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NNadir

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Member since: 2002
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Oxygen Isotope Ratios at the Trinity Nuclear Test Site and Laser Fluorination Extraction.

Recently I have been interested in the properties of actinide nitrides - which feature very high melting points - and their use in multiphasic nuclear reactors featuring low melting plutonium/neptunium eutectic liquid fuels, reactors about which I've been musing for some time. It seems to me that these types of reactors could be designed to run, without refueling, for more periods well longer than half a century in a "breed and burn" scenario, where the actinide nitride is UN, uranium nitride consisting of unreacted uranium in used nuclear fuels or depleted uranium, thus eliminating, ultimately, the need for mining anything, oil, gas, coal and, um, uranium for a very long time, for generations.

Nitrogen consists of two natural isotopes, N-14 and N-15 which represent respectively, 99.6% and 0.4% of the content of natural nitrogen. Interestingly Nitrogen-14, the most common isotope by far is, parenthetically, the only stable nuclide in the entire table of nuclides to feature both an odd number of neutrons and an odd number of protons.

In a neutron flux, N-14 undergoes a 14N[n,p]14C reaction during which it is converted into radioactive carbon-14. Carbon-14, as I recently confirmed in a search of the literature, itself has a very low neutron capture cross section which means that it would be extremely useful in actinide carbide fuels which also have extremely high melting points, as well as in known carbide refractories such as silicon carbide, titanium carbide and carbon containing MAX phases. Low capture cross section elements in materials increase neutron efficiency and thus breeding ratios.

(Any attempt to reverse the oxidation of carbon to fight climate change - a formidable engineering task to be sure - will require access to extremely refractory materials to provide high temperatures to produce hydrogen from water thermochemically and carbon monoxide from carbon dioxide, also thermochemically.)

Most of the nuclear scientists whose lectures I have the opportunity to attend are fusion people. They are interested in various cross sections of the light elements, whereas generally, I am not, except as described above, in the case of there presence in fusion fuels. (While their work is fun, none of it will become practical in any time remotely capable of addressing climate change; there are far too many practical issues to address for which they only have a loose approach to addressing.)

I should pay more attention though to the light elements though; their nuclear behavior is important in both fusion and fission systems.

A few years back, in some of my desultory wanderings in the scientific literature, I came across an interesting paper relating to the capture cross sections of light elements. Specifically, the material being tested was "trinitite," the glass material that was first observed after the first nuclear weapons test at the Trinity test site in 1945.

That paper is here: Oxygen Isotope Composition of Trinitite Postdetonation Materials (Koeman et al, Anal. Chem., 2013, 85 (24), pp 11913–11919)

To my personal surprise, they find that the oxygen isotopic ratios at the Trinity test site are not significantly altered, indicating that there was very little neutron capture resulting from the high neutron flux associated with the test, which was, after all, a ground test. The oxygen isotopic ratios were consistent with the natural isotopic fractionation that goes on during the formation of various minerals at the site, which consists of arkosic sands.

(A marker for the neutron flux was the radioisotope 152Eu, which formed from neutron capture in natural 151Europium in the sands. This isotope has a half-life of 13.54 years, and a little more than 2% is still present today at the test site.)

What is also very interesting is the analytical technique that was utilized in determining these oxygen isotope ratios, a beautiful extraction technique called "laser fluorination." This technique is described in the following paper authored by French scientists: IR Laser Extraction Technique Applied to Oxygen Isotope Analysis of Small Biogenic Silica Samples (Alexandre et al Anal. Chem., 2008, 80 (7), pp 2372–2378).

In this technique oxygen is liberated from a sample by oxidation by the powerful oxidant BrF5.

A description from the paper:

Oxygen Extraction Using the IR Laser-Heating Fluorination Technique and δ18O Measurement.

Molecular O2 was extracted from silica in a laser extraction line close to the one described by Sharp.35 A Merchanteck 30 W CO2 IR laser was used. The nickel sample holder was loaded in the sample chamber, prefluorinated with 50 mbar of BrF5 for 1 h and pumped for several hours. In an atmosphere of 100 mbar of BrF5, samples were preheated for 20 s with a 2000 μm diameter laser beam, increasing the power of the laser beam until the particles start moving:  from 0% to 3.6% of the laser full power for fine quartz, 2.2% for diatoms, and 2.6% for phytoliths. The laser emission was stopped after 30 s. Quartz grains and phytoliths were then heated with a 2000 μm diameter laser beam at 30−35% of its full power (11−12 W), starting at the center and slowly moving the laser beam following concentric circles until a bowl of liquid silica formed. Diatom samples were heated with a 2000 μm diameter laser beam, starting at the edge and progressively increasing the laser power from 0% up to 30−35% of its full power (11−12 W), slowly moving the laser beam following concentric circles. For all samples, when a bowl of liquid silica formed, the laser beam was then focused at 1000 μm of diameter until the liquid disappeared. The remaining particles were heated with a focused 200 μm of diameter laser beam. Laser emission was stopped when no more reaction to the laser beam occurred. Some residues remained for the diatom subsamples. They decreased from KYO 40 to KYO 90. These protocols prevented ejecta.

The liberated oxygen was then purified and trapped by adsorption in a microvolume filled with 13X molecular sieve and cooled in liquid nitrogen. The oxygen gas was then heated at 100 °C and directly sent to the sample bellow of the dual-inlet mass spectrometer (ThermoQuest Finnigan Delta Plus).

In order to get a sufficient 34/32 signal (2−3 V), the oxygen from 0.3 mg aliquots was concentrated in the mass spectrometer in an autocooled 800 μL microvolume filled with silica gel and directly connected to the dual-inlet system.


Cool I think, at least if you think a certain way. Analytical inorganic chemistry can be very beautiful.

I wish you a happy and prosperous New Year.

Bill Clinton's book review of Chernow's "Grant."

I have long felt that the Presidency of Ulysses S. Grant, often rated by academic historians as disastrous and failed, needs serious reassessment, which happily is now going on, particularly at a time when we have a "President" who is actually worse than Andrew Johnson, one of the worst Presidents ever, who was impeached but not convicted.

I happen to believe that Ulysses S. Grant was a great President, the second most important President of the 19th century, responsible for one of the most important and necessary changes to the US Constitution, the 15th amendment, which happily was recently responsible for the election of Doug Jones in Alabama.

It is very unlikely that the country would have survived at all without Grant's Presidency; without him the Union victory in the Civil War would have been undone as the country lapsed into continuous guerrilla warfare.

The reassessment of the Grant's Presidency is well underway - the low ranking having been fostered on historians by an odd coalition of overt racist "lost cause" advocates and self described "reformers" - and is being advanced at an increasing pace, something that satisfies me personally very much, as I have long admired President Grant.

I wrote about my admiration of Grant elsewhere a long time ago: US Grant and the Worst President Stuff (2007)

The second President to be impeached but not convicted, and who was actually quite a good President, is of course, Bill Clinton, and interestingly, he has reviewed Ron Chernow's best selling book on the 18th President of the United States.

NY Times Book Review of Cherow's "Grant" by Bill Clinton

Clinton writes:

The Union that Grant had been instrumental in saving as a general was splintering anew even before he took his oath of office. As Chernow writes, “If there were many small things Grant didn’t know about the presidency, he knew one big thing: His main mission was to settle unfinished business from the war by preserving the Union and safeguarding the freed slaves.”

And there was a very real chance Grant, and with him the country, would fail.

For that new mission, Grant needed cabinet members, staff and advisers every bit as masterful as his wartime lieutenants. His choices were notably hit-and-miss, but his very first appointee from a Confederate state proved to be one of his best. Amos T. Akerman of Georgia, Grant’s second attorney general, was “honest and incorruptible” and “devoted to the rule of law.” When Congress created the Department of Justice the same week as his appointment, the attorney general became overnight the head of “an active department with a substantial array of new powers.” Those powers were sorely needed to fight the Klan and what Chernow appropriately calls “the worst outbreak of domestic terrorism in American history.”...

...Chernow shows a fine balance in exposing Grant’s flaws and missteps as president, and the ill-fated turn that Reconstruction took after a promising start, while making it clear that Grant’s contributions after Appomattox were as consequential to the survival of our democracy as any that came before. As Americans continue the struggle to defend justice and equality in our tumultuous and divisive era, we need to know what Grant did when our country’s very existence hung in the balance. If we still believe in forming a more perfect union, his steady and courageous example is more valuable than ever.


I almost agree.

Anyway.

In these times where racists are running wild in the Government, where corruption at a very high level is taking place, where the Government is being bankrupted by wealthy scammers and their collaborators, I think Chernow's book is very important.

I've asked Santa to buy it for me, and will be waiting up all night at the Christmas tree to yank that book out of the fat Elf's sack.

Accumulation of a very potent greenhouse gas has stopped.

Recently I was going through some papers I downloaded on the subject of the gas oxygen difluoride, OF2, which is of interest to me because of some ideas I've had about electrochemical/fluoride volatility approaches to the recovery of valuable materials from used nuclear fuels, specifically the elements ruthenium, rhodium, technetium, molybdenum, plutonium, neptunium and uranium.

To my surprise, one of the papers found by my Google scholar search and collected by me was this one: Identifying the Molecular Origin of Global Warming (Lee, Berra and Francisco, J. Phys. Chem. A, 2009, 113 (45), pp 12694–12699) which, it seemed to me, has nothing to do with nuclear fuel reprocessing or even the chemistry of OF2.

But for some reason, the gas OF2 appears in table 1 the paper with a list of gases with global warming potential, their atmospheric lifetimes, global warming potential, etc.

The atmospheric lifetime of OF2 is not listed, which is not surprising, it should be as close to zero as it can be without actually being zero. OF2 is one of the few molecules known in which a positive charge resides on the extremely electronegative atom oxygen. As such it is one of the most powerful oxidants known; it will rapidly and quantitatively oxidize water: OF2 + H2O -> 2HF + O2.

Possibly it was included because it is a powerful fluorinating agent and thus may be utilized in the production of some of the gases that are utilized to make gases like the perfluoroalkanes and hydrofluoroalkanes (HFCs) that have replaced ozone depleting chloroflouroalkanes (CFCs) banned under the Montreal Protocol in refrigeration systems, HFC's being gases that are not ozone depleting but are nonetheless global warming forcing gases.

Otherwise, almost all of the other gases in the table were familiar to me, varieties of the aforementioned CFC's and HFCs, nitrous oxide, N2O (a potent ozone depleting gas as well as a global warming forcing gas), SF6 which replaced polychlorobiphenyls (PCBs) in electronic equipment as is also used in "green" thermally insulating windows in "environmentally aware" McMansions and office buildings meeting LEED certifications...blah...blah...blah.


In contrast to the situation with oxygen, most bonds to fluorine are extremely stable, notably in the case of carbon fluorine bonds, nitrogen fluorine bonds and sulfur flourine bonds, and as a result these compounds can persist for a very long time and are only destroyed by exposure to high energy radiation, far UV, x-rays and gamma rays.

Then there in table 1 was one gas of which I'd never heard, and about which I knew zero, pentafluorosulfuryltrifluoromethane, SF5CF3.

I asked myself, what the hell is that and why is it there and what the hell do they use that for?

In the table, it is listed as the most potent global warming potential gas, said potential being 22,800 on a scale in which the dangerous fossil fuel waste carbon dioxide is defined as having a value of 1.

As for "what the hell do they use that for?" the answer is, apparently, "nothing." The gas was discovered in atmospheric samples in Antarctica in the year 2000 and reported in the journal Science: A Potent Greenhouse Gas Identified in the Atmosphere: SF5CF3 (Sturges et al Science ol. 289, Issue 5479, pp. 611-613) Since there was no known use for the gas, the authors speculated that the gas was being created in the high field electronic equipment in which SF6 was utilized by reaction with teflon components. (The HTML version of the paper is open sourced, the PDF is not.)

It turns out that the authors were wrong and cheerfully admitted as much: Emissions halted of the potent greenhouse gas SF5CF3 (Sturges et al, Atmos. Chem. Phys., 12, 3653–3658, 2012) This paper is also open sourced as a PDF, but I'll excerpt it anyway.

Immediately following publication of our article, however, an open letter to the publishing journal from the company 3M stated that “one source of this compound is as a by-product of the manufacture of certain 3M fluorochemicals” (Santoro et al., 2000). It transpired that the relevant process was electrochemical fluorination for the production of perfluorooctanyl sulphonate, (PFOS) and other fluorosurfactants, used in the manufacture of foams and stain-resist coatings.

They went on to note that these production operations were to be imminently curtailed in the USA. In a subsequent personal communication, their bottom-up emission estimates were evidently close to the global emission rate that we had deduced from observations. We have updated the time series of atmospheric measurements from our original publication, and find that SF5CF3 has ceased to increase in the atmosphere, whereas the abundance of SF6 has continued to rise unabated. This clearly demonstrates that our original supposition that SF5CF3 originates from the degradation of SF6 was incorrect, and that all evidence now points to 3M being correct in their earlier assertion and that, as they predicted, emissions of this greenhouse gas have subsequently reduced to the point where they are no longer distinguishable by observation from zero.


PFOS is a serious persistent pollutant in its own right with a seriously long lifetime. I have written quite a bit about this compound which is also only degraded by high energy radiation, more or less, although some metabolism into potentially worse pollutants has been observed. PFOS can be pretty much detected in every living thing on the planet, particularly in lipids. 3M sold it until early 2000 in the product Scotch Guard which was very popular for protecting furniture.

(Other very persistent pollutants are also related to furniture as well, the flame retardants known as PBDE's, polybromodiphenyl ethers: These are also being phased out in furniture and clothing. They are also highly stable and only degraded radiochemically.)

To the credit of 3M, once they became aware of the persistence problem they voluntarily stopped making the product, which was a big seller, rather than manufacture ersatz "science" proving it was harmless - the Exxon approach.

They also immediately and voluntarily "'fessed up" about the source of SF5CF3, as noted by authors.

It does seem, happily, that this gas will not be growing in the atmosphere, even if most greenhouse gases will continue to rise unabated because, basically, we just don't care.

Have a happy holiday season.

Have you considered the meaning of the word "worthy?"

One of the great pleasures in life is to read and re-read the works of the great historian David McCulloch, and one of his greatest books of course is John Adams. (The HBO film series based on it is also excellent.)

I was leafing through it this morning and came across this excerpt of a letter from Adams, late into his retirement, to his grandson John Smith and in these awful times bears repeating:

Have you considered the meaning of the word "worthy?" We it well...I had rather you should be a worthy processors of one thousand pounds honestly acquired by your own labor and industry, than of tens of millions by banks and tricks. I should rather you be worthy shoemakers than secretaries of states or treasury acquired by libels in newspapers. I had rather you should be worthy makers of brooms and baskets than unworthy presidents of the United States procured b intrigue, factious slander and corruption.


(cf, David McCulloch, John Adams, Simon and Schluster, 2001 pg 608-609)

The bold is mine, but is actually apropos to the present state of affairs, one of the darkest periods in American history through which I've lived, and I lived a long time.

Franklin Roosevelt had these words, written by his predecessor Adams inscribed on the mantle of the fireplace of the White House"

"May none but Honest and Wise Men ever rule under This Roof."


This has obviously failed to be true, and the White House is actively being defiled by a racist pig who obviously can neither think, read or reflect. If he ever bothered in his sneering ignorance to read these words - he would simply continuing sneering at his country using his well known contempt for humanity and his country.

Both Presidents must be rolling in their graves.

A critical issue of critical materials; my holiday science reading list.

I have 10 glorious days off from paid work this holiday, and plan to catch up on some reading for which I've had little time.

One important task will be to write to an on line friend about what I've learned about her great niece's diffuse intrinsic pontine glioma, a very dangerous (and rare) pediatric brain cancer which has been the subject of considerable research.

It's frightening, but I believe I'm an old Obama boy; I believe in hope. I'll do what I can to be of any help.

Another is to catch up on some reading about the broader challenges to humanity beyond any individual beautiful and threatened child.

Tonight in my files, I came across a highly cited paper which I have not read; it's on my holiday reading list, this one:

What Do We Know About Metal Recycling Rates? (Graedel et al, Journal of Industrial Ecology Volume 15, Issue 3 June 2011 Pages 355–366)

A few years back, around this time of year, I came across an interesting (if unappreciated) book in the New Books rack in Princeton University's Engineering Library, a sort of shrine that I visit often on my path to peace. It's this one: Thanatia

The above cited paper was in fact a reference from this book.

Thanatia s a little rapped up in this Gaia/not Gaia sort of touchy feely stuff, but I think a somewhat poetic description of a critical issue about which too little public discussion takes place.

The preface of the book, which is now in my files, states issue it addresses quite well:

The extraction of fossil fuels and mineral resources has grown exponentially since the early 20th century and far from decelerating, it is expected to increase in the coming decades. "The Limits to Growth" (Meadows et al., 1972) already alerted that if demand of metals and fossil fuels maintained the same trend, mankind would sooner or later be close to collapse. The book provoked a strong controversy between those that considered that the Earth was plentiful of non-renewable resources (technooptimists) and those who believed in the need for a rational management of the planetary mineral endowment.

Forty years on society has experienced an unparalleled economic optimism (especially in the nineties and the first few years of the 21st century) and also the biggest economic crisis since the Wall Street crash in 1929. At the same time, computers, smartphones, the electric car, renewable energies, new materials and electronic appliances are renovating the optimism for a brighter future. Yet all these technoartifacts are deeply connected to the mineral endowment of the Earth. Elements like indium, gallium, germanium, rare earths, tantalum, zirconium, cobalt, tin, precious and platinum group metals, lithium, tellurium, phosphorous, etc, are profusely used without or with only minor recycling.

How long can society survive without a rational management of these scarce resources? Today, technology is employing all elements of the periodic table and their use is growing exponentially.-Yet this fact is barely discussed in conventional ecological discourse that preferably focuses on climate change, loss of biodiversity, deforestation or ecosystems destruction.


I am, even if I believe that the popular beliefs about sustainability are actually dangerously wrong headed - as much on the left as on the right - still a kind of "techno-optimist." I once spent an afternoon chatting with Freeman Dyson after all.

But as much as in my techno-optimism I believe that dire and extreme problems can be solved, I'm less and less inclined to have faith that they will be solved.

The Christmas season in the United States is a party time: I will participate. But there is some place in it as well, for me if not for everyone, for some sobriety.

Have happy holidays and if you can squeeze in some time, read some science. It's good for you, far better than egg nog.


A Nice Discussion of the Use of Desalination Brines for the Production of Caustic Soda (NaOH).

Many years ago, in this space, back when I was still a fan of so called "renewable energy," I wrote a brief discussion of the potential use of California's Salton Sea as a tool for energy recovery and desalination.

That post is here: I offer a crazy energy idea about which I've fantasized: The Salton Sea.

Many of my energy ideas have changed since I wrote that piece 12 years ago. This was, for example, before the planetary community invested trillions of dollars in so called "renewable energy," dominated by the useless solar and wind industries.

In November of 2005, the mean concentration of the dangerous fossil fuel waste as reported at the Mauna Loa carbon dioxide observatory was 378.29 ppm. In November of 2016, the most recent posted monthly mean posted there, the concentration was 405.14 ppm.

The average for all year to year monthly comparison figures recorded as increases in the 20th century was 1.30 ppm/year. Since November of 2005 to November of 2017, the same type of average is 2.24 ppm/year.

So called "renewable energy" is a grotesque failure. It has not worked; it is not working; it will not work, if the goal is to address climate change rather than to post "feel good" stuff on the internet about how wonderful solar and wind are and how wonderful it is to subsidize the billionaire Elon Musk to the tune of billions of dollars because he's so, um, "green."

However this may be, and however much I may have changed my mind about so called "renewable energy" since 2005, I am still very concerned about our absolute indifference on this planet to address climate change. Now, as the end of my life approaches filled with existential guilt about what my generation is leaving for future generations, I am very much trying to spend some portion of my time to thinking about ways to remove carbon dioxide from the atmosphere, in other words, how future generations might, to whatever extent possible, clean up the planetary superfund site with which we've left them.

Once consequence of climate change will almost certainly involve access to clean and fresh water. We have seen this in many places on this planet, most graphically and recently for those Americans who give a shit - this would leave out anyone involved with the Trump crime family - in California, where I used to live decades ago, and where I used to think all the time about water.

It does seem to me that the only approach to addressing this issue in places like California, and for that matter in places where water supplies depend on glaciers, which they do for billions of people will involve seawater desalination.

Desalination is not, in any way, environmentally benign, however. One of the most important issues involved is of course, energy. Unless clean carbon free sustainable energy is available - I never tire of pointing out that in my opinion only nuclear energy meets this criteria - all desalination schemes will be counter productive.

The other problem with desalination concerns the resulting brine. Most schemes for desalination return the concentrated brine directly to local waters. On a grand scale this has the potential for further environmental destruction not only because of the impact on local ecosystems, but also on the further destabilization of oceanic salt gradients, which in turn further destabilize climatic and temporal weather.

Although I still favor, for certain reasons, the same thing I proposed in 2005 for the Salton Sea, formally reduced pressure distillation, over all in the scientific literature, at least in my overall impression, much of the discussion has focused on membrane separation.

A very nice overview of a potential solution for the brine problem (with some impact on the energy problem as well) was recently published in the wonderful scientific journal ACS Sustainable Chemistry and Engineering by scientists out of MIT.

The paper is here: Utilization of Desalination Brine for Sodium Hydroxide Production: Technologies, Engineering Principles, Recovery Limits, and Future Directions (John Leinhard V, et al, ACS Sustainable Chem. Eng., 2017, 5 (12), pp 11147–11162)

All of the energy ideas I've had in my lifetime involve the utilization of by products of processes - often referred to as "waste" in our common parlance - as starting materials or tools to accomplish other tasks. (Mostly this involves material by products but also can include heat.) This is why this paper so pleases me. It proposes to use a waste product (brine) to make another value added product (caustic soda, NaOH).

The introduction to the paper addresses this nicely:

Environmental and economic factors have long motivated interest in reducing the amount of brine discharged back into the ocean by seawater desalination plants. Modern designs for brine outfalls can limit adverse environmental impacts to “tens of meters” from the discharge source(1, 2) but are high cost.(3) An emerging class of solutions, broadly titled waste-to-resource, aim to reduce brine discharge by transforming it into useful compounds.(4-7)

Many previous such studies focus on recovering salts, of which the largest by mass is sodium chloride. But in many countries, NaCl exists in abundant, cheap supply as rock salt or brine, meaning any competing source must be extremely low cost. [The US Geological Survey reports average US rock salt and brine prices ranging from 38–50 USD/ton and 8–9 USD/ton, respectively, from 2011–2015.(8)] Its chemical derivatives, primarily soda ash, caustic soda (“caustic”), and chlorine, however, may be much higher value. Nearly 30% of NaCl sold in the US(8) is used as a feedstock in the chlor-alkali process to manufacture the most common of these at large scale: NaOH and Cl2. Also, NaOH is frequently used within the desalination plant itself.

Consequently, producing NaOH from seawater reverse osmosis (SWRO) brine for reuse within the SWRO facility has the potential to benefit environment and plant economics. By replacing NaOH manufactured off-site using chlor-alkali by an on-site, lower-energy process (e.g., one producing HCl as a byproduct instead of Cl2), the environmental and economic footprints of NaOH generation and transport are reduced. By diverting a portion of the brine discharge, less salt flows into the ocean, resulting in lower salt concentrations around brine discharge ports, which lessen the plant’s impact on marine life. Further, since both benefits scale with the amount of NaOH produced, any other nearby consumers of the NaOH produced would serve to increase the positive environmental and economic impacts of this technology.


In the following text, the authors point to the use of NaOH within a desalination plant, albeit in this case of a "SWRO" plant (Seawater Reverse Osmosis) plant.

They write:

Caustic soda has myriad uses both internal and external to the desalination plant. Internally, treating seawater feed with caustic soda increases the pH. At higher pH, several compounds are better rejected by the RO membrane. Around pH 9, the better-rejected borate anion B(OH)4– supplants boric acid as the dominant aqueous boron species.(11) The dissolved silica system behaves similarly, with the dominant SiO(OH)3– and SiO2(OH)22– species above pH 9 yielding better silica rejection,(12) and above pH 8, dissolved inorganic carbon exists as bicarbonate and free carbonate, which are better rejected than aqueous carbon dioxide.(13) Evidence also shows reduced organic fouling at high pH.(14) Finally, caustic soda is an ingredient in cleaning solutions to remove organic, biological, and organic/inorganic colloidal foulants and silica scale.(15)

For internal reuse, caustic soda purity requirements are moderate. Membrane manufacturers manuals for reverse osmosis(16) rate technical grade as sufficient purity for membrane and system compatibility.


I should point out at this point that while this situation applies to SWRO plants, NaOH would be useful in brine resulting from other processes. In particular it might prove of great utility in the recovery of certain metals from seawater, notably magnesium and calcium (but also including others) and another constituent of prime importance which is much more concentrated in seawater than it is in the atmosphere, carbon dioxide, along with certain carbon compounds. This would, however, probably involve a huge scale up of NaOH production, although there are some very cool approaches to in situ partitioning of seawater into HCl and NaOH fractions which I have no time to discuss here.

The authors further discuss the economic importance and current production methods for the production of sodium hydroxide:

n addition to its use in controlling pH and neutralizing acids, caustic soda is used as a reagent in the production of many chemicals. About 59% of NaOH in the EU and North America is used in the pulp and paper, inorganic, and organic chemical industries.(19) Soaps and detergent manufacture also account for significant demand. For external reuse, quality requirements are application specific, and some commercially produced caustic soda is of insufficient purity for certain industries. For example, caustic soda produced using the diaphragm process is not suitable for manufacturing viscose, also known as rayon.(20, 21)

Industrial production of caustic soda is massive. Global manufacture exceeded 59 million tons in 2004,(19) with significant growth in demand and capacity expected in Asia.(20) Production is also scalable, with plant capacities ranging from about 4.4 kt/yr (Kapachim, Inofita Viotias, Greece) to 1744 kt/yr (Dow, Stade, Germany) in the EU(22) and about 2 to 3333 kt/yr (Olin, Freeport, TX) in the US(20, 23) on a dry basis. [Estimated from chlorine capacity at 1.1 kt NaOH/kt chlorine,(18) which is slightly less than stoichiometric.] On the small end, ThyssenKrupp Uhde GmbH offers standardized skid-mounted plants at up to 17 kt/yr, and AVS Technology AG offers plants as small as 1.1 t/d.

About 99.5% of global caustic soda production is by the chlor-alkali process.(24) Briefly, the process produces caustic soda and chlorine gas in equimolar amounts by electrolysis of aqueous sodium chloride. Direct synthesis of process products can also produce hydrochloric acid, though less than 10% of HCl is manufactured this way.(25) (Technical aspects of the chlor-alkali process and other methods are discussed in-depth below.) Three variants of the process exist in widespread commercial use, generally distinguished by how catholyte and anolyte are separated. The variants are known as the membrane, diaphragm, and mercury processes.


The authors then discuss that the chlor-alkali process produces equal molar amounts of chlorine gas and NaOH and that the demand for these two commodities is not always matched, even if some of the chlorine is diverted to make another commodity, HCl, hydrochloric acid. (Hydrochloric acid is often a waste product needing disposal. There are huge waste disposal issues with it, and one dubious approach to dealing with it has been deep welling it.)

This mismatch has lead to wide fluctuations in the price of NaOH, as a graph from the paper shows:



It is worth noting that the "mercury process" - which is happily being phased out - has resulted in a large contribution to the widespread contamination of the environment with mercury. Although the amount of mercury from this source is definitely dwarfed by mercury contamination deriving from coal exhaust, fly ash and ash, it is still significant.

(Sometimes I think the whole world is developing "mad hatter disease." How else can we account for the placement of incredible fools like the orange nightmare in the White House, and his foreign equivalents, Kim Jung Un, Rodrigo Duarte, Recip Erdoğan, to name just a few.)

The authors graphically show the current chlor-alkali processes industrially in use:



The rest of the article is involved with thermodynamic and the always related economic issues, along with some technical arguments connected with membrane technology (which is the focus of the paper.)

Also discussed is heat, which is also an issue in the reduced pressure schemes about which I often privately muse.

Overall, I like these kinds of papers and I thought I'd share this one for anyone who may find it interesting. Interested readers who can manage access, are invited to look the paper up.

Esoteric I know, but important.

Enjoy the coming work week.


Substitution of Glycerol for Methanol For Denitrifying Sewage Sludge.

One of the real big environmental problems which gets less attention than maybe it used to, is involved with nitrogen chemistry.

In my view the most serious environmental impact may be the accumulation of nitrous oxide in the atmosphere, but the issue has very, very, very serious implications for both fresh and saline bodies of water.

Fixed nitrogen, along with phosphorous, was responsible for one of the most famous events related to the environmental impact of fixed nitrogen nutrients, the 2014 toxic algae bloom that shut the water supply to Toledo, Ohio because the particular species of algae produced a very potent biological toxic cyclic peptide, microcystin:



These outbreaks are now known all over the world. They are largely involved with agricultural practices.

Even where the output does not contain directly toxic compounds, these blooms can and do destroy major ecosystems. The "renewable" energy scheme to add ethanol to motor fuels, for example, has completely destroyed the ecosystem of the Mississippi Delta, because of nutrient run-off both nitrogen and phosphorous.

Although agriculture is a major cause, another is the treatment of sewage sludge.

In some, perhaps not enough, sewage plants, denitrification is accomplished using methanol as a carbon source. Although methanol can be made either by the hydrogenation of carbon dioxide or carbon monoxide, the source for the industrial quantities of all three of these starting materials is currently dangerous natural gas.

The waste product of this dangerous natural gas is directly dumped, without reserve directly into the planetary atmosphere, which it is destroying.

I'm generally an opponent of all forms of so called "renewable energy" at this point in my life, having decided in the last decade that they will never be as safe, as clean nor as reliable as nuclear energy, but a caveat is to note that one thing that living systems do better than nuclear energy will ever do is to collect carbon dioxide from the atmosphere, because biological systems, being self replicating, can cover huge amounts of surface area at almost no cost.

Algae, both deliberately grown and grown in uncontrolled conditions (such as occurred in Lake Erie) has often been studied as a source of fats, esters of fatty acids and the triol glycerol, which can be used to make biodiesel, a decent substitute for petroleum diesel, at least with some modifications.

The side product of biodiesel production is glycerol which is generally dumped as a waste product, not because it's entirely useless, but because there is much more produced by the biodiesel and soap industries than can be profitably utilized.

So I came across an old paper in my files that offered an interesting potential use for glycerol, which is to substitute for methanol as a carbon source in the denitrification of sewage sludge.

The paper is here:

Diagnosis and Quantification of Glycerol Assimilating Denitrifying Bacteria in an Integrated Fixed-Film Activated Sludge Reactor via 13C DNA Stable-Isotope Probing (Chandran and Lu, Environ. Sci. Technol., 2010, 44 (23), pp 8943–8949)

Some excerpts from the text, first the introduction, which I rehashed briefly above:

Methanol is one of the most widely used external organic carbon sources for enhancing denitrification at wastewater treatment plants (1-3). Of late, glycerol has emerged as an alternative to methanol due to three factors. First, the price of methanol, which is tied to the natural gas price, has been increasing (4). Second, the dramatic increase in biodiesel production as a means of moving away from petroleum as an energy source has given rise to significant quantities of glycerol as a waste product (5). Third, glycerol has been previouslyshownto foster higher denitrification kinetics than those of methanol (6, 7). Consequently, wastewater treatment plants today are intently considering glycerol as a supplement or replacement for methanol.

From the perspective of wastewater treatment process design, it is essential to determine the fraction of activated sludge bacteria assimilating any given carbon source...


Bacteria were isolated from sewage sludge treatment plants and then placed in a growth medium that was spiked with glycerol labeled with the heavy stable isotope of carbon, C-13.

They then looked for the fate of C-13 and noted the following:

The 13CDNAsequences of the biofilm samples were more diverse and dominated by Comamonasbadia(5/21),Bradyrhizobium sp. 1 (4/21), and Tessaracoccus bendigoensis (4/21) related bacteria. Bradyrhizobia and Tessaracocci belong to the family of Rhizobiales in R-proteobacteria (35) and Propionibacteriaceae in Actinobacteria (36), respectively. Very little is known about the denitrification capability of these bacteria and or their ability to use glycerol as an electron donor. It is notable that the glycerol assimilating bacteria diagnosed and quantified in this study have not been implicated in glycerol metabolism before (as reviewed by ref 5). A possible explanation for this discrepancy is that the previous studies selected their strains a priori for examining glycerol metabolism.


They find that the presence and distribution of organisms in denitrifying biofilms utilizing glycerol are considerably different than those in methanolic systems, and that the glycerol based systems seem to function better.

There's a lot of cool molecular biology in this paper, much of which is not really my bailiwick, but it's worth perusing just for general knowledge.

I personally feel that linear saturated and unsaturated fatty acids and products made by chemically modifying them might well be important tools in a putative post-petroleum age, should we ever have one before petroleum waste, along with coal and gas waste kills us. Since glycerol is a necessary byproduct of access to such materials of biological origin - ideally from microorganisms utilized in phosphorous and nitrogen contaminated waste waters - this interesting approach to denitrification seems quite interesting.

I'm not sure how much came of it - the paper is seven years old - but it's worth keeping in the back of one's mind.

I wish you a pleasant Sunday.



Now, THIS is a very cool Ph.D thesis: Francesco Ricci and the origins of chirality.

Life is asymmetric, and why this is so is one of the greatest mysteries of the universe. By asymmetric we are referring to the property that your hands have, they are mirror images of one another, but cannot be superimposed upon one another.

We refer to this property as chirality.

Here is a picture of the two forms of the simple amino acid alanine, with, by convention, the black wedge being representative of coming out of the plane of the page, the dashed wedge representative of being representative of going back behind the plane of the page:



In the laboratory, one can easily make alanine by the hydrogenation, in the presence of ammonia of the symmetric molecule pyruvic acid, with, say for example, a nickel or platinum catalyst. When one does this however, one will get a 50:50 mixture (exactly) of the two molecules above. We refer to such a 50:50 mixture as "racemic."

In living systems, by contrast, which also synthesize alanine from pyruvic acid, one will only get one of these isomers, the S isomer, 100%, exactly.

In fact, one can only synthesize pure chiral molecules in the laboratory (and this has been a subject of vast amounts of research over the last century or so) if one conducts the reaction in the presence of molecules that are also chiral. This is, in fact, what happens in living systems; the vast majority of molecules in living things (other than water) are chiral. But where did it come from? What was the first chiral molecule to exist in the absence of its mirror image, which we call its "enantiomer?"

I have wondered about this a lot while daydreaming over several decades; I've generally assumed with a vague sense, that it somehow resulted from certain types of chiral radiation associated with nuclear decay in cataclysmic stellar events. (Yes, light can be, and often is, chiral.) Here and there, I've pulled some papers down, but none were very satisfactory.

Today, while going through files I collected but never actually read, I came across a recent Ph.D. thesis at Princeton University, written by a young scientist named Francesco Ricci. It's entitled "Theoretical and Computational Studies of Condensed-Phase Phenomena: The Origin of Biological Homochirality, and the Liquid-Liquid Phase Transition in Network-Forming Fluids."

The thesis can be accessed here: Ricci, Ph.D Thesis, Princeton

Very early in the text I came across a concept of which I'd never ever heard, "Viedma ripening" involving homochiral molecules.

Viedma ripening...

Never heard of it.

It doesn't get any better than this, being old and fairly broadly exposed and then run across something from some very charming young guy talking about something about which you know nothing.

I'm going to be pulling up this kid's papers and his references in the next several weeks. Beautiful, very, very, beautiful.

It's going to be a fun Christmas break!

The Remarkable Thermal Stability of the MAX Phase Zr2Al4C5

There are many thermochemical cycles known for the decomposition of water into hydrogen and oxygen (in separate compartments) as well as thermochemical cycles for the decomposition of carbon dioxide into carbon monoxide and oxygen, again in separate compartments.

Carbon monoxide can also be disproportionated to give elemental carbon and carbon dioxide; this is known as the Bouardard reaction. Thus it is theoretically possible given a source of high temperatures to reverse coal combustion.

Carbon monoxide can - and industrially is - used to make hydrogen: This is known as the "water gas reaction:" CO + H2O <-> H2 + CO2. Industrially this important reaction, which is used to make 99% of the hydrogen on earth, is driven by the partial combustion of dangerous natural gas, a fuel that like oil and coal is destroying the planetary atmosphere.

However, if carbon monoxide were made instead from carbon dioxide of course, this would have possibly the effect of reversing the effects of combustion dangerous fossil fuels and directly dumping dangerous fossil fuel waste, chiefly (but not limited to) carbon dioxide.

These cycles have been broadly studied and are fairly well known.

Examples of thermochemical water splitting cycles are the "sulfur iodine" cycle, the UT-3 (CaBr2) cycle, the copper chloride cycle, and others.

Examples of thermochemical carbon dioxide splitting cycles are the tin oxide carbon dioxide and water splitting cycle, the cerium dioxide carbon dioxide splitting cycle, and one of my absolute favorites, the zinc oxide cycle, among others.

In order to get grants one must appeal to the useless fantasy about solar energy, in particular thermal solar energy plants, which have not worked, are not working and will not work, which is why in some cases they are described as "solar thermochemical cycles" but there is no practical reason that they would not work with cleaner, safer, and more practical and sustainable energy, nuclear energy.

The basic problem with many of these cycles - most of these cycles - is that they require fairly high temperatures in corrosive environments. The most famous of these cycles, the sulfur iodine cycle involves the thermal decomposition of two strong acids, sulfuric acid into sulfur dioxide, oxygen and water and the thermal splitting of hydroiodic acid, HI, into hydrogen and elemental iodine.

This is a serious materials science problem.

The extremely important reason that it would be worth solving this materials science problem is that the use of such cycles, coupled with heat transfer to thermoelectric devices or brayton/rankine combined cycle devices, would be extremely efficient overall. In general the greater the heat difference involved in a thermal process, the more work or exergy can be derived from it.

It is regrettable that research into high temperature refractory materials in many materials science departments that I toured with my son while we were researching universities for him to attend seems to have been deprioritized with the major aerospace problems having been more or less solved, but that said, there is yet still some that is of interest.

Egyptian-American scientist, Michel Barsoum at Drexel University has been a world leader in the development of the MAX phases (My son actually met him during one of the tours; he was admitted there but chose to go elsewhere.)

There are many different MAX phases, and I came across an interesting one that I encountered in a paper I came across tonight in my unexplored files is the one described in the title of this post, Zr2Al4C5 a ternary compound of the elements zirconium, aluminum, and carbon, all earth abundant elements. (Zirconium is also a prominent fission product.) The paper is this one:

Thermal stability of bulk Zr2Al4C5 ceramic at elevated temperatures (Zhang et al, Int. Journal of Refractory Metals and Hard Materials 30 (2012) 102–106)

The authors succinctly and accurately describe what the MAX phases are and why they are interesting:

MAX phases are nano layered ceramics with the general formula MAX, where M is an early transition metal, A is a Group A element, and X is either carbon or nitrogen. These materials exhibit a unique combination of the characteristics of both ceramics and metals [1–4]. The domain of layered ternary transition-metal carbide extends beyond the MAX phases to a new family...


They go on to describe a relatively new class of these compounds which are, again, ternary composites of zirconium (or its cogener hafnium) aluminum and carbon.

Here is what they say about the compound described in the title:

Among these compounds, Zr2Al4C5 ceramics exhibit perfect high-temperature mechanical properties. Young's modulus decreases slowly with increasing temperature. At 1580 °C, Young's modulus is 293 GPa, which is approximately 81% of that at room temperature. Simultaneously, the strength at 1400 °C is 371 MPa, which is approximately 10% higher than that at room temperature [9,10]. Zr/Hf–Al–C compounds demonstrate excellent elastic stiffness and strengths of up to the temperature range for ultrahigh-temperature applications.


Wow.

The research in this paper involves finding out how high temperatures can go before the MAX phase decomposes. (The authors note that these temperatures, the decomposition temperature of the various MAX phases - there are a lot of them - vary with the conditions to which they are exposed; they differ in the presence of vacuums, under various gases, inert and otherwise, and other chemical environments.)

Here are what they find out and conclude.

The high-temperature thermal stability of Zr2Al4C5 under Ar atmosphere has been studied by thermal expansion analysis. The presented thermal expansion analysis result is in good agreement with the XRD and SEM results. Zr2Al4C5 was susceptible to decomposition at temperatures above 1900 °C through sublimation of high vapor pressure of Al, which resulted in the formation of a little amount of Al and Zr2Al3C5 on the surface layer. Ternary-phase Zr2Al4C5 and/or Zr3Al4C6 decomposed to ZrC and Al4C3 above 1900 °C due to weaker covalent bonds between ZrC slabs and Al4C3-type layers. Zr2Al3C5 further decomposed to ZrC1−x and Al4C3 at 2000 °C, and the amount of decomposing phase was found to slowly increase. The dissociation of Zr2Al4C5 was not complete at the end of the experiment, implying that the process never reached completion because of very slow kinetics. The present study clearly indicates that thermal expansion analysis, when combined with XRD and SEM, can provide a practical way for studying the thermal stability of ultra-high temperature materials.


High temperature refractory materials can often be protected beyond their melting (or in this case decomposition) point by coating with thermal barrier coatings, the most widely used one being zirconium oxide. To the extent that this type of coating would be useful in extreme environments is questionable. It would certainly not be stable in the presence of decomposing sulfuric acid or hydroiodic acid, but it would be interesting to understand the stability of the MAX phase or modified version in question under these conditions.

It is interesting to note that zirconium, aluminum, and carbon are all fairly transparent to neutrons, and the stability of MAX phases in neutron fluxes is an active area of research. I personally believe that these phases might do remarkable things, should the world survive puerile orange fools and his traitorous apologists and fellow nut cases.

This is esoteric, I know, but interesting.

Self Medication by Orangatans Using Bioactive Plants.

The following paper is in Nature's open sourced journal Scientific Reports: Self-medication by orang-utans (Pongo pygmaeus) using bioactive properties of Dracaena cantleyi (I. Foitová et al, Scientific Reports 7, Article number: 16653 (2017))

This apparently is not the first instance among primates of this type of behavior, but it is only one of two examples of such a behavior of apes not originating in Africa. (As we originated in Africa, our particular species of ape does not qualify.)

According to this paper, orangatans have been observed to process (by chewing) this plant and then rubbing the resulting lather on their fur. Biological assays of the pulp of the plant showed, using cellular assays, that the plant had pronounced anti-inflammatory properties.

The paper is, again, open sourced, so there is no reason to excerpt it.

It's interesting, especially for the description of other species that self medicate.

Fascinating, I think.

Have a nice Friday tomorrow.

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