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NNadir

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Current location: New Jersey
Member since: 2002
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Fragile

It appears that the subscript and superscript HTML codes are still not working.

These are useful in the science forums.

Just letting you know...

Figure 13. (a) The dimensionless figure of merit (zT) as a function of temperature for n-type Mg3.07Sb[sub]1.5[/sub]Bi[/sub]0.5–x[/sub]Se[sub]x[/sub]. (b) zT in n-type Mg[sub]3.07[/sub]Sb[sub]1.5[/sub]Bi[sub]0.48[/sub]Se[sub]0.02[/sub] and the comparison with the reported n-type Mg3Sb[sub]1.48[/sub]Bi[sub]0.48[/sub]Te[sub]0.04[/sub],(13) p-type Ag-doped Mg[sub]3[/sub]Sb[sub]2[/sub],(20) Mg3Sb[sub]2[/sub][/sub],(19) Mg[sub]3[/sub]Sb[sub]1.8Bi[SUB][sub]0.2[/sub],(22) and Mg[sub]3[/sub]Sb[sub]2[/sub].(22)

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Goodbye Pork Pie Hat.

The Unknown Dissident.

Ain't Nobody

The astounding cadmium intake associated with rice in Southern China.

Recently in this space, I reported on the development of an inexpensive test for cadmium contamination developed by Chinese scientists, noting that China has a very serious problem with the contamination of their rice crops with this dangerous heavy metal.

That post is here: Fast, accurate determination of cadmium contamination without expensive instrumentation.

I have been generally aware of the cadmium contamination of Chinese rice over the years because, in something of a gadfly role, I question the rote assumption that so called "renewable energy" is actually safe and sustainable - it is neither, nor is it in fact even "renewable" - and I believe that simply by saying the word "renewable" in connection with energy people tend to abandon critical thinking and in fact, stop giving a rat's ass about the consequences of wishful thinking, the kind of wishful thinking that kills people.

Uncritical belief in the cleanliness and sustainability of so called "renewable energy" is our creationism on the left.

(The planet in the last ten years squandered over a trillion dollars on solar energy - a fig leaf for the gas industry without which solar energy would be even more useless than it is - with the result that the degradation of the planetary atmosphere accelerated to unprecedented levels. The solar industry has not worked, is not working and will not work to prevent climate change or to save the lives of even a minute fraction of the seven million people who die each year from air pollution.)

Whatever.

Having stumbled on that paper in my regular reading, I decided to update my understanding of the cadmium situation in China by picking up some references in the paper I discussed in the original post, and I came across a paper today that was truly astounding.

The new paper is here: Assessment of dietary cadmium exposure: A cross-sectional study in rural areas of south China (Yang et al, Food Control Volume 62, April 2016, Pages 284-290)

The abstract and "highlights" available in the link are obvious even if one cannot access the paper directly: The Chinese in the most contaminated areas are accumulating 340 mg of cadmium over their lifetime. For reference this is 38% of the LD50 dose, an LD 50 dose being the dose at which half of the test animals experiencing this level will die immediately. The chronic effects of cadmium exposure include not only death, but debilitating organ failure.

In the text of the paper the authors note that some of the levels of cadmium exposure exceed contamination levels in those regions of Japan where cadmium exposure lead to the outbreak of "Itai-Itai" ("Pain-Pain" disease characterized by severe osteoporosis and renal failure and increase mortality. The "Itai-Itai" victims experienced contamination levels averaging 0.59 ug/g in their rice; the Chinese in the surveyed regions in this paper are eating rice with 0.64 ug/g.

The analytical method employed for measurement was state of the art, an Agilent 7700 ICP/MS utilizing microwave nitric acid digestion.

An estimate of the number of people likely to experience severe health consequences has been made in another paper, this one:
Applying Cadmium Relative Bioavailability to Assess Dietary Intake from Rice to Predict Cadmium Urinary Excretion in Nonsmokers (Li et al, Environ. Sci. Technol., 2017, 51 (12), pp 6756–6764)

I quote:

"Urinary Cd has been associated with increased diabetes, hypertension, and even cardiovascular disease mortality.4,5 The incidence of osteoporosis at 2.4% associated with chronic Cd exposure from a smelting-impacted area in southeast China has-been correlated with urinary Cd < 2.0 μg g−1 creatinine.41 Considering the high predicted urinary Cd concentration of 4.77 μg g−1 creatinine in Hunan province with 67 million population, ∼1.6 million population may be at risk of osteoporosis due to rice consumption based on the low incidence of 2.4%. These findings suggest that ingestion of rice can be a health risk for populations in China, especially in southern China. Increased attention should be paid on food safety where both Cd concentration and Cd−RBA are important. Furthermore, strategy should be developed to modulate dietary Cd exposure via decreasing Cd−RBA in rice."


RBA = Relative bioavailability.

Over the years, I've had the misfortune to listen to people claim - in complete ignorance - that so called "renewable energy" is safer than nuclear energy. This is nonsensical and is based entirely on selective attention. I recently had to listen the unpleasant and frankly insipid announcement that the collapse of a tunnel at the Hanford nuclear reservation - a weapons plant - "proved" that nuclear power was unsafe. The tunnel collapse killed or injured no one and yet it was international news.

One hears a lot about Fukushima radiation, even though the death toll thus far is zero from radiation; in the same event thousands of people were killed by, um, seawater. Yet rising seas are ignored, radiation scare mongering is an international pass time.

One never hears, by contrast, about the trichloromethylsilane explosion at a Mitsubishi plant, also in Japan, trichloromethylsilane being an intermediate for some types of solar cells. The explosion killed 5 people immediately, and severely injured 15 people. The trichlorosilane explosion was not international news. Nobody gave a rat's ass about it, just like no one gives a rat's ass about the thousands of fatal natural gas explosions over the years; natural gas being the fuel without which the entire so called "renewable energy" scam would collapse in a New York minute.

Risk inasmuch as it involves threat to human life is described by WHO as being measured in DALY, "Disability Adjusted Lost Years." In this sort of calculation, a person killed instantly counts more than a person who might develop cancer from exposure in thirty years.

But don't kid yourself; the thirty year exposure limit is not zero for the solar scam. Cadmium is a carcinogen as well as a systematic poison. It has no half life. It never goes away.

The solar industry is trivial; the nuclear industry is not. One wonders, should the solar industry soak up so many more tens of trillions of dollars useless to even approach 1/5 of what nuclear energy has produced year after year after year for nearly half a century using technology developed in the 1960's, what the "solar" death toll might be.

It will not be small:

The cadmium situation in China suggests that the death toll for this still trivial form of energy is already higher than all the deaths associated with Fukushima, Chernobyl, yada, yada, so on and so on. These deaths will not be erased because currently no one - other than scientists in China - gives a shit about them.

The unacceptable death toll from the solar industry - should anyone ever pay attention to how "safe" this "green" scam is - is nonetheless still small when compared with the 70 million people who die each decade from air pollution while some us, wait like Estragon waiting for Godot, for the so called "renewable energy" industry to actually do something. It hasn't, it isn't, it won't.

The worst risk of "renewable energy" is that it is ineffective, and thus allows the killing to go on.

Nevertheless, to the extent we "distribute" cadmium telluride and cadmium selenide solar cells in this country, we will have the same hell to pay as the Chinese are paying now as they mine this stuff so we can be "green." The payment will come due during the lives of our children and grandchildren and their children and grandchildren, the people we screwed by doing nothing about the environment at all other than make glib predictions about how wonderful their energy sources will be since we expect them to do what we no idea how to do ourselves, live in some fantasy "renewable" nirvana.

Enjoy the upcoming holiday weekend.

Energy efficient electrolytic recovery of chlorine from waste HCl.

Here's a nice paper I came across this afternoon on addressing a very serious industrial problem, what to do with waste HCl, hydrochloric acid: Sustainable Non-Noble Metal Bifunctional Catalyst for Oxygen-Depolarized Cathode and Cl2 Evolution in HCl Electrolysis (Tharamani C. Nagaiah et al, Chem. Mater., 2017, 29 (10), pp 4253–4264).

The authors state the problem very well in the introduction:

"Chlorine is a key building element for manufacturing important industrial chemicals and engineering materials,(1) such as polymers, resins, and elastomers. The requirement of chlorine has risen appreciably in the last few decades, because of its increased demand for the preparation of chlorine-free end materials, such as polyurethanes (PU) and polycarbonates (PC), which are produced using chlorine chemistry as well as chlorinated polymers (e.g., PVC). Generally, ca. 50%(1) of the Cl2 employed commercially ends up forming HCl and chloride salts as a byproduct during the course of their manufacturing, particularly those using phosgene and isocyanates as a carbonylating agent, which are key precursors for the production of PU and PC.

The increased production of excess HCl as a byproduct cannot be utilized effectively only by employing it in the production of PVC or for other small manufacturing industries. Moreover, many small-scale industries in India and other developing countries simply quench the produced HCl with lime. The option of neutralizing the excess HCl is inadmissible for obvious reasons. Therefore, an intelligent way of valorizing the HCl produced as a byproduct is the recycling strategy for its conversion into high-purity Cl2 in order to make the associated processes sustainable. Chlorine production at present is primarily based on HCl electrolysis, which is now a substantially imperative methodology that involves the generation of hydrogen at the cathode (E0 = 0.00 V) and chlorine at anode (E0 = 1.36 V) with an overall reaction potential of −1.36 V.(2, 3)"


The authors don't note this in their paper, but a very common approach to chlorine production over the years has been to utilize mercury electrodes, which has lead to a very serious mercury contamination problem - commercial laundry bleach can often contain mercury - which along with medical waste and the worst environmental mercury release scheme of all, the use of dangerous fossil fuels as a source of energy, has contributed to serious mercury contamination of human beings.

(I sometimes speculate whether "mad hatter disease" is partially responsible for the willingness of a major North American country allowing itself to be "lead" by an inane and possibly insane corrupt orange monster of extremely low intelligence.)

In any case, they point out that one approach to regenerating chlorine is to oxidize it with oxygen with what is known as "an oxygen-consuming cathode known as oxygen depolarized cathode (ODC)" Here the oxygen gas is reduced to water with the addition of 4 protons and the release of 4 electrons, and at the anode, 4 chloride ions are oxidized to chlorine gas.

Unfortunately most of the ODC's contain expensive noble metals like platinum or rhodium. The authors exploit some very modern materials science to construct a new kind of ODC based on oxidized carbon nanotubes, zinc and tungsten.

Here's a picture of the structure of the catalyst:



The structure is a layered arrangement of polyvinyl imidazolium cationic polymers, oxidized carbon nanotubes and a zinc polyoxo tungstenate.

They claim that besides avoiding expensive metal catalysts (often not available in the third world as they describe) the approach saves about 30% of the energy required to regenerate chlorine from HCl using this system.

The disposal of HCl is a big problem in the first world as well. In many places HCl has been "deep welled" - that is dumped into deep bore holes.

This is hardly acceptable and if scalable, this is a very cool solution to the problem.

This is an obscure, but nonetheless important issue.

Have a nice Sunday evening.

Neil Bartlett's superpowerful oxidants NiF6- and AgF4- and the preparation of RhF6.

In recent years I've been interested in the inorganic room temperature molten salt formed by cesium fluoride and hydrogen fluoride, in which liquid is formed with a ratio (at the eutectic point) in a ratio of 2.3 molecules of HF to one molecule of CsF.

Generally fluorine gas, an important industrial agent for a variety of reasons, is formed by electrolysis of a related system in which potassium fluoride KF, complexes similarly with HF. However this system requires significant heat to melt, thus raising the energy cost associated with the preparation of F[sub]2[/sub] gas.

This is discussed in a nice paper in the Journal of Fluorine Chemistry published in 2006: Cesium fluorohydrogenate, Cs(FH)2.3F (Journal of Fluorine Chemistry Volume 127, Issue 10, October 2006, Pages 1339-1343)

In the introduction the authors write:

"1. Introduction

It has been known that alkaline metal fluorides (MF, M = alkaline metal) form complex salts with HF [1,2]. These salts are composed of M+ cations and fluorohydrogenate ((FH)nF−, where n is an integer) anions. KF–HF system is used as an electrolyte for electrochemical synthesis of elemental fluorine and many studies have been made on its physical, chemical and electrochemical properties [3–5]. A similar application was also examined for CsF–HF system, although it was not applied to industrial electrolysis due to the high cost of CsF [2,6]. The advantage of CsF–HF system is its low melting point compared to KF–HF system which enables the electrolysis to be performed at lower temperatures to save energy and give broader choice of materials of electrolytic cells. According to the phase diagram [2], the CsF–HF system has a eutectic point below room temperature at the composition of CsF:HF of 1 to 2.3 (m.p. 16.9 °C), corresponding to the formula, Cs(FH)[sub]2.3[/sub]F."


As I was poking around looking for this paper, I came across a paper by Neil Bartlett who is famous among chemists for his discovery, in 1962, that xenon, until then thought to be totally inert, could form compounds. Since 1962 many xenon compounds, most often fluorides but also oxides and other complex compounds, have been discovered, some by Bartlett himself.

The Barlett paper to which I refer, published just two years before his death in 2008 is this one:

Low temperature preparation and uses of potent oxidizers (Journal of Fluorine Chemistry Volume 127, Issue 10, October 2006, Pages 1285-1288)

Normally silver exhibits one oxidation state, 1+, although the 2+ state, analogous to that of its cogener copper, is well known.

Nickel's most common oxidation state is 2+, although a 3+ oxidation state is well known.

The Barlett chemistry is described in the graphic of his reactions found in the paper which may be seen by simply accessing the abstract. In this case, however, Barlett has prepared silver in the 3+ oxidation state, and nickel in the 4+ state, extremely unusual oxidation states.

These compounds, which are fluorine complexes are powerful oxidizing agents, and, as detailed in the paper, they are useful to prepare the hexafluorides of both rhodium and ruthenium (as well as platinum.)

Why is this important?

In less than 15 years the world supply of rhodium from ores, an important industrial catalyst and material with important technological implications, is expected be smaller than the supply available in used nuclear fuels. It is not clear that the element will be available from geological sources at economically recoverable levels at all in the next 20 to 50 years.

At that point it may become necessary to secure rhodium from used nuclear fuels, since that supply from ores will either have been depleted, or insufficient to meet demand for the metal.

Hexafluorides are known for 18 elements, and for all of them, the compounds are either gases or low boiling liquids. Historically used nuclear fuels have been recycled using complexes formed in solvents - the Purex process - which leaves a fair amount of chemical waste and other by products.

A far superior approach will be pyroprocessing including electrolytic recovery, perhaps in molten salts, including, but not limited to inorganic molten salts. (Organic room temperature molten salts - aka "ionic liquids" - are well know and vastly discussed compounds also of potential utility in the recovery of metals from complex mixtures like used nuclear fuels.)

Access to the hexafluorides of ruthenium and rhodium - both elements fairly large constituents of the fission products in used nuclear fuels - will allow for their recovery by simple distillation from the salts, a very clean process compared to extraction. In the case of rhodium in particular, although ruthenium is also an important and valuable element.

I note that uranium, neptunium, and plutonium, which are also valuable constituents of used nuclear fuels also form hexafluorides. The oxidation of americium to its highest state - AmF[sub]5[/sub] - also makes its separation from the lanthanide fission products and curium much easier to perform, although, regrettably, not as a gas.

Interesting and important implications I think, exciting chemistry to chemists of a certain type.

Have a nice Sunday afternoon.

A nice website put together by young engineers.

I love young engineers, the last best hope of humanity.

"About
This website was founded as a non-profit project, built entirely by a group of young engineers. Entire website is based on our own personal perspectives, and does not represent any views of any company in the energy industry.

Main purpose of this project is to help the public to learn some interesting and important information about the energy and about the nuclear energy. We realize that the basics in the nuclear physics do not belong to fundamental human knowledge and the term “nuclear” often evokes a feeling of something negative or even dangerous. We do not claim this or that opinion is the only opinion that is right. But it is noteworthy, that the vast majority of nuclear engineers, people who know what nuclear means, do not connect the term “nuclear” with anything negative or dangerous."


Nuclear Power for Everybody.

They have some very nice, nerdy quizzes.
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