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Fukushima and the smell of iodine

Dear Reader,

Recently one person claimed to have smelled the iodine from the Fukushima accident in the first few weeks, I wanted to consider if this was possible.

Sheng Xu et. al. Environmental Science and Technology, 2014, 49, 1017-1024 states that the atom ratio of I-129 to I-131 is 16:1. We can calculate the I-131 activity per gram of iodine if we make the assumptions that all of the I-127 and I-129 formed as fission products is stable in the reactor.

The fission yeild of I-127 is 1.24657 x 10-3 for U-235 with thermal neutrons, the fission yeild of I-129 is 7.17849 x 10-3 so the I-127 to I-129 ratio will be 0.17 to 1.00. So the iodine chemical concentration from fukushima will be largely dictated by the I-129.

As iodine can be smelled when the concentration is greater than 1 ppm. This is about 10 mg per cubic meter, this is expressed for elemental iodine (natural iodine), which is 7,874 x 10-5 moles per cubic meter. So we should expect 4.92 micromoles of I-131 atoms per cubic meter.

This is 2.96 x 1018 atoms of I-131 per cubic meter.

As

A = Nλ

And λ = ln(2) / t½ = ln(2) / 691200 seconds = 1 x 10-6 s-1

So the activity will be about 3 TBq per cubic meter. Or 3 GBq per litre. If a typical man at rest inhales 0.5 cubic meters per hour (8.33 litres per minute) then he will get a large dose of radioactive iodine. It is worse if you use the assumption made by divers that a typical diver needs about a cubic foot of air per minute.

Lets assume that a human retains 50 % of the iodine which they inhale and then exhale the other half without absorbing it. Then in one minute our 8.33 litre per minute man will absorb a dose of 12.5 GBq of I-131.

The atom ratio was for the iodine on the day of the earthquake, if we assume that the person was exposed to two week old iodine then at the threshold of being able to smell it they would then get a dose of 3.125 GBq of I-131. I think it is safe to assume that very quickly they will get a very large dose in the range of 100s of GBq (within an hour).

I have never worked out how many GBq of I-131 would be required to kill a typical human (I will not publish an estimate for public safety reasons) but the I-131 dose is greater than the amount I would expect to kill off the thyroid. From what I know about chemistry and biology I think it is safe to say that this intake of radioactive iodine will require specialist treatment for the person to stay alive for weeks, months and years. This is because this dose will at the least cause thyroid gland failure.

As large numbers of people with total thyroid failure have not appeared I think it is safe to say that this extreme iodine exposure of the public did not occur either in Japan or the USA. I would ignore the population who have been diagnosed or treated for thyroid failure by alternative medicine for several reasons. My main reason is that I do not think that alternative medicine would be able to cope with keeping a person with no thyroid alive.

I thus hold the view that anyone who claimed to have smelled the iodine from Fukushima is mistaken.

Paracetamol in Sweden

Dear Reader,

It has come to my attention that the Swedish state want to restrict the sale of one of the most common forms of paracetamol to pharmacy shops. While I can see a case for limiting the size of paracetamol packs which can be sold without consulting a pharmacist I can not see a case for withdrawing the product from supermarkets. I would like to point out that I bought a pack of paracetamol for my wife less than one hour ago, the product was on an open shelf were someone could gain access to it without a pharmacist or other member of staff’s knowledge.

If the supermarkets are not to be trusted with this drug, then I have to say that the pharmacy shop needs to put it behind the counter out of reach of the public. The argument for controlling the public’s access to the drug is a public safety one, so I reason then that just because the shop selling it is a pharmacy shop it will not protect the general public from harm.

I reason that a self destructive person would be able to purchase plenty of paracetamol in a city such as Göteborg by going from one pharmacy to the next and buying only a small amount in each one. But there is an alternative solution, an overdose of paracetamol is dangerous because it causes liver damage. The classic treatment for an overdose of paracetamol is a dose of either of one of two amino acids. One of which is methionine which is used as a food additive for cats and dogs, to keep kitty and rover healthy many food makers add some of the amino acid to the food which is sold for pets. It has already been suggested in the UK that adding some of this amino acids to every paracetamol pill would greatly limit the number of paracetamol related deaths each year. The pros and cons of the addition of this amino acid to paracetamol pills has been the subject of some debate, I would be interested to know if the Swedish state (Läkemedelsverket) have considered the methionine option.

One method of dealing with the problem of long term methionine exposure in people who need to take paracetamol on a regular basis would be to issue only these people with the current methionine free paracetamol. Also the methionine containing pills could be used in some high risk populations such as prisons where the incidence of overdose is higher.

Radioactive drone delivery

Dear Reader,

It has come to my attention that someone has been flying a drone in Japan with a radioactive sample on it, the fact that it contains both Cs-134 and Cs-137 suggests to me that it might be something from the Fukushima area. Cs-137 is a sure sign of radioactivity being formed from nuclear fission, while the Cs-134 is an isotope which is strongly associated with nuclear reactors. It is not formed by atom bomb detonations. The activity is likely to be low, the news story lacks a few things.

1. The dose rate of 1 microSv hr-1, at what distance was that measured at ?

2. How much activity was in the sample ?

My first guess was that someone has collected some radioactive muck from the environment near to Fukushima, and they are trying to scare people with it. The one microSv per hour is a very small dose rate, it is about the same as the background in many places in Europe (such as Göteborg, Sweden). A later news article suggests that the person who did it has been arrested by the police and that he did it to protest about the energy policy of Japan.

I would also like to point out that did the 1 microSv per hour include the background where the measurement was made ? This is an important question.

I would also like to suggest that if people want to protest against an energy policy (or another thing which takes their fancy) that they do not use radioactivity or objects which appear to be radioactive to scare or intimidate people. I have no idea what the state will do with Yasuo Yamamoto, but I would like him to grow up and have some more respect for radioactivity.

I know that radioactivity is not quite to everyone’s liking, I would be an idiot if I claimed that everyone loves radioactivity, but regardless of how radiophilic (radiation loving) or radiation averse you are it is wrong to contaminate or threaten to contaminate as part of a protest or as a means of disrupting the lives of others. I hold the view that delivering a “radioactive” sample on a drone in an attempt to get a religious, political, or ideological goal is in the same class of behaviour as sending a letter spiked with fake anthrax. Both acts are serious crimes and should earn the offender a trip to jail.

Zeolite and related solids

Dear Reader,

Ages ago I wrote a lot about Prussian blue which is a miracle substance, now I am going to write about something which is related to that cesium catching blue solid. It is the main group version made with aluminum and silicon, the zeolites. These are a collection of microporous solids which have anionic frameworks made of aluminum, silicon and oxygen, the ultimate non-zeolite zeolite is porous silica such as a MCM48. Here we have a porous solid which has the empirical formula of SiO2. Such a solid made from Si(IV) centers and oxygen(-II) ions (oxide anions) is electrically neutral, as a result the silicas are not normally ion exchange materials. Equally if a pure alumina is made it has an empirical formula of Al2O3, as it is made of Al(III) ions and oxide anions then again it forms a neutral lattice which does not make a good ion exchanger. However if a silica has some of the silicons replaced with aluminum to form a aluminosilicate then a lattice can be formed in which the solid retains the “silica’s metal to oxygen ratio” which now having an excess of oxygen anions. This charge imbalance is normally resolved by including cations which are not part of the covalently bonded lattice. In some cases these cations are fixed deeply within the lattice in places where they cannot escape from while in other cases such as the microporous zeolites these charge balancing cations are in sites which are accessible to the solvent. In some cases the charge inbalanace is so great that some of the oxides are converted into hydroxides or are replaced with fluoride anions to form solids such as the mica mineral biotite.

Biotite is a mineral which I have been using in a project funded by SSM on the effects of surgar acids on the absorption of radionuclides onto mineral surfaces. I will save these results for another day. Now before we get onto the zeolite lets look at the biotite, it has the following data for the cell a = 5.343 Å, b = 9.258 Å, c = 10.227 Å Z = 2; beta = 100.26° V = 497.79 Den(Calc)= 2.89

The solid has the empirical formula KMg2.5Fe2+0.5AlSi3O10(OH)1.75F0.25 If we were to replace all the aluminium with silicon (getting rid of the K atom) and all the hydroxides with fluorides we would get a formula of Mg3Si4O10F2

This would be 3 x Mg and 4 x Si (+22 charge in total) and ten oxides and finally two flourides (-22 in total). In terms of charge balance the solid would be the same as Si11O11 but it might not be possible to get the right layered strucutre without the magnesium atoms. Here is a picture of a unit cell of biotite, the orange atoms are oxygens, the pale blue are magnesiums, the pink ones are silicon and the purple ones are potassium atoms.

A unit cell of biotite

A unit cell of biotite

The centre of the layer contains a mixture of iron, magnesium and titanium atoms, while the outer part of the layer contains silicon and aluminum atoms. Here is a picture of the cell where only oxygen, silicons and potassium atoms are shown.

Biotite cell with only potassium, oxygen and silicon atoms shown

Biotite cell with only potassium, oxygen and silicon atoms shown

Now if we show a spacefilling diagram of several layers of biotite, it should be clear that the solid has layers of potassium atoms which allow the solid to bind metals by ion exchange.

 

The layers of biotite showing the potassium in purple, oxygen in red, silicon/aluminium in gold and magnesium sites in blue

The layers of biotite showing the potassium in purple, oxygen in red, silicon/aluminium in gold and magnesium sites in blue

We will get back onto biotite and other zeolites soon.

Tin oxide based ion exchange solids

Dear Reader,

I was reading the other day about ion exchange solids which are based on metal oxides such as tin and titanium dioxide. The surface of these metal oxides can absorb cations, this is a bit different to the organic resins such as DOWEX 50 which is a polystyrene with sulfonic acid groups.

One likely way in which the metal oxides such as tin oxide can bind to the metals is at the surface, when the crystal is cut then the surface will have some dangling bonds. I suspect that the oxygens which do not coordinate to the same number of metal atoms as those oxygens which are fully within the solid will bind to protons thus forming hydroxide groups on the surface.

If we look at tin dioxide we will see that a oxygen is shared between three tins while each tin binds to six oxygen atoms. If we were to cut the crystal in the right way we could expose the oxygen atoms, these oxygen atoms can then bind to protons to thus form hydroxyl groups like those on some silicas.

In common with silica it is possible to add organic groups onto a tin oxide by simple treatment with a trialkoxy silane such as 3-aminopropyl triethoxysilane[1] or 3-methacryloxypropyl trimethoxysilane.[2] Now lets get back to the structure of tin dioxide.

It has a tetragonal cell which is a 4.7402 by 4.7402 by 3.1856 Å box, the fractional coordinates of the atoms are as follows.

Element x y z
Sn 0 0 0
Sn 0.5 0.5 0.5
O 0.3073 0.3073 0
O 0.6927 0.6927 0
O 0.8073 0.1927 0.5
O 0.1927 0.8073 0.5

We will discuss tin oxide in further detail soon

 

[1] C.J. Liu, K. Oshima, M. Shimomura and S. Miyauchi, Journal of Applied Polymer Science, 2006, 100, 1881-1888.

[2] W. Posthumus, J. Laven, G. de With, R. van der Linde, Journal of Colloid and Interface Science, 2006, 304, 394-401.

 

 

Zirconium phosphates

Dear Reader,

A while ago I wrote a lot about Prussian blue the wonder solid which captures cesium, the fact that people want to read what I write about Prussian blue made me think about the other inorganic ion exchange solids. One important one is the 2D network of zirconium hydrogen phosphate.

This can be quite simple to make, one synthesis is simply boiling together a zirconyl salt with phosphoric acid. This forms a layered solid which contains hydrogen phosphate groups, the hydrogen phosphate groups can be deprotonated and then cations can bind to the solid. One important person in this field is Abraham Clearfield who has written many papers on the subject of this class of solid. (Brian M. Mosby, Agustín Díaz and Abraham Clearfield, Dalton Trans., 2014, 43, 10328-10339).

Here we can see one of the layers in the solid it is a 2D network of zirconium atoms and hydrogen phosphate groups.

A layer of zirconium hydrogen phosphate

A layer of zirconium hydrogen phosphate

The 2D sheets then make a layered solid with many many layers. Here are some pictures of the layers of the solid.

Three layers of the layered zirconium hydrogen phosphate

Three layers of the layered zirconium hydrogen phosphate

When the zirconium phosphate is immersed in a solution of a metal some of the protons in the hydrogen phosphate groups can be replaced with metal ions, for example in the following diagram the layers in a potassium exchanged zirconium hydrogen phosphate can be seen.

One layer of the zirconium phsophate after exchanging with potassium ions

One layer of the zirconium phosphate after exchanging with potassium ions

Again the layers can be seen

Three layers of the potassium exchanged zirconium phosphate

Three layers of the potassium exchanged zirconium phosphate

We will have a look at some other interesting solids soon,

All vs Some

Dear Reader,

Sadly one of the classic errors in thinking has shown its ugly face again, this is the issue of “all vs some”. This can be understood as a person thinking that because one example of a person, thing or idea from a class has one set of properties then all things from that class, set or group must share this property.

For example I know a Romanian woman who is a chemist who likes motorcycles and is training for her motorcycle license. Now I sincerely hope that none of readers would be so silly that they then think that all women from Romania are trained in chemistry and have a liking for motorcycles. But sadly when it comes to chemical substances a pandemic of this stupidity exists.

One area within chemistry where this occurs is “ionic liquids”, my own view of ionic liquids is that they are a very wide class of substances I was reading the news at chemistry world in which a comment “Ionic liquids have previously generated much excitement, but also some fierce criticism owing to some being toxic” was made. I would like to point out that this is a good example of “all vs some”. I will admit that some ionic liquids are perfectly horrible but the horrible nature of one ionic liquid does not change how nice/horrible the next one which you encounter is. One of the best books about how to think (straight and crooked thinking) in chapter two considers this problem of “all vs some”.

Plenty of ionic liquids exist which are made of food grade chemicals which are close to harmless, for example choline salts are used as vital nutrients in some animal feed. From choline salts it is possible to form ionic liquids with anions like lactate (carboxylic acid found in milk) can be made. Such an ionic liquid will not be toxic, it is possible to use it as food for growing microbes.

I think that we need to be careful of the “all vs some” problem, you will also get a reverse problem where a person attracted by the good features of one example of a set then assumes that all other examples of that class are equally good. While if you get lucky and find something which makes you happy or satisfies some other need it is reasonable to continue to search within that class for another example of that class which is equally good or even better. It is impossible to give any warranty that it will be possible to find a better example within the class.

For example carboplatin and cisplatin are drugs which can cure cancer, they contain platinum but it is unreasonable to then assume that all platinum compounds can cure cancer. Also despite the fact that a lot of platinum compounds have been screened as anticancer drugs, very few were found to be suitable for the treatment of cancer. The fact that cisplatin / carboplatin were so good does not make it a certinity that a new effective cancer treatment system based on platinum chemistry will be possible.

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