can add a radio isotope which is not present in your sample and finally you see what percentage of this activity has been separated that will give you the yield of radiochemical separation. So, radiochemical separations in their care there are almost two elements you will find there will be a requirement to do radiochemical separation at some point or other. So, you for example, you are producing iron cobalt you radiate some targets of iron cobalt nickel and produce some isotopes of them and you may suppose you have an alloy and you want to separate a particular isotope you need to do radiochemical separations. You may require to like actinides you want to separate from each other or lathenite you want to springs them. The classic example of radiochemical separation when you have a large number of radioisotope then together is fission products. You radiate uranium neutrons, you get hundreds of fission products in half life ranging from seconds to years. So, you have the fission product starting from let us say selenium yield of selenium may be 0.01 percent or so then the yield is going up it reaching maximum around molybdenum and then it is again goes minimum around caramium tin, caramium medium tin 0.01 percent goes up it becomes maximum around cesium barium and then finally goes down again with the tyrants. So, this all these fission products you know and now of course we have the high resolution gamma spectrum it is set up. So, you can directly see the gamma rays of the fission products say large number of fission products you can see together in the gamma spectrum. But earlier when we did not have the high resolution gamma spectrum we used to do the chemistry of each element. So, much so that we remember the chemistry of each element that how to separate for example, you do you do iodine immediately do solvent extraction right. So, convert to iodine to separation you require antimony make the hydride distillate you require ruthenium make a titanium tetra oxide distillate. So, depending upon the chemical property of that element you can find out a chemical separation procedures. Rare earths they form very stable fluorides fluoride followed by hydrocytes two three cycles and you get pure or rare earths in one. So, all across the periodic table depending upon your requirement you will find you will have chemical separations required for these elements. The heavy elements transectinides you see here from here 100, 356 most of them the chemistry is not known and their chemistry with regard to their lighter homologs are studied how they compare like rutherfordium and hafnium. So, you can you can use the lighter homologs as research to study the chemistry of heavy elements. So, let us discuss some of the radical chemical separation procedures for example, you use precipitation precipitation also can be done in different ways one is the direct precipitation you can take an example I was discussing rare earths you want to separate all of them are prevalent except cerium which can be presented as cerium 4 all others are prevalent and so this trivalent rare earths can be separated by a cycle of hydrocyte or by fluoride. So, fluoride precipitates of rare earths are clear so they are very fine low volume only zirconium may interfere and so you can you can do steps of fluoride and hydrocyte precipitation zirconium will be there all around. So, you can do gamma spectrometry you can separate or you have to go for some complexing agents they are called again they can complex one metal ion keep it in the solution pump while others remain in precipitate. So, rare earths can be separated as fluorides. Stonson barium separations are very because Stonson is pure beta emitter Stonson 90 and barium so if you want to separate them you first dissolve then you first make precipitate as nitrates then you do hydrocyte scavenging to precipitate out the rare earths zirconium other things and then you separate barium and Stonsium barium goes as barium chromate and Stonson will not precipitate in Stonson chromate. Similarly, silver can be precipitated silver iodide famous your silver chloride silver iodide. So, there are many more examples I am just taking some of them other than this direct precipitation there are cases like you can adjust the oxidation state of two elements and separate them for example, cerium and zirconium both are turbulent and they precipitate as iodate if you want to separate cerium from zirconium cerium can be reduced to cirrus by a suitable reducing agent and then you can separate zirconium as zirconium remains as iodate cerium comes in the solution. So, by playing with oxidation state you can do chemical separation one of the very innovative idea is to do isotopic exchange with a preformed precipitate. So, you do not have to add the precipitating agent afterwards and this is required when you have there very short-lived example for 138 cesium very short-lived half-life. So, 138 cesium you want to separate you do not have much time maybe within five minutes you have to separate. So, you what you do not even five minutes actually one or two minutes. So, you can precipitate you can prepare a precipitate or cesium with silico tungstic acid stable element precipitate and you that solution containing cesium like piston product solution you just add shake it for a few seconds and precipitate. So, what will happen there is a stable cesium in the precipitate of cesium silico tungstate 138 cesium will exchange isotopically this one in a few seconds you will find most of the cesium 138 has been precipitated with the cesium silico. So, you can just filter this precipitate and you get most of the cesium 138 in the precipitate. So, that is called isotopic exchange with the preformed precipitate. Similarly, for technician is for the technician you know technician does not have any stable element stable isotope but perchlorate perchlorate iron and TCO4 iron are quite close in similarity in chemistry. So, if you have perchlorate precipitate of tetra phenyl arsonium. So, this is the precipitate. So, instead of technician we use perchloric acid and precipitate this out and again this precipitate you exchange with technician. So, technician of 99 it can be precipitate as a tetra phenyl arsonium perchloric. So, this is like a co-precipitation and very fast you can do radicamical separation. Then you have this orbit extraction it is a very common one of you will you will be knowing that a metal ion let us say in aqueous phase and there is a ligand in an organic phase. So, when you mix aqueous and organic phases both liquid phases together and you shake them vigorously because there is a potential for the metal ion to complex with ligand and which remains in the organic phase that metal will go to the aqueous phase in the interface organic phase in the interface complex with ligand and then metallic and complex state soluble in the organic phase. You can extract the metal ion from aqueous to organic and you can then find out what is the what we call as the distribution coefficient of metal ion into organic phase with respect to aqueous phase. The concentration is organic upon concentration in aqueous is called the distribution coefficient and suppose you are separating two metal ions they will have their own d value. So, the ratio of the d value of A and B is called as the separation factor. So, you can find out separation factor for the separation of metal ions in the solvent extraction. Just to give you an example you want to separate iodine present product iodine. Iodine is formed in present in many oxidation states. So, what you do you first bring all the iodine to I minus using thiosulfate as a reducing agent and now you oxidize I minus to I2. So, all the iodine using bromine. So, now all the iodine is now present in the iodine, molecular iodine which can be solvent extracted into the carbon detector. So, this is how you can do you can do separation by solvent extraction. Similarly, uranium plutonium are you can separate them by a reagent called 30 percent tributyl phosphate in an organic solvent like dodecaene or kerosene. Aqueous phase is three volumetric acid and they have very high distribution coefficient the all of them will go in the organic phase. So, there are many reagents that are used for solvent extraction to diethyl exile phosphoric acid tributyl phosphate phenyl trifluorocacetone tri and octyl phosphate oxide diethyl ether methyl isobetyl putone and so there are many many reagents which are commonly used to do solvent extraction of metal ions from aqueous to organic and later on as a function of different acidity you can strip them back in aqueous form. So, the distribution coefficient depend upon the acidity of the aqueous phase and the concentration in the particular ligand in the organic phase. So, you have to play with the acidity to do the separation. Similarly, ion exchange region ion exchangers are very common reagents for separation of different species. So, again it is based on the partitioning of the solute between a stationary phase that is the resin and a mobile phase the mobile phase is the acid or it can be a base or it can be a containing complex image. You can have resins based on cation exchange or anion exchange. So, like for example, you have a polymeric base styrene or diagonal binge on which you have the anchored the groups functional groups like sulfonate and you have the sulfide group and you have the H plus. So, it is a neutral species, but the S plus is exchangeable. So, the metal ion in the mobile phase can exchange with the H plus and the metal ion will be retained in the resin H plus will be released. In the case of anion exchange resin the this is a quaternary ammonium salts containing chloride as a counter ion are exchanging that. So, you can have the anions exchanging with chloride and you have the anion retained in the column chloride being released. So, you can have this ion exchange from different acidic media HCl HNO3 HClO4 H2O4 and so on. But the important thing is that depending upon the ionic potential metal ions are retained by the resin and then you can do separation. Just for example, you want to separate thorium from uranium. So, you can have anionic cell resin dow X1 cross 8 would keep all uranium thorium in 6 to 8 molar HCl where in uranium forms anionic species but thorium does not form anionic species. So, in the anionic cell resin uranium will be held up whereas thorium will not be held up. So, you can just wash the column all thorium comes in the effluent and you can later on elute uranium by using a dilute acid. Similarly, the individual rarels can be separated using a dow X2 cross 4, anionic cell resin you take all of them in point 1 molar HCl. So, dilute acid in the H plus is not competing all the rarels will be held up in the column and now you want to elute them individually. So, there is a beautiful reagent called alpha hydroxy as a butary acid which will complex this different rarels and since the stability constants are different for different rarels you will find use of the rarels ions having different ionic potential. Hence, different stability constant by eluting with this particular reagent individual rarels will come one by one. The one will be the lowest radio ionic radius lutecium will come first and let lengthen them the last. Another just similar to ionic cell resin you have extraction chromatography. So, here the ligand actually is a on the solid surface. So, you have a solid phase stationary phase solid phase some ligand are jobbed onto an inert support that on the column stationary phase and mobile will phase will contain the metal ions in presence of H plus O H minus and so on. So, you have a solution containing metal ion and you have a ligand jobbed onto the solid support. If you pass the solution or metal ion through this column the metal ion will complex with the ligand and get retained by the column and later on you can elute them. Just to give an example of very careful separation of zirconium hypoenium. Zirconium hypoenium are very chemically very similar because of their similar ionic radii and being in the same group you can separate them using extraction chromatography. This is one example that tri caprilile monomethyl ammonium chloride called eliquid 336 is a extractant absorbed onto this solid support and then you first load it from a dilute acid elute hypoenium with 8 molar SCL and zirconium with 2 molar SCL. So, you can see here this has taken from this paper that zirconium and hypoenium are very well separated. This is hypoenium this is zirconium so well separated that peaks due to two metal ions in the ion exchange in this extraction chromatography system. Now lastly let us discuss the fast radiochemical separations. Many a times you require the hoplites are very short seconds many seconds and so on to even you know less than a minute is a very you require very fast chemistry and so there are techniques like gas jet transport system the gas jet transport system what you do you have a beam so you are doing experiment in accelerator the beam is going here you have a target here now target is thin enough when the beam falls on target the products are found in this chamber and the helium gas is passed through this chamber the helium gas will transport all of them reaction products to the fuel hood in your dump. So, we have a pneumatic system and all the reaction products will go in the fuel hood you can collect the gas the products in a solution to the chemistry. So, the transport time for the reaction products from the reactor or accelerator to the fuel hood becomes a few seconds one or two seconds and then the chemistry also you have very fast chemistry apparatus you can do other one is the pneumatic carrier facility the pneumatic carrier means this is the rabbit you have a rabbit capsule this capsule so target is not in the fixed in the beam but you have the target is fixed in the you irradiate the capsule this is containing the target like in the reactor no so this is a this is a reactor and neutrons are everywhere you have a pneumatic tube through which you take the capsule here irradiate for some time and later on carry it to the fuel hood. So, you have to break open the capsule and the target is present in the capsule you can separate the reaction product from the target. So, here you have only the reaction products in gadget transport system you have here you have the target. So, this is a typical pneumatic carrier facility in the Dravar reactor what colleagues have built where you can carry the rabbit in the fuel hood into the chemistry. So, some of the examples of fast chemistry like antimony, tin, tellurium you can form hydrides within a few seconds you can separate them isotope exchange preformed precipitate, sobrixtaction even you can in accelerators you know for proton means you can accelerate you can radiate in the air. Similarly, for heavy elements you can do rapid chemistry automated rapid chemistry apparatus to have a gadget transport system followed by the high performance liquid converter graphy and one of the elements like you know dubinium 105 was separated by this ARCA system using a gadget system and you can do you can switch between different columns to do separation of different elements. So, atom at a time chemistry means at a time only one atom is formed. So, you do thousands of chemistries to do the separation of large number of times and then that is how you study the chemistry of this element. So, thermodynamic quantities of heavy elements are determined by doing chemistry thousand times where you have at a time only one atom. And lastly, you have the pet positron emission tomography you require a short lived proton emitter like poron 18, carbon 11 and so on. So, you can you have to have very fast and very chemical separations because half lives are very short. So, like for example, FAT from H2O you have H2O you irradiate OH2O with the protein beam proton beam and then you separate FAT from this irradiated water water using a particular precursor and the catalyst. So, this is the reaction given to prepare this FAT in FDG. Then you have to have a half chemical separation where within you know few minutes the whole FAT leveled with diplopous molecule is separated from the irradiated target that is H2O 18. So, the whole module whole system is a very compact form and you do you can supply the radio chemically pure hand sterile sample to the hospitals in a very reasonable frame of time maybe few minutes time you can do the separation. So, I will stop here next I will take the radio electrical techniques and their applications. Thank you very much.