March 17, 2018

Forensic Analysis of One of the Earliest Weapons Grade Plutonium Samples Ever Prepared.

Recently I've been studying - because some excellent articles on the topic have been showing up in the scientific journals I routinely scan and or read - the interesting chemistry of the clean up of one of the most radioactively contaminated sites in the world, the Hanford Reservation near Richland, Washington.

Here for instance, is one such paper on this topic, on which I may comment in the future in this space: Review of the Scientific Understanding of Radioactive Waste at the U.S. DOE Hanford Site (Peterson et al, Environ. Sci. Technol., 2018, 52 (2), pp 381–396)

I am always interested in radiochemistry, since I believe understanding it represents the last best hope of the human race.

Coincidentally, I've been going through old papers that I collected years ago but never read to sort them into appropriate directories, and I came across an interesting paper relating to one of the earliest known samples of plutonium ever prepared, prepared in the early days of the Manhattan project. The paper is here: Nuclear Archeology in a Bottle: Evidence of Pre-Trinity U.S. Weapons Activities from a Waste Burial Site (Schwantes et al., Anal. Chem., 2009, 81 (4), pp 1297–1306)

The Hanford site, which is where most of the plutonium for America's nuclear weapons was made, for most of its history as a production plant, operated on what its operators considered to be "emergency" conditions, extreme conditions of races against real and putative enemies, in both hot and cold war. The mentality was not focused at all on the long term other than potential post apocalyptic scenarios in which our enemies nuked us before we could nuke them. In such a mentality, so far as radioactive fission products as well as toxic chemicals were concerned, they were handled in a way that in our more distant time we would regard as extremely cavalier. In the earliest years, nuclear by products, often referred to as "nuclear waste," were often disposed of in open trenches, to be replaced later by single shell tanks, some of which famously leaked, and then in double shell tanks. Poor records and inventories were kept, but again, the remediation of this site has some fascinating chemistry and the clean up shows as much ingenuity as the creation of these materials did.

By the way, the existence of the Hanford Site has not lead to a death toll that even remotely approximates the number of people who have been killed by the by products of combustion of dangerous fossil fuels and biomass, which approximates about 7 million people a year, every year, which is roughly the equivalent of nuking and completely wiping out a city the size of Hong Kong every year, without stop. There are people, not very bright people, who wish to represent Hanford as the worst environmental problem that has ever existed, scientifically illiterate journalists for example. The 55,000 citizens of Richland, Washington are leading useful lives - many are scientists at Pacific Northwest National Laboratories - and are not dropping dead in the streets.

But no matter.

Anyway...Nuclear Forensics and the earliest plutonium samples:

From the opening text of the paper:

Here's a photograph of the safe and the bottle in it in which the plutonium was found:



The caption:



Apparently the process utilized to isolate the plutonium used a lanthanum fluoride carrier. It must have been the case that there was very little plutonium available at the time of the isolation, which is not surprising. In 1944, a chemist named Don Mastick broke a test tube in such a way as to end up eating what was then the world supply of the element; and many years later, as an old man was interviewed on the subject before dying in 2007 at the age of 87.

The scheme for analyzing the contents of the bottle is shown in the following graphic, also from the paper:



One of the interesting things about this paper which surprised me - this after more than 3 decades of reading about nuclear science - was that there was enough Na-22, a radioactive isotope of sodium in the sample to use it as a kind of tracer of the history of the bottle. As it is a radioactive isotope that is neutron deficient, as opposed to neutron rich, it's not an isotope I ever bothered thinking much about. It arises from the interaction of fluorine, a monoisotopic element with a mass number of 19, with alpha particles:





You learn something every day. This might be of interest to all those people working on MSRs (Molten Salt Reactors) utilizing the "FLIBE" or "FLINAK" salts. It's probably not a serious drawback, but one probably requiring some attention.

Some additional comment from the authors on the role of Na-22 in their analysis:



Figure 4:



The caption:



Further elaboration is in the text of the original paper about how to use isotopes like 22Na (or similar secondary nuclear reactions) to determine whether the same contains all of the plutonium originally available from its source, or only a fraction of it.

By the way, the plutonium in this sample was almost pure Pu-239, a grade of plutonium that today would be considered an extreme weapons grade material. This is unsurprising, since the Manhattan project had no way of knowing the effect of plutonium-240 would have on their weapons, and probably went to great lengths to avoid its accumulation. This requirement, regrettably greatly increased the volume of waste in order to isolate it, and this remained an issue, even after it was understood that weapons grade plutonium could tolerate more Pu-240 than was realized. Weapons grade plutonium is still not at all like reactor grade plutonium.



The caption:



Using the ratio, the authors determined that the source of the plutonium was not Hanford's more famous B-reactor, but rather the X-reactor, which was not located at Hanford, but rather at Oak Ridge.

This is explicated in the full text.

Interesting stuff, I think.

I wish you a pleasant rest of the weekend.

March 11, 2018

Copernecium forms a mercury like amalgam with gold.

I'm going through old papers I collected 10 years ago but never read, and I came across this oldie but goodie from 2007, which somehow found its way into a directory about the environmental and climate impact of large dams, along with an obituary of John Wheeler:

Chemical characterization of element 112 (R. Eichler, N. V. Aksenov, A. V. Belozerov, G. A. Bozhikov, V. I. Chepigin, S. N. Dmitriev, R. Dressler, H. W. Gäggeler, V. A. Gorshkov, F. Haenssler, M. G. Itkis, A. Laube, V. Ya. Lebedev, O. N. Malyshev, Yu. Ts. Oganessian, O. V. Petrushkin, D. Piguet, P. Rasmussen, S. V. Shishkin, A. V. Shutov, A. I. Svirikhin, E. E. Tereshatov, G. K. Vostokin, M. Wegrzecki & A. V. Yeremin, Nature volume 447, pages 72–75 (03 May 2007))

One of the most dubious mining practices in the world is the extraction of gold from ores using liquid mercury, because mercury readily dissolves gold, which historically was the most problematic element to dissolve, at least until the discovery of a mixture of acids, hydrochloric and nitric acid, known as "aqua regia" because it dissolves "the king of metals." Aqua regia however is somewhat less effective when recovering gold from ores than mercury, and therefore mercury is still utilized for this purpose, particularly in wild cat mining of the type utilized to recover not only gold but many diffuse elements such as tantalum and the lanthanides, leading to distributed pollution that is difficult to address.

To recover gold from solution in liquid mercury, the mercury is distilled off.

Wonderful.

Anyway...

Element 112, now known as the element Copernicium, is a cogener of the toxic metals mercury and cadmium, the toxicity of which is largely an effect related to their displacing another cogener, zinc, in metalloenzymes, thus inactivating them.

The ten year old paper linked above refers to its chemistry, which has been the subject of some interest owing to relativistic corrections to its electronic structure, a topic to which the wonderful host of this group, directed my attention recently. It has not been clear whether or not Copernicium would be an inert gas rather like radon or a liquid. From the text:

Some interesting details about this elegant experiment requiring significant teamwork:



Cool, I think.

The conclusion:



The added bold is mine.


(Cn substituted for 112 and Fl for 114 in the original text where needed to distinguish the mass number from the atomic number, owing to the inability to utilize superscripts here.)

The host here recently directed me to a wonderful paper on the effects of relativity on the chemistry of heavy elements, which by the way, is evoked to account for the fact that mercury is a liquid rather than a solid.

It is here: Relativistic Effects in Chemistry: More Common Than You Thought (Pyykkö, Annual Review of Physical Chemistry, Vol. 63:45-64 (Volume publication date May 2012)

Have a nice Daylight Savings Time Sunday afternoon.

March 7, 2018

Uranium catalyzed electrolysis of water to produce hydrogen.

The paper I will discuss in this post is this one:
Uranium-mediated electrocatalytic dihydrogen production from water (Meyer et al Nature volume 530, pages 317–321 (18 February 2016))

First some bitter background:

I don't have much use for the anti-nuke ersatz "climate activist" Joe Romm, who I consider an appalling fool, but despite my general contempt for almost all of his rhetoric, there is one thing about it with which I agree: Hydrogen will never be a useful consumer fuel, useful for powering cars and other dubious artifacts of our modern "screw the planet and the future be damned" culture.

On this, he disagreed with his pal, fellow anti-nuke Moron Amory Lovins, who once promised us Hydrogen Hypercars in Showrooms by 2005 adding to his long list of stupid Ouija board quality prognostications about energy.

The referenced National Geographic puff piece on Lovins was published on October 16, 2001.

At Mauna Loa the weekly average for concentrations of the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere posted on October 14, 2001 was 368.16 ppm.

On October 15, 2017, the posted figure from the same source was 403.97 ppm.

Nevertheless, irrespective of what a fool Amory Lovins is, hydrogen is, and for as long as an industrial society exists, will always be an important captive intermediate for a variety of products, the most important being ammonia, but for many other products as well, including fuels. Hydrogen can be used to reduce ("hydrogenate" ) carbon dioxide or carbon monoxide to make dirty fuels like gasoline (the Fischer-Tropsch process into which the Carter administration put lots of research effort) or clean fuels like dimethyl ether, and less attractively, methanol. This potential for a closed carbon cycle was enthusiastically advanced by the late great Nobel Laureate George Olah in his widely cited 2011 paper Anthropogenic Chemical Carbon Cycle for a Sustainable Future (Olah et al J. Am. Chem. Soc., 2011, 133 (33), pp 12881–12898)

Olah's dead, and despite his noble efforts during his magnificent life, the planet is still dying.

What Lovins, a poorly educated ignoramus who is nevertheless thought by some, including himself, to be a "real stable genius," was too stupid to understand, or simply deliberately avoided since he makes a lot of money "consulting" for huge and very dirty dangerous fossil fuel companies, is that 99% of the hydrogen on this planet is generated by the energy wasting process of reforming dangerous natural gas, and less commonly these days, coal.

Lovins liked to pretend, or at least convince his acolytes, that hydrogen could be industrially made by what he called "soft" technologies - they are actually environmentally egregious nightmares of unsustainable industrial chemistry - the solar driven electrolysis of water.

This is pretty funny, since Lovins, who made his name hyping "energy conservation," while apparently knowing zero about the laws of thermodynamics, never bothered to account for the fact that electrolysis of water is one of the most thermodynamically inefficient processes known for producing hydrogen. About 1% of the hydrogen on the planet is so produced, and of this 1%, almost all of it is produced as a side product in the production of chlorine gas utilized to make bleach, polyvinyl chloride and historically interesting molecules like DDT and CFC's. Until very recently and for most of the period of Lovins' awful career, the main electrode for undertaking these electrolysis efforts was a mercury electrode. Bleach produced still produced this way - and there is some - usually contains small amounts of mercury, making it the third largest contributor to mercury in the environment after coal burning and medical waste.

(By the way, despite all Lovins’ hype about energy conservation, the strategy has failed as badly as the solar and wind industries have failed. In 1973, world energy demand was estimated to be 256 exajoules. As of 2016, world energy consumption is 576 exajoules.

IEA 2017 World Energy Outlook, Table 2.2 page 79 (MTOE converted to exajoules.)
For the 1973 figure see Current Energy Demand; Ethical Energy Demand; Depleted Uranium and the Centuries to Come and references therein)



All the above said, the production of hydrogen via electrolysis also results in the isolation of heavy water which is useful in the production of stable labeled isotopes useful for chemical, biochemical, medical and environmental research. What should be equally important – or would be in a sane world – deuterium is a key component of a potentially extremely mass efficient type (particularly in thorium based cycles) of nuclear reactor, commonly called a CANDU reactor, a result of having been developed in Canada, but otherwise known more generally as a heavy water reactor. The main national nuclear energy program investing in this approach is India’s, although heavy water reactors do still operate in Canada.

Thus there is a role for electrolysis and for improving its efficiency.

This brings me to the paper cited at the outset of this post. The complexity of the electronic structures of the light actinide uranium and the multiple oxidation states suggests - as do other elements with this property of having multiple oxidation states . (This fact, the complexity of the electronic structure of uranium, was the subject of a recent post of mine in this space, Highly sensitive, uranium based UV detectors.)


As an “actinide,” uranium is expected to exhibit a +3 oxidation state, and it does. However the shielding of the 5f orbitals is less effective than it is for the corresponding lanthanides, where the filling of 4f orbitals results in lanthanide chemistry being being dominated by this +3 oxidation state, so much so, that the separation of the lanthanide elements from one another was long problematic.


Because of this ineffective shielding in uranium however, f orbitals are available for chemistry, and this is why, until the Seaborg actinide concept was developed and accepted, uranium was thought to be a cogener of tungsten, rather than a cogener of neodymium, with which it shares only limited chemistry.


Like uranium hexafluoride, a +6 compound, for example, a gaseous compound at moderate temperatures that plays a huge role in isotope separation both for nuclear power and for nuclear weapons, tungsten hexafluoride is a gas, and both tungsten and uranium form, for another example oxocations.

(However for reasons having more to do with quantum chemical formalism than actual chemistry, uranium is -rightly I think - considered an actinide, as is thorium, which effectively exhibits no f related chemistry at all, and in fact, doesn’t really possess a 3+ oxidation state of any significance.)

The availability of multiple oxidation states can be used to reduce water and this brings me (finally!) to a discussion of the paper cited in the opening paragraph of this post.

From the introductory text:

Here, from the paper, is the structure of the complex:



The caption:



I very much doubt that this complex - and here I'm referring to the organic ligands and not the final synthesis shown in the graphic - is trivial to synthesize, but then again, it's a catalyst not a reagent, and depending on its stability and turn over rate, it might be viable to make it.

The authors propose the following mechanism for the hydrogen reduction reaction:



The caption:



Their experiments to confirm this mechanism sound like incredible fun:



Frozen toluene at 7.5K, I'd guess is made by dipping toluene in liquid helium; that my friends has to be fun.

And then...



Here's the EPR spectrum:



And its caption:



And finally the full cyclic mechanism of the electrolysis, wherein the oxidized uranium is reduced to U(III):



And its caption:



This device is a battery, and like all batteries, it wastes energy, however it wastes less energy than other electrolysis devices.

Regrettably the world has chosen, much to the detriment of the environment to choose to explore so called "renewable energy" to address climate change, surrounding this choice with all kinds of delusional statements designed to obscure the complete and total failure of this choice to address the expanding use of dangerous fossil fuels.

By their very nature, these systems are wasteful, since they necessarily require redundant systems, usually systems involving gas turbines. To the extent that the excess rotational energy of a spinning turbine being shut for a few hours so we can all make excited, if nonsensical, demonstrations of how great solar energy is, can be recovered, a battery is not a bad idea as a brake, as is the case in hybrid cars. At least some of the energy can be recovered and not wasted.

I actually think that this system, the uranium catalyzed electrolysis system might make sense in very limited circumstances, for example in remote systems, such as on space craft powered by RTG's, where the waste heat of the RTG might serve to provide operating temperatures for fuel cells operating on hydrogen.

Large scale energy storage should be a non-starter on environmental grounds but this is not culturally accepted yet, given the general contempt for science and the inexplicable pop enthusiasm for so called "renewable energy."

A better use for depleted uranium in my view, would be to convert it to plutonium and fission it, but that's just my view.

Have a nice evening, and if you're in this Nor'easter, as I am, by all means be safe.

March 4, 2018

Sexual Harassment in Science.

As a culture, it is a good thing from my perspective on which to reflect.

This video on this interesting question is from the American Chemical Society.

Especially for senior people, it's worth reflecting on the type of environment provided in your work place.

https://www.acs.org/content/acs/en/acs-webinars/popular-chemistry/harassment/video.html

March 3, 2018

Understanding the Relationship Between Chemical Feedstocks and Dangerous Fossil Fuels.

Recently in this space, I posted a very esoteric piece - so esoteric that it understandably provoked no comment - on the preparation of p-xylene from dimethylfuran, a chemical that is accessible from biomass such as straw.

The Conversion of Cellulosic Biomass Into Aromatic Compounds.

In so doing, I failed to apply a lesson I often - albeit with very limited success - try to evoke whenever one hears these "feel good/sound good" bits of environmental wishful thinking - which is to think about scale. For instance, the scale of world energy consumption as of 2016 was 576 exajoules per year - fraction of which that is derived from dangerous fossil fuels has been rising not falling throughout the 21st century - and all of the endless hype about the solar industry's "percent" growth is merely an attempt to bury the issue of scale. Wind and solar energy combined, despite all the cheering, did not produce 10 exajoules of energy in 2016 and thus has been insignificant, is insignificant, and always will be insignificant.

A recent publication in one of my favorite journals Environmental Science and Technology has served for my inattention to issues of scale in referencing a lab scale process as significant; there's a long way between "there" - "there" being significance - and "here," "here" being a world in which the collapse of the planetary atmosphere is accelerating and not as popularly imagined, even remotely being addressed. The paper is this one, about the role that dangerous fossil fuels play in the chemical industry, the chemical industry being at the very core of and essential to our way of life, pretty much involved in everything a modern bourgeois person - such as I am - does. Here is the paper: Mapping Global Flows of Chemicals: From Fossil Fuel Feedstocks to Chemical Products (Levi and Cullen, Environ. Sci. Technol., 2018, 52 (4), pp 1725–1734)

This graphic from the paper shows pretty much everything you need to know about it:



(Similar types of flow diagrams for energy are widely available from the Lawrence Livermore Laboratory and other places. I sometimes post a particular version here and there showing the energy flow diagram for Denmark, that offshore oil and gas hellhole showing how trivial its much ballyhooed and hyped wind industry is.)

Anyway.

From this diagram, one can discern the world requirement for "BTX" (Benzene, Toluene and Xylenes) is on the order of 80 million tons, of which roughly 70 million tons is carbon. This compares to the average annual average amount of carbon dioxide that is routinely dumped into the atmosphere while we wait for the grand super duper renewable energy nirvana that never comes, roughly 35 billion tons of CO2, corresponding to about 15 billion tons of carbon.

70 million tons may be accessible via "waste" biomass. Over on another website where I was banned for telling the truth, I roughly calculated from available references that the total carbon content of all the straw in China is roughly 267 million tons.

This of course does not account for transporting and processing all the straw in China, of course, just so I'm not encouraging false optimism.

According to the cited paper, the world chemical industry's contribution to climate change from direct by products of the chemicals themselves as carbon dioxide, is relatively small, 267 million tons, or less than 1%. More serious is the release of methane, and probably less serious, but significant all the same, is the contribution to climate change from nitrous oxide, a side product of the ammonia industry on which our food supply depends:



However this ignores the energy input of chemical processing, which is far more significant.

From the opening text of the paper we have these remarks from the authors:

Returning to the issue of the ammonia industry, it is worth noting that 55 million tons, graphically it seems to be on the order of 1/3 of the total, comes from coal, the most dangerous of the three dangerous fossil fuels. Coal is often reported as being "dead," which is nonsense; reports of its death are greatly exaggerated, to steal a Twainism. Between 2000 and 2016 coal was the fastest growing source of primary energy on this planet, increasing by 2/3 of the amount used in 2000 (roughly 90 exajoules worth) by 60 additional exajoules. The contribution that coal makes to ammonia synthesis may be trivial in comparison to its use in the energy and steel industry, but it is real and significant.

I found this paper thought provoking, and it served for a useful refocusing on the realities of our increasingly dire environmental situation.

If we want to be serious - and there's no way that we are even remotely so in any country or even in any political party in any country - scale is the most important thing of which we can think.

I hope you're having a pleasant weekend.

March 2, 2018

Nature Climate and Atmospheric Science: Dramatic declines in snowpack in the western US

According to this open sourced paper in Nature Climate and Atmospheric Sci, the Western US Mountains Can't Hold Snow; the West Can't Get Water: Dramatic declines in snowpack in the western US (Mote, et al npj Climate and Atmospheric Sciencevolume 1, Article number: 2 (2018)

This is not a short term event. It's a trend.

The article is, again, open sourced and there's not a whole lot of need to go over or quote the rest of it. It's pretty clear.

It seems to be involved with something called "climate change." A lot of whiny people have been carrying on about it, but fortunately we've successfully been able to completely and totally ignore them.

Don't worry; be happy.

California has lots of wind turbines and lots of solar cells and therefore all of our problems will shortly be solved, because they, and the natural gas on which they depend most of the time, are clean and green.

Have a nice Friday.

February 27, 2018

The Conversion of Cellulosic Biomass Into Aromatic Compounds.

Most of the chemicals utilized in the preparation of polymers are currently derived from petroleum, and to the extent they are degraded either by combustion or other means, the represent a climate risk.

Since we have, in our times, spectacularly failed to address climate change, offering in lieu of things that actually work truckloads of wishful thinking (solar and wind) future generations will need to clean up our mess, the biggest mess being the planetary atmosphere and the oceans with which they are in a shifting equilibrium.

Although plastics represent a huge environmental problem, the problem would be mitigated to the extent that they were obtained from air rather than from petroleum, since in the former case, they would represent sequestered carbon.

Some years back, there was a lot of talk about converting cellulosic materials into ethanol via fermentation schemes of various types. All of these efforts have more or less commercially failed, probably because, among other things, they were water and energy intensive.

However, the chemical dehydration of cellulosic materials, generally with acid and heat, is known to produce compounds in a class known as furans, five membered unsaturated rings, generally with one or two single carbon side chains. (Historically almost all the furan in the world was made from oat hulls, until petrochemicals replaced them via a route from butadiene obtained from dangerous fossil fuels.)

Here, for example is the structure of dimethylfuran:



A problem with biomass to chemicals conversion has been, however, the low production of aromatic compounds like benzene, toluene and the xylenes, one of which p-xylene, aka as 1,4-dimethylbenzene is an important precursor to common plastics like PET, polyethylene terephthalate, a polymer used in bottles and in clothing. Xylenes are also important constituents of cleaners, fuels, paints and varnishes, especially those requiring special properties such as in works of art.

It is thus with interest I came across the following paper published by Chinese scientists in the scientific literature: One-Step Conversion of Biomass-Derived Furanics into Aromatics by Brønsted Acid Ionic Liquids at Room Temperature (Zhang et al, ACS Sustainable Chem. Eng., 2018, 6 (2), pp 2541–2551)

The introduction covers what I just said.

The authors express their goal and what they have accomplished a little further on:



Reference 35, on dehydrating and oxidizing glycerol to give acrylic acid is this one from the same journal: Highly Selective Production of Acrylic Acid from Glycerol via Two Steps Using Au/CeO2 Catalysts

The "ionic liquids" are salts, usually with one or two organic species, that are liquid at or near room temperature. Most of those used in the paper are of the alkylimidazole type, albeit mostly with inorganic counterions like sulfates or phosphates.

Some pictures from the paper:



The picture shows a tree as the source, but this is unnecessary, straw and things like corn cobs would work quite as well, if not better. Wood, by the way, is a source of aromatic compounds, from the lignin they contain in addition to cellulose, but in general they are phenolic, having one or more acidic -OH moieties on the aromatic ring.

Here the authors compare their work, (c), with those of previous authors working on the same idea, furans to aromatics:



Here is some graphics showing the yields and selectivity under several conditions:



The caption:



PX is paraxylene, 2,5 DMBA is 2,5 dimethyl benzoic acid.

Reaction parameters:



The caption:



Reaction mechanisms leading to the two main aromatic products:



Note the role of the inorganic anions.

The free energy diagram associated with this mechanism:



The authors thus conclude:



Interesting I think, esoteric but interesting.

Have a pleasant Tuesday tomorrow.

February 25, 2018

Charles Ball describing being taken from his mother forever.

Recently in this space, I was describing the pain of reading the book The Half Has Never Been Told about the relationship between the origins of all American wealth, past and present, and human slavery:

I can only read this book in short spurts until the pain becomes too great. Read it, I must.

The early chapter makes considerable reference to the autobiographical work of the escaped slave Charles Ball, Slavery in the United States: a narrative of the life and adventures of Charles Ball, a black man, who lived forty years in Maryland, South Carolina and Georgia, as a slave,

Yesterday during my library research into other topics connected with my scientific work, I paused to download an electronic version of Ball's book, which begins with a description of being taken from his mother.

I reproduce a portion here:

Unbelievable, absolutely unbelievable...

Lest we forget, this is who we are.

February 24, 2018

Cogenerating Thermochemical Hydrogen While Recovering Waste Copper.

The paper from the primary scientific literature to which I'll refer is this one:

Co-production of Hydrogen and Copper from Copper Waste Using a Thermochemical Cu–Cl Cycle (Farrukh Khalid* , Ibrahim Dincer, and Marc A. Rosen, Energy and Fuels, 2018, 32 (2), pp 2137–2144)

There are many hydrogen cycles known, water splitting thermal cycles. The CuCl2 cycle is just one of them, other examples include the much studied sulfur-iodine cycle and variations, various cerium cycles (which include carbon dioxide splitting options), zinc cycles...etc...etc.

I've dreamt up a few variations on my own, although I have no idea whether they would actually work.

In general, they all feature the possibility of high thermal efficiency, since they are easily coupled to thermal processes for electricity generation, the generation of heat for chemical processing, and the production of pure oxygen that may be utilized for closed combustion systems that will not involve smokestacks and will, to the extent that oxygen is used to combust biomass, allow for the recovery of carbon dioxide from the atmosphere for its removal.

One limitation of these cycles involves materials science, although we have in recent decades developed some spectacularly refractory materials and others are clearly on the horizon.

One of the problems that humanity faces however is the depletion of important elements in the periodic table, including some in the popular, but spectacularly failed, so called "renewable energy" industry, which is in fact, is neither "renewable" nor sustainable for precisely this reason.

When elements are distributed, as in "distributed energy" their recovery involves energy, and the more diffuse they are, the more distributed they are, the more energy is required to reconcentrate them into a recoverable and useful form. This is a consequence of the second law of thermodynamics, which cannot be repealed by the legislature of California (where such repeal is often proposed, albeit usually "by 'such and such' a date, when conveniently, the people voting on the repeal will be either out of office or dead) or by any other legislature or even by any ersatz or real dictator, orange or otherwise.

The dilution of elements or molecules is known as "the entropy of mixing."

An essential element in our modern life is copper, which is ever more critical particularly because of the sloppy ways we use it, in low capacity utilization systems such as wind turbines, which, since they require redundancy as well as the use of large mass collection systems, and when these systems turn into landfill, the recovery of copper in them will require energy.

That's why this paper is of interest.

From the introduction:

I agree with part of the last statement. Nuclear energy is environmentally friendly, but in my oft expressed opinion, so called "renewable energy" is not.

Hydrogen is not an acceptable fuel, but it an extremely useful captive intermediate where it can be utilized to make sustainable fuels - my personal favorite being dimethyl ether, DME - via the hydrogenation of carbon dioxide (or monoxide).

The introduction continues:



Here, from the paper, is a schematic of the particular copper chloride cycle the authors envision. Note that their cycle requires an electrical input, but not all cycles, not even all copper chloride cycles, do:



Their purpose in including electricity is to reduce the temperatures required. With advances in materials science, this may not be necessary.

Their particular cycle relies on the oxidation of chlorine gas at 950K with water (steam) to give HCl gas and oxygen, and the HCl gas is reacted with copper wastes to generate hydrogen and cuprous chloride (copper (I) chloride) and hydrogen at around 770K, a temperature at which the cuprous chloride is a liquid, simplifying mass transfer. This liquid is electrochemically disproportionated into copper metal and cupric chloride (CuCl2 - copper (II) chloride) and the latter is thermochemically decomposed at 883 K to give chlorine gas and copper metal.

Here's a schematic of the electrochemical step:



Here's a photograph of the actual lab scale operating system:



I used to love putting stuff together that looked like that when I was in the lab. It makes one feel all "sciency." (Sometimes modern instrumentation can look too clean to be fun.)

There's a nice discussion of the thermodynamics in the paper, as well as a simple graphic that shows the story:



The caption:



A number of other graphics in the paper discuss optimization of the temperatures for each step. The interested reader may refer to the original either by subscription or by traveling to a good scientific library.

Note that the electrochemical portion may not be strictly necessary, depending on process parameters, and indeed on chemistry. A well known variant of copper based thermochemical cycles is the copper bromide cycle, and indeed iodide cycles also are possible.

Usually at this point someone will mention cost, usually in the context of declaring that "nuclear energy is too expensive" among other distorted views by which anti-nukes morph into Ayn Rand type Laissez Faire capitalists, usually with a healthy dollop of selective attention.

So called "renewable energy" is not cheap unless it is isolated from the environmentally questionable necessity for redundant back up whenever the sun isn't shining - sunlight is widely reported to disappear for various amounts of time depending on latitude and season - and the wind isn't blowing.

The reality is that the back up - despite all the horseshit about Elon Musk's (and other) unsustainable batteries - is dangerous natural gas, also reported as being "cheap."

It's "cheap" only if someone other than the user pays for cleaning up the trash it leaves behind, for example, carbon dioxide, radioactive flowback water, permanently leaching spent fields, etc.

The people consigned to pay for these clean ups are not the users; it is rather all future generations, our children, our grandchildren, their children, their great grandchildren etc.

The fact is that the dangerous fossil fuel industry is simply allowed to dump its waste directly into the planetary atmosphere without restriction, and without cost, while cleaner forms of energy, notably nuclear energy, are required to show that they can contain all by products indefinitely, over as long a period as stupid people can imagine, even though nuclear materials have a spectacular record of not killing many people, while fossil fuel waste kills millions upon millions of people year after year after year after year with little comment.

Because of this situation, so called "natural gas" is described as being "cheap" even though it is no such thing.

In recent weeks I've been reading about the history of human slavery in this country; a horrible story that is very difficult to read. Sometimes I have to put the books I'm reading down weeping; they're too painful to read but innocent people were required to live these events.

It is hard not to express profound disgust at the generations of white Americans of those times in which human slavery was legal in this country, and the twisted mentality that sought to perpetuate this great crime for many unimaginably cruel generations.

And then I think about how future generations might regard our generation, and I'm not comforted by the thought.

Since all current schemes to stop dumping the dangerous fossil fuel waste carbon dioxide into our favorite waste dump, the planetary atmosphere, have all failed, future generations will be required to clean up our garbage, this while having fewer resources than our generation enjoyed - and squandered - with complete disregard for them.

To get resources, they'll have to dig through our garbage, and probably face huge health risks in doing so. It's hard to think they'll think kindly on us any more than I think kindly on the purveyors of human slavery in the United States.

Maybe processes described in this paper might help a little, but irrespective of leaving them with the paltry record of such unscaled experiments they will be totally in their rights, in my view, to view us with as much or more disgust as I - more than a century later - view the slaveholders and their enablers, North, South, and everywhere else.

Have a pleasant Sunday tomorrow.

February 24, 2018

Highly sensitive, uranium based UV detectors.

I am fascinated by the remarkable chemistry of the actinide elements because of the interesting chemistry of the 5f orbitals.

(One of the "actinides," thorium, strictly has limited or no 5f chemistry, although its considered an actinide nonetheless, for convenience.)

One of the interesting things about the actinides, all of which are radioactive, is that they are excellent shielding materials for high energy radiation, owing to the fact that they have so many electrons - uranium, for example has 92 - making it possible for them to have many electronic transitions, and because they are massive, their inner electrons can absorb very high energy radiation to emit "Auger electrons."

Thus I was fascinated by a paper published recently in the wonderful - if overly dense - journal ACS Appl. Mater. Interfaces, specifically, this one: Highly Sensitive Detection of UV Radiation Using a Uranium Coordination Polymer, published by scientists at the Key State Laboratory of Radiation Medicine and Protection and the School for Radiological and Interdisciplinary Sciences and a few other institutions in Sozhou, China. (Wang et al, ACS Appl. Mater. Interfaces, 2018, 10 (5), pp 4844–4850)

(The Chinese government doesn't hate science quite as much as our government hates it, which is why they are going to eat us alive in the 21st century.)

Here's the introductory text from the paper:

The authors propose a uranium based detector for the following reasons:



LUMO here refers to the "lowest unoccupied molecular orbital" and HOMO to the "lowest occupied molecular orbital." Transitions between molecular orbitals (or in some cases atomic orbitals), defined by quantum mechanics, determine the properties of radiation absorption and emission, not only at high energy levels such as those observed for UV, X-rays, and gamma radiation, but also in the visible range: Color is a function of these effects.

The authors synthesize a "MOF" - a "metal organic framework" - a class of materials that has been the subject of vast amounts of research in recent years. This particular framework is built from uranium atoms, nitroisophtalic acid and dimethylformamide.

Here's a graphic describing the structure of this framework:



The caption:



Although the molecules luminescence nicely, after long term irradiation, the intensity of the luminescence fades:



The caption:



Surprisingly however, this effect seems not to relate to structural degradation of the molecular organic framework, which demonstrates remarkable structural integrity even upon irradiation with higher energy wavelengths, to wit, x-rays and gamma rays, as is shown in the XRD (X-ray diffraction pattern) graphics shown:



The caption:



The EPR (Electron Paramagnetic Resonance) spectra clearly shows the persistence of free radicals, thought to reside on the dimethylformamide ligand:



The caption:



I love this last graphic, because one doesn't get to look at electron density diagrams of molecular orbitals resulting from the mixing of f orbitals all that much:



The caption:



The authors thus conclude:



It's a fine paper, but I will note that my preferred use for depleted uranium is as a precursor to plutonium as a nuclear fuel.

The interesting thing for me about this paper is the stability of this framework in a high radiation field. This suggests it's use as a "breathable" nuclear fuel, albeit one that would operate in a thermal spectrum, thus of use in thorium derived U-233 systems as opposed to plutonium breeding systems.

An interesting paper I think.

Have a nice weekend.