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NNadir

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Gender: Male
Current location: New Jersey
Member since: 2002
Number of posts: 25,196

Journal Archives

Susan Collins tweets: she sent a LETTER to the Post Office that she's concerned about their service.

You can't make this stuff up.

Sen. Susan Collins
@SenatorCollins
The USPS continues to be a lifeline amid COVID-19, especially for seniors, veterans, & those in rural areas who rely on mail delivery for essential goods. I sent a letter calling for the USPS to promptly address the delays in mail delivery.

https://collins.senate.gov/newsroom/senator-collins-calls-usps-address-delays-mail-delivery

https://twitter.com/SenatorCollins/status/1294070606544216064

A mathematical model reveals the influence of population heterogeneity on herd immunity to SARS-CoV2

The paper to which I'll refer is this one: A mathematical model reveals the influence of population heterogeneity on herd immunity to SARS-CoV-2 (Tom Britton1,*, View ORCID ProfileFrank Ball2, View ORCID ProfilePieter Trapman1, Science 14 Aug 2020: Vol. 369, Issue 6505, pp. 846-849)

The scientific publishing community has made all SARS-Cov-2 papers open sourced. There is no need for me to excerpt all that much of it, but it does note that something that all of here know, even if the ignorant white supremacist in the White House is as clueless on this subject as he is on all others: In diversity is strength.

The paper, however, does not actually refer to ethnic diversity, but rather to diversity in age and activity levels, as well as the diversity in restrictions utilized. This, of course is good news.

A few brief excerpts:

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally despite the many different preventive measures that have been put in place to reduce transmission. Some countries aimed for suppression by extreme quarantine measures (lockdown) and others aimed for mitigation by slowing the spread using certain preventive measures in combination with protection of the vulnerable (1). An important question for both policies has been when to lift some or all of the restrictions. A closely related question is if and when herd immunity can be achieved. Herd immunity is defined as a level of population immunity at which disease spreading will decline and stop even after all preventive measures have been relaxed. If all preventive measures are relaxed when the immunity level from infection is below the herd immunity level, then a second wave of infection may start once restrictions are lifted.

By 1 May 2020, some regions and countries reached high estimates for the population immunity level; for example, 26% of the population was infected (with a large confidence interval) in the metropolitan Stockholm region, as shown by a mathematical model (2). At the same time, population studies in Spain showed that in the second half of May 2020, >10% of the population of Madrid had antibodies for coronavirus disease 2019 (COVID-19) (3). It is debatable whether (classical) herd immunity for COVID-19, which is believed to lie between 50 and 75%, can be achieved without unacceptably high case fatality rates (4–6).


There is then a discussion on the likely impact of vaccination on herd immunity, depending on the efficacy of the vaccine.

A figure from the paper:



The caption:

Fig. 1 Overall fraction infected over time.
Shown is a plot of the overall fraction infected over time for the age and activity structured community with R0 = 2.5 for four different preventive levels inserted 15 March (day 30) and lifted 30 June (day 135). The blue, red, yellow, and purple curves correspond to no, light, moderate, and severe preventive measures, respectively.


An interesting read, I think.

Have a nice weekend.

An honorable retraction of a highly cited paper on renewable energy based ammonia synthesis.

When I opened up the issue of Science this morning, I came across this rather - in my opinion - honorable retraction of a six year old paper on the production of ammonia using so called "renewable energy." (Ammonia, the synthesis is critical to the world food supply, is overwhelmingly synthesized using dangerous natural gas, followed by coal, as an energy source.)

The retraction is here: Retraction Stuart Licht1,*, Baochen Cui1, Baohui Wang1, Fang-Fang Li1, Jason Lau2, Shuzhi Liu1 (Science, Vol. 369, Issue 6505, pp. 780 14 Aug 2020)

Many, most, retractions involve some level of fraud, but I don't think this is the case here; the paper may represent an honest mistake, although it does appear that the origins of the mistake were uncovered in other labs.

The full (brief) retraction text:

We have obtained new evidence, 6 years after the publication of our Report “Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3” (1), that there is a trace NOx− impurity in the nanoscale Fe2O3 that was unknown at the time. We no longer have the original nanoscale Fe2O3, and manufacturers' content levels of impurities in chemicals may vary over time. However, recently purchased nanoscale Fe2O3 per gram contains 0.0005 g N as NOx−, and an 15N2 isotopic tracer analysis conducted by Wenzhen Li, Yifu Chen, and Hengzhou Liu at Iowa State University; Shuang Gu at Wichita State University; and author S.L. suggests that this trace impurity, rather than N2, is the major nitrogen reactant in the observed ammonia synthesis. We are retracting the original Report, and we encourage exploration of an N2 to NOx− intermediate to ammonia pathway, rather than direct elemental nitrogen pathway, to ammonia synthesis. All observed stimulation of ammonia generation with these (likely NOx−-containing) nanoscale Fe2O3 materials, as well as all thermodynamic calculation results, remain accurate as documented in the original Report.


I have not looked into this paper to any extent, but apparently, according to Retraction Watch, it was highly cited, being in one of the most prestigious journals in the world:

Authors retract highly cited 2014 Science paper

The authors of a 2014 paper in Science have retracted it, after becoming aware that impurities in the chemicals they used for their experiments may have generated the apparent findings.

The paper, “Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3,” has been cited 323 times, according to Clarivate Analytics’ Web of Science, earning it a “hot paper” designation. According to a summary of the work, “the protocol points to a way to produce ammonia from purely renewable resources.”



Using the Carbon in Phytoremediation Grasses to Remediate Heavy Metal Brownfields to Make Biofuel.

Like Joe Biden's search for a woman to be his VP candidate - Kamala Harris is clearly outstanding given the group from which she was selected - he current issue of ACS Sustainable Chemistry & Engineering is an embarrassment of riches, at least for me with my particular set of interests in the future of the world I will leave soon enough. The paper among this rich set that I choose to discuss this morning, as I have a little free time to myself having taken the day off, is this one: Valorization of Phytoremediation Byproduct via Synthesis of Biodiesel from Cockspur Grass (Echinochloa crus-galli) Seed (Sungyup Jung, Minyoung Kim, Hyeran Moon, Young-Kwon Park, Jörg Rinklebe, Chang-Jin Park, and Eilhann E. Kwon, ACS Sustainable Chem. Eng. 2020, 8, 31, 11588–11595)

In terms of full disclosure, about 20 years ago I had a semi-serious interest in going into the biodiesel industry, but thankfully thought better of it. I now understand that biodiesel, like most of the so called "renewable energy" strategies that were supposed to address climate change but didn't, aren't and won't, has proved to be destructive to the environment. One still can't say that freely among my fellow political liberals, but facts are facts and facts matter. The primary reason behind this destructive aspect is connected with land use, in particular the destruction of rain forests to use the land for palm oil plantations; one of the larger drivers of climate change besides the criminal habit of mining dangerous fossil fuels and dumping the waste directly into the atmosphere is land use changes.

But as we address the issue of land use - if we address the issue of land use, we should recognize that there is a considerable amount of land that has been functionally destroyed because of contamination with various industrial by products. Some of these by products are organic molecules, notably halogenated organic molecules like PCB's, PBDE's, PFOS, PFOA...ad infinitim but in other cases they are heavy metals.

An area for remediating contamination of land that has received considerable attention is phytoremediation, which depends on plants that concentrate the contaminants in their biomass, thus removing it from the contaminated areas. This is related to the biomagnification of pollutants, like for instance, the volatile neurotoxic coal waste mercury in seafood, and other foodstuffs. Mercury of course is responsible for the madness of hatters that was captured in Alice in Wonderland. (I often speculate to myself that the intellectual decline we are seeing so well represented by Trump Republicans and many other similar types around the world is not related to the wide distribution of neurotoxic heavy metals, in particular mercury, lead and cadmium.)

Anyway, this cool little paper caught my eye, because my primary environmental focus is process intensification, a contention that there should be no such thing as "waste" at all if future generations are to have even a remote shot at cleaning up the mess we left for them with all our wishful thinking, selfishness and generalized bullshit.

From the introduction to the paper:

Hazardous inorganic/organic matter from diverse anthropogenic activities (e.g., mining, urban development, and manufacturing) causes continuous contamination of soils and nearby streams.(1) As toxic pollutants are slowly accumulated in the environment, people are exposed to harmful substances,(2,3) which could result in adverse health effects.(4) The European Environmental Agency estimates that up to 3 million sites are polluted in Europe and that approximately 250,000 sites would require soil remediation.(5) In the United States, there are more than 1,335 Superfund sites as of February 2020.(6) To remediate contaminated soils, various treatments (i.e., physical, chemical, and biological methods) have been developed,(7) and the choice of a specific technique depends on the types of pollutants present in the soil.(7) Among them, phytoremediation has gained considerable attention as an ecofriendly measure for soil bioremediation considering that it uses plants to extract, sequester, and detoxify pollutants.(8) Although this approach is considered as an environmentally benign process for soil remediation, it produces contaminated plants. Improving the valorization of contaminated biomass from phytoremediation sites(9) would offer a further practical way to conserve natural resources and minimize the environmental impacts by applying the concept of life cycle assessment (LCA).(10)

Biomass collected from phytoremediation sites can be valorized for biofuel production, and this approach also serves as a CO2 mitigation measure.(11) In detail, global energy consumption in 2018 reached to 14 billion tons of oil equivalent,(12) with more than 80% generated from fossil resources.(13) The heavy reliance of energy consumption on fossil resources has become the main contributor of increased atmospheric concentrations of CO2.(14) Nonetheless, substantial efforts have been made over the last few decades to reduce atmospheric CO2 levels.(15,16) Among them, energy production from a carbon neutral resource (i.e., biomass) has been gaining attention because the intrinsic carbon neutralities can balance atmospheric CO2 levels.(17) As biomass is the only carbon-based material among various renewable energies (e.g., photovoltaic, wind, hydroelectricity, tidal, and others), converting biomass into chemicals (including biofuels) based on the concept of biorefinery has also been spotlighted.(18,19)


Very often, far too often for my taste, one sees in the scientific literature the claim that "photovoltaic, wind, hydroelectricity, tidal, and others" are sustainable technologies. They are not. The reason is physics, the extremely low energy to mass ratio of the materials required to make them operative, and the vast amounts of land they are required to consume through destruction, contamination, or simply industrialization. If we are to save the world, in my opinion, these obeisances have to stop.

Anyway...anyway...

It is true that biomass is a potentially sustainable way - even though as practiced now it actually records a higher death toll than Covid-19 - to capture carbon dioxide from the atmosphere, so it is not wise to throw the baby out with the bath water.

Biodiesel, which is currently made on an industrial scale, is composed of "FAME" for Fatty Acid Methyl Esters. All fats are basically triesters (and sometimes diesters or monoesters) of fatty acids, straight carbon chains terminating in a carboxylic acid group, with the trialcohol glycerol. The biodiesel process is to hydrolyze these triesters, and reesterify them with methanol, methanol being a chemical produced in large quantities - on a hundred million ton scale per year - from dangerous natural gas. I believe that methanol, and in particular the symmetric ether made from it, dimethyl ether, DME, is the key to a sustainable future, albeit only if made from the hydrogenation of carbon dioxide not obtained from dangerous natural gas.

More from the authors about their work:

Based on these rationales, this study investigated biodiesel synthesis from a phytoremediation byproduct, for achieving two goals: (1) phytoremediation using a nonedible biomass, available for mass production, and (2) biodiesel production from the contaminated phytoremediation species. In this study, cockspur grass (Echinochloa crus-galli) was used as a model compound. The cockspur grass was chosen because of its rapid proliferation and ability to translocate heavy metal(loid)s from contaminated sites. It is a well-known crop mimicry, that has evolved through artificial selection to resemble features of domestic plants, particularly rice.(24) The grass is a widely distributed nonedible weed, which grows faster than rice.(25) The undesired growth of cockspur grass in a rice paddy can consume a considerable amount of nutrients for rice,(26) suggesting the potential for fast translocation of heavy metal(loids) into the grass. In addition, the cockspur grass seeds can spread and proliferate easily with the production of 40,000 seeds per plant annually.(27,28) Because of these features, the phytoremediation potential of heavy metal(loid)s was tested while monitoring the growth of cockspur grass


Good stuff, I think.

Some pictures from the paper reflecting the results of their study:



The caption:

Figure 1. Absolute amount of heavy metal(loid) uptake by cockspur grass grown in (a) deionized water (DI) and (b) 6 ppm of heavy metal(loid) solution. Each solution was replaced with a fresh one every week.




The caption:

Figure 2. Removal of heavy metals over a three-week period.


For the preparation of biodiesel the grass seeds were thermolyzed, that is, treated with heat in the absence of oxygen. The seeds were heated to temperatures of 900°C at a ramp rate of 10°C in a TGA device (thermogravimetric analytical device). This is not highly scaled chemistry: It is effectively microscale. Nonetheless, if the process were to scale, sustainable heat of 900°C is obtainable from nuclear energy in a carbon neutral setting, with such temperatures allowing for process intensification, allowing for the production of, for example, electricity as a side product.

More pictures:



The caption:

Figure 3. (a) Mass changes of cockspur grass seeds (red) and lipid extracted from the seeds (black) and (b) differential thermogram (DTG)


In my old age I have come to love thermoanalytical chemistry.

The next graphic shows the interesting fact that some of the fatty acids in this plant's seeds are unsaturated acids. This suggests their use to make other important industrial chemicals besides biodiesel.



The caption:

Figure 5. (a) Total FAME yield and (b) relative FAME compositions obtained from transesterification of cockspur grass seeds with silica and methanol.




The caption:

Figure 5. (a) Total FAME yield and (b) relative FAME compositions obtained from transesterification of cockspur grass seeds with silica and methanol.


The authors chose to evaluate alcohols other than methanol for esterifying the fatty acids.

When I thought about biodiesel as a kid, I always thought about mixed alcohol waste streams in lieu of methanol. (These choices can have some problematic issues in diesel engines but are perhaps useful in the displacement of dangerous petroleum based home heating oil with biodiesel. Dangerous home heating oil and dangerous diesel fuel are identical chemically, except for the dyes added to home heating oil to prevent its use for tax avoidance diesel fuel.



The caption:

Figure 6. (a) Total FAAE yield and (b) relative FAAE compositions obtained from transesterification of cockspur grass seeds with different alcohols at 390 °C.


An excerpt from the author's conclusions:

This study examined the feasibility of cockspur grass as a phytoremediation plant species for heavy metal(loid) translocation by a laboratory scale hydroponic experiment. In an aqueous solution containing heavy metal(loid)s, cockspur grass was continuously grown with translocation of the heavy metal(loids) from the aqueous solution into the plant. During cockspur grass growth in the heavy metal(loid) solution, its decomposition was initiated only after 3 weeks of growth. Consequently, the control of a maximum amount of heavy metal uptake by each plant should be considered for the continuous growth of cockspur grass and adsorption of heavy metal(loid)s. Noncatalytic transesterification of cockspur grass seeds was initiated at ≥280 °C, and the yield of biodiesel reached up to 98% at 390 °C. Notably, approximately 11.6 wt % of the lipid content in cockspur grass seed was estimated by the TGA test and the Soxhlet extraction test. The biodiesel yield decreased at ≥400 °C, and such a trend was ascribed to thermal cracking of biodiesel...

The authors do not much discuss the fate of the metals removed from the soil. Among the other crimes we have committed against all future generations is the depletion of high grade ores of several important elements in the periodic table. It seems to me that much of the world's future energy requirements will thus involve recovery of elements from dilute sources, often the waste piles we so selfishly left. Figures 1 and 2 give a feel for the amount of metals that might be recovered from brownfields.

It's an interesting little paper; I enjoyed thinking about it very much.

I trust you will have a safe and pleasant weekend under the circumstances resulting from the grotesque mismanagement of our safety by the dogma driven fools in the Republican Party. In particular, I hope you will revel in the thought of our superb candidates, Joe and Kamala, in taking the reins and repairing whatever can be repaired after all this willful destruction,.

Steminists.

I was referring to a correction paper in the recent issue of Chemical Reviews and following it around lazily, I came across this interesting and inspiring site for women scientists working at UC Berkeley.

Steminists

What I found particularly interesting is some examples of women who entered the university in non-science majors, and stumbled into science after taking a math class or something of that nature.

For example, here is the graduate student Rachel Woods-Robinson who is a third year graduate student in Applied Physics at UC Berkeley who entered ULCA as a college freshman hoping to major in playing the trombone.

Recently I had a conversation with a young woman who complained that during interviews for her admission to graduate school, people kept telling her that she was a strong candidate because she is a woman of color. She didn't think it was right, felt that she was privileged. (I happen to know that she was also privileged by coming from a wealthy family, but I didn't go there.)

(She shares ethnicity with 50% of our fabulous VP nominee.)

Being an old man - an old white man with a white wife and two white sons - I told her that we all have opportunities based on our backgrounds: My sons for instance got to go to better schools than my wife did - she went to an inner city school - and that was an "unfair" advantage for them.

We in this country are working to smooth out the obstacles before each of us, and if it was a little more difficult for my son to get into an engineering program than it was for some women of color because they are women of color, well, that evens things, doesn't it?

It is not why we have opportunities, I said, but what we do with them when we get them.

Anyway, it strikes me as wonderful that these young STEM students are celebrating being women STEM scientists.

We need more of this, not less of it.

In honor of our wonderful VP candidate...Let's do Frank...

I can hand carry my absentee ballot to the Board of Elections and Circumvent Trump's Destruction...

...of the Post Office.

Concerned about the politicization of even the US Post Office, I emailed my commissioners. Here is the exchange:

Dear Mr. XXXXXX:

You are entitled to deliver your Mail-In Ballot to the Board's Office and you may utilize any secure drop box located throughout the County. The list of drop boxes to place the ballot in will be updated prior to the November Election. Please note that if you and your family elect to hand deliver Mail-In Ballots to the Board, the ballot must be completed prior to arriving at the window. The Staff will have a form to complete to confirm your delivery.

Anthony R. Francioso
Mercer County Board of Elections

From: XXXX <XXXX@gmail.com>
Sent: Saturday, August 8, 2020 12:37 PM
To: boardofelections mercercounty.org <boardofelections@mercercounty.org>; Corrigan, Mary <mcorrigan@mercercounty.org>; Francioso, Anthony <afrancioso@mercercounty.org>
Subject: Questions connected with absentee ballots.

Dear Commissioners:

It has become clear that the US Post Office is under attack in connection with the election, and efforts are being made to politicize it by the officials in the current federal government.

In connection with my personal responsibility to help our democracy survive, I want to be sure my vote will be counted and not trashed or deliberately "lost."

As such, can I and my family request an absentee ballot and hand deliver the filled out ballots directly to the board of elections?

Thanks in advance for your answer.

Best regards,

XXXXX
Such and Such Road.

Some town somewhere, NJ ZZZZZ

This is what I'm going to advise all four Biden voters in my family to do.

Liquid/Liquid Extraction Kinetics for the separation of Americium and Europium.

The paper I'll discuss in this post is this one: Liquid/Liquid Extraction Kinetics of Eu(III) and Am(III) by Extractants Designed for the Industrial Reprocessing of Nuclear Wastes (T. H. Vu, Jean-Pierre Simonin*, A. L. Rollet, R. J. M. Egberink, W. Verboomm AE Enschede,
M. C. Gullo, and A. Casnati, Ind. Eng. Chem. Res. 2020, 59, 30, 13477–13490.)

I have come to consider americium as a critical nuclear fuel if we are ever to get serious about addressing climate change, something about which clearly are not at all serious.

(Solar cells and wind turbines haven't cut it, aren't cutting it and won't cut it. The reason is physics, the extraordinary low energy to mass ratio of these systems which leads to them being purely and totally unsustainable, and in fact, environmentally odious.)

The advantages of americium nuclear fuel include these:

1) The melting point of the metal, while not as low as that of plutonium, is sufficiently low to be accessible for containment for long periods of time. The metal also has a very high liquid range, comparable to that of neptunium and gallium.

2) The critical mass in the fast neutron spectrum (which I regards as a superior spectrum) is much higher than it is for plutonium for the two most common isotopes, Am-241 and Am-243. I discussed these critical masses in this space here: Critical Masses of the Three Accessible Americium Isotopes. The continuous recycling of plutonium will lead to rising critical masses because of the increases in the proportion of Am-243 with respect to Am-241.

3) Over a long period of operation Americium will produce two valuable plutonium isotopes that are critical for denaturing weapons grade plutonium, Pu-238 and Pu-242.

4) Considerable inventories of Americium exist and are readily available owing to the environmentally disastrous fear and ignorance that have prevented the prompt recycling of nuclear fuels.

5) The accumulation of Curium-242, Curium-244, and Plutonium-238 in americium based fuels, besides generating heat, will also generate supplies of the important industrial gas helium, a gas which is rapidly being depleted from mined sources.

6) Over the long term, the decay of Pu-238 will produce important supplies of U-234, which will eliminate, largely, the need for isotopic enrichment of uranium (particularly when conducted in concert with the use of thorium based U-233.)

Besides these advantages, it is possible, but not known to my knowledge, that liquid americium metal will prove to be less corrosive than liquid plutonium. That would simplify things a bit, although in my opinion, the corrosive nature of plutonium is a surmountable problem.

The evolution of an americium based liquid metal fuel over a period of decades will result in an Americium-Plutonium-Uranium alloy. Here is a (computationally derived) ternary phase diagram of this alloy showing liquidus curves:



The caption:

Fig. 7. Predicted liquidus projection of the U-Pu-Am system. Along the dashed curve the liquid alloy decomposes to the U-rich and Am-rich b.c.c, phases..


Source: Ogawa, Journal of Alloys and Compounds, 194 (1993) pp. 1-7.

As the fuel evolves, the melting point decreases, and with it, the expectation of sufficiently liquid fuels to allow for in line fuel processing, with the caveat being the effect of fission products.

Europium is a fission product, a relatively minor fission product, but a fission product all the same. It is always to be expected to be present in used nuclear fuels, both from the capture of neutrons in samarium isotopes as well as a direct fission product. Overall, one would expect, qualitatively for europium to relatively depleted because the two natural isotopes Eu-151 and Eu-153, high neutron capture cross sections, at least in the thermal spectrum, as do the two fairly long lived radioactive isotopes and their nuclear isomers, Eu-152 and Eu-154, with half-lives respectively for their low energy isomers, of 13.5 and 8.6 years. Although small quantities of these isotopes probably represent burnable poisons, and may have some utility as such, it may be, and most likely is desirable to remove europium from americium.

This brings me to the paper under discussion. Liquid/liquid extraction (often abbreviated "LLE" ) has been the most common approach to reprocessing used nuclear fuels. I don't necessarily endorse these as being likely to be the best approach, but nobody cares what I think anyway. Almost always, these extractions require agitation and worse, the use of solvents obtained from dangerous fossil fuels. It has occurred to me in recent years, particularly in light of the development of low temperature ionic liquids, that there may be other ways to exploit mass transfer across liquid interfaces, and thus this paper is of potential interest for me as I develop my generally useless thinking.

From the introductory text of the paper:

The reprocessing of nuclear wastes resulting from spent nuclear fuel is a worldwide topic of utmost importance in the nuclear industry and for the society itself. Various processes, generally based on liquid/liquid (L/L) extraction stages, have been proposed with the aim of reducing the volume, heat, and radiotoxicity of highly radioactive waste (plutonium and americium in particular) for their disposal in a geologic repository.(1) These processes involve the separation of the most problematic radioactive elements in the wastes.

Various strategies have been developed worldwide for the reprocessing of used fuel. An overview of the main solvent extraction processes(2) (besides Europe) is presented in Table 1. References are indicated in the table that give more details on the policies of the countries in this domain.


Table 1:



The text continues:

In Europe, this topic has been tackled with determination through the financing of successive European EURATOM projects since the early 90’s: NEWPART, PARTNEW, EUROPART, ACSEPT, SACSESS,(7) and now GENIORS (GEN IV Integrated Oxide fuels Recycling Strategies).(8) The European approach was centered around the use of selective extractants and molecular diluents that would generate a minimal amount of secondary waste. A feature of this strategy is the use of chemicals that only comprise the C, H, O, and N atoms (often referred to as the CHON principle(9)), which makes them suitable for subsequent incineration.
Reference aqueous separation process routes have emerged from these in-depth studies. They are depicted in Figure 1.(10,11)


Figure 1:



The caption:

Figure 1. Main routes of the European partitioning process strategy envisaged for the recycling of actinides (An) from used fuel (Ln = lanthanides). EXAM = extraction of americium.


Some descriptive text:

One route uses the GANEX (Grouped Actinide EXtraction) process(12,13) in which uranium is separated from the waste in a first step, and then, transuranic actinide elements are isolated (Np, Pu, Am, and Cm) from all fission products.
In the other route, the PUREX (plutonium, uranium, reduction, and extraction) process,(14) first implemented in the Manhattan project, is employed for the separation of uranium and plutonium from other fission products by using tributyl phosphate (TBP) as the extractant. The COEX process is a modified version of PUREX. Then, the DIAMEX (DIAMide EXtraction) process developed at CEA (Commissariat à l’Energie Atomique) in France may be used. It consists of the co-extraction of trivalent minor actinides [MA’s, mainly composed of americium(III) and curium(III)] and lanthanides (Ln’s) from a PUREX raffinate by employing a malondiamide extractant. Although they constitute less than 0.1% of the initial spent fuel mass, the MA’s (especially neptunium, americium, and curium) will be the main contributors to the radiotoxicity (and heat generation) after a three-century storage of high-level radioactive liquid waste (obtained after the PUREX stage).


The authors here are referring to the "storage" of so called "nuclear waste." By contrast, I speak of the recovery of nuclear resources. They are also speaking of "once through" thermal fuel, largely, and not continuously recycled actinides.

These caveats aside - most of humanity has been trained to think in this way, of waste rather than resources and this is clearly a fatal way to think, fatal to the future.

In a continuous actinide recycling program, some calculations show that it is possible to obtain americium alone in concentrations of close to 1.5% (cf. Ref: Nuclear Reactor Physics, William E. Stacy, Wiley and Sons 2001. pg.234). In a world in which we we did not use any dangerous fossil fuels, where we let our rivers run free, where we did not convert our wilderness into industrial parks for wind turbines, destroy rain forests for biofuels, generate millions of tons of toxic electronic waste for solar cells, we would need, in order to produce 600 exajoules of energy per year that we use as of recent times, we would require the fission of about 7,500 tons of plutonium (or other actinides) per year. This implies about 100 MT of americium would be available per year, a significant quantity of potential industrial importance. There may not be a lot of americium, but for the reasons given above, it may prove a useful fuel.

The authors use a device known as "rotating membrane cell" which is pictured here:



The caption:

Figure 2. RMC technique. Left: View of the cell with the membrane glued at the bottom. Center: Cell rotating in the outer phase. Right: Sketch of the technique.


The technique is closely related to solvent extraction techniques used in the industry, with several extractants in a commercially available mixture of dodecane isomers known as "TPH" containing a small amount of n-octanol, whereupon the solvent is known as "TPH-O." The extractants utilized in these solutions are shown in the following figure:



The caption:

Figure 3. Chemical structures of the molecules used in this study (SO3-Ph-BTP in tetravalent ionic form, counterion: Na+).


The membranes employed are commercially available, one being a hydrophilic membrane, the other hydrophobic:

Two types of membranes were purchased from Merck Millipore: the hydrophilic Omnipore PTFE membrane (JHWP04700, manufacturer’s data: pore size 0.45 μm, porosity of 80%) was employed to contain aqueous solutions, and the hydrophobic Durapore PVDF membrane (HVHP04700, manufacturer’s data: pore size 0.45 μm, porosity of 75%) was employed for organic solutions. The porosity values were also measured by impregnating membranes (glued on a plastic cylinder) with TPH and by measuring the corresponding mass of diluent. The membrane thicknesses, L, were measured by using a digital micrometer.


There is considerable discussion in the paper of the technique, and there is not time to describe all of it in detail. However the separation efficiency and speed are significant.

The last figure in the paper shows distribution coefficients for one system evaluated:



The caption:

Figure 7. Aq/org distribution ratios (1/K, left scale), and separation factor [SF(Am/Eu), right scale], of Eu(III) and Am(III) for an organic 0.2 M TODGA solution in TPH-O and an aqueous 0.5 M HNO3 solution as a function of SO3-Ph-BTP concentration in the aqueous phase up to 40 mM. ( ● ) = Eu(III); ( ○ ) = Am(III).


The authors conclude, noting that the purpose of their work is to provide input for further modeling and development of new systems.

...Extraction and stripping of Eu(III) and Am(III) were studied for various concentrations of nitric acid and TODGA, in mixtures of CyMe4-BTBP with TODGA, and in the presence of the aqueous ligands SO3-Ph-BTP and PTD. It was somewhat striking to find that TODGA is not surface-active at the interface between nitric acid and TPH-O, which is in contrast with the case of TODGA in n-dodecane.

The kinetic data obtained in this work will be used as input parameters in simulation codes (such as, e.g., PAREX, developed at CEA(64,65)) for a modeling of separation processes carried out in extractors (e.g., centrifugal) that operate with a short contact time between the phases.

The experimental results, obtained with TODGA and the two aqueous stripping ligands, show that faster transfer kinetics are associated with higher partitioning for Am(III) over Eu(III). This favorable outcome bodes well for future efficient actinide/lanthanide separation in the nuclear reprocessing industry.


My personal feeling is that we need to move beyond nitric acid dissolution of used nuclear fuel, which is a feature of the chemistry herein.

I believe the cleaner option for future nuclear fuel reprocessing is to conduct some of it in line using techniques including but not limited to distillation. There are also possibilities, some of which were briefly explored in the 1950's, to utilize liquid/liquid extractions in line using inorganic liquids.

However, it may be that liquid/liquid interfaces may be important at some point in future techniques. We need to take a deeper look at molten salt based separations, included but not limited to organic ionic liquids. Much attention is being paid to these substances. Finally a driving force for both separations and dissolution may not need to involve mechanical forces. Electrochemical techniques, including those involving liquid membranes are worthy of consideration.

There are really a wealth of options for the treatment of nuclear fuels and the recovery and use of the radioactive and non-radioactive materials therein. These materials are probably, in my view, the best shot we have to save the world.

I hope your weekend was pleasant as much as it was safe.

Susan Collins.

The Genome of the Last Surviving Member of an Order from which Dinosaurs, Birds, Mammals...

...and modern reptiles evolved has been sequenced.

The paper to which I'll refer is this one: The tuatara genome reveals ancient features of amniote evolution (Gemmel et al., Nature, https://doi.org/10.1038/s41586-020-2561-9).

An amniote is an animal whose embryonic development takes place in an amiotic fluid surrounded by a membrane called a chorion. This class of animals includes all reptiles, birds, and mammals.

The paper is open sourced, anyone can read it. It describes the last member of a class of animals which once dominated the Earth before branching out to evolve as dinosaurs, birds, modern reptiles, and mammals including that somewhat destructive animal the human being.

An excerpt from the abstract:

The tuatara (Sphenodon punctatus)—the only living member of the reptilian order Rhynchocephalia (Sphenodontia), once widespread across Gondwana1,2—is an iconic species that is endemic to New Zealand2,3. A key link to the now-extinct stem reptiles (from which dinosaurs, modern reptiles, birds and mammals evolved), the tuatara provides key insights into the ancestral amniotes2,4. Here we analyse the genome of the tuatara, which—at approximately 5 Gb—is among the largest of the vertebrate genomes yet assembled. Our analyses of this genome, along with comparisons with other vertebrate genomes, reinforce the uniqueness of the tuatara. Phylogenetic analyses indicate that the tuatara lineage diverged from that of snakes and lizards around 250 million years ago.


From the introduction:

The tuatara (Sphenodon punctatus)—the only living member of the reptilian order Rhynchocephalia (Sphenodontia), once widespread across Gondwana1,2—is an iconic species that is endemic to New Zealand2,3. A key link to the now-extinct stem reptiles (from which dinosaurs, modern reptiles, birds and mammals evolved), the tuatara provides key insights into the ancestral amniotes2,4. Here we analyse the genome of the tuatara, which—at approximately 5 Gb—is among the largest of the vertebrate genomes yet assembled. Our analyses of this genome, along with comparisons with other vertebrate genomes, reinforce the uniqueness of the tuatara. Phylogenetic analyses indicate that the tuatara lineage diverged from that of snakes and lizards around 250 million years ago.

It is also a species of importance in other contexts. First, the tuatara is a taonga (special treasure) for Māori, who hold that tuatara are the guardians of special places2. Second, the tuatara is internationally recognized as a critically important species that is vulnerable to extinction owing to habitat loss, predation, disease, global warming and other factors2. Third, the tuatara displays a variety of morphological and physiological innovations that have puzzled scientists since its first description2. These include a unique combination of features that are shared variously with lizards, turtles and birds, which left its taxonomic position in doubt for many decades2. This taxonomic conundrum has largely been addressed using molecular approaches4, but the timing of the split of the tuatara from the lineage that forms the modern squamates (lizards and snakes), the rate of evolution of tuatara and the number of species of tuatara remain contentious2. Finally, there are aspects of tuatara biology that are unique within, or atypical of, reptiles. These include a unique form of temperature-dependent sex determination (which sees females produced below, and males above, 22 °C), extremely low basal metabolic rates and considerable longevity2.


A graphic from the paper:



The caption:

a, The tuatara, (S. punctatus) is the sole survivor of the order Rhynchocephalia. b, c, The rhynchocephalians appear to have originated in the early Mesozoic period (about 250–240 million years ago (Ma)) and were common, speciose and globally distributed for much of that era. The geographical range of the rhynchocephalians progressively contracted after the Early Jurassic epoch (about 200–175 Ma); the most recent fossil record outside of New Zealand is from Argentina in the Late Cretaceous epoch (about 70 Ma). c, The last bastions of the rhynchocephalians are 32 islands off the coast of New Zealand, which have recently been augmented by the establishment of about 10 new island or mainland sanctuary populations using translocations. The current global population is estimated to be around 100,000 individuals. Rhynchocephalian and tuatara fossil localities are redrawn and adapted from ref. 1 with permission, and incorporate data from ref. 2. In the global distribution map (c, top); triangle = Triassic; square = Jurassic; circle = Cretaceous; and diamond = Palaeocene. In the map of the New Zealand distribution (c, bottom); asterisk = Miocene; cross = Pleistocene; circle = Holocene; blue triangle = extant population; and orange triangle = population investigated in this study. Scale bar, 200 km. Photograph credit, F. Lanting.


It's well worth a look, and again, open sourced. It's well worth a look.

If interested, enjoy...

I wish you a safe, healthy and pleasant weekend.
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