AJKOER
Radically Dubious
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Corrosion Chemistry of CaCl2 and MgCl2 Fully Explained?
So why are both MgCl2 and CaCl2 cited as particularly more corrosive to metals than sodium chloride?
Here is some documentation of this assertion. First, “CORROSION EFFECTS OF MAGNESIUM CHLORIDE AND SODIUM CHLORIDE ON AUTOMOBILE COMPONENTS” at https://trid.trb.org/view/642605 and “THE GROWING CASE AGAINST MAGNESIUM CHLORIDE” at https://eco-solutions.net/the-growing-case-against-magnesium... . The last article notes to quote:
“... hydroscopic chlorides (e.g., magnesium chloride and calcium chloride). The hydroscopic chlorides are more corrosive because deposits remain
moist and allow corrosion to occur for a much longer period. It has been demonstrated that when acid rain is present, there is a synergistic effect
(increase in corrosion rate) with chloride salts (200).”
and interestingly makes a comment that highlights the role of the Magnesium ion particularly, to quote:
"According to this model, magnesium from any source, either from reacting dolomite or from magnesium road deicers, has a major role in highway
concrete deterioration. "
Also importantly, the magnitude of increased corrosion, per this source https://www.lehigh.edu/~inenr/research/PDF/water-nexus-2.pdf , to quote:
"Although, CaCl2 · 6H2O is a suitable PCM from a thermal, cost, and safety standpoint, because it is a chloride-based salt, it is known to be highly
corrosive."
Also, this paper https://www.tandfonline.com/doi/pdf/10.1080/1478422X.2017.13... suggests more complex pathways could be present, to quote:
"...Na2HPO4 significantly decreased the corrosion rate. According to polarisation and XPS analyses, it is evident that the obtained low corrosion
rates on mild steel are related to the suppressed cathodic and anodic reactions and the formation of a protective film containing Fe, P, O, Ca or Mg."
So, complexing associated with chloride, together with hydroscopic properties resulting in near aqueous conditions, that result in formed more acidic
aqua complexes, appears to be the current understanding. But is this explanation for the highly corrosive nature for these particular select salts
possibly incomplete?
I would like to propose some more advanced chemistry, that is unique to the salts of calcium and magnesium. Namely, the associated formation (also
known to occur with aluminum, and calcium/magnesium ions) of the so-called semi-reduced complex consisting of a metal ion of Al, Mg or Ca that is
weakly attached to the superoxide radical anion (O2•−). The details of the chemistry and associated references can presented in this thread http://www.sciencemadness.org/talk/viewthread.php?tid=151828... . The source is "Oxidative Stress Gated by Fenton and Haber Weiss Reactions and
Its Association with Alzheimer’s Disease’:by Tushar Kanti Das, et al, published in Archives of Neuroscience, July 2014 2(3): e20078, DOI:
10.5812/archneurosci.20078, where the authors cite, in Figure 4, “ Formation of Aluminum Superoxide Semi reduced Radical Ion and Aluminum Superoxide
Complex (43)”.
In the current corrosion explanation context, the latter superoxide radical here could be formed from the interaction of a solvated electron
(emanating from the galvanic corrosion of the metal or alloy present or via say noble deposited carbon from incomplete fuel ignition) with oxygen/air,
namely:
O2 + e- (aq) = O2•−
especially at the air/moist surface interfaces occurring in humid conditions.
The advanced chemistry detailed previously incorporates the superoxide radical anion, which is now suspected to be augmented via an unstable compound
(namely, the semi-reduced complex with superoxide), that is transported and eventually breaks down liberating the original superoxide. This likely
results in an increased range of activity along with an extended life span of the underlying superoxide radical.
Speculatively, this argument could also extends an explanation of an associated disease element alluded in work, also for Aluminum ions resulting in
an oxidative stress disorder, potentially in the human brain. Further, the interaction of O2•− with HOCl (= O2 + •OH + Cl-) may even explain the
reported hyper-sensitivity of calcium hypochlorite and magnesium hypochlorite to air contact (see my comments and references here http://www.sciencemadness.org/talk/viewthread.php?tid=155249... ).
Now, in the current case of reported accelerated corrosion associated with CaCl2 and MgCl2, it is suggested that formed O2•− could then feed a
REDOX reaction system as, for example, was detailed in this work "Generation of Hydroxyl Radicals from Dissolved Transition Metals in Surrogate Lung
Fluid Solutions" by Edgar Vidrio at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2626252/ . Also, relatedly, see this work " Fe(II) oxidation by molecular O2 during HCl extraction"
here https://www.researchgate.net/publication/263026567_FeII_oxid... .
The net result is increased radical activity leading to more radical based dissolution especially in natural light (suggestively resulting from a more
powerful photo-redox system).
Is this added more advanced radical chemistry argument possible here?
[Edited on 9-3-2022 by AJKOER]
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Fantasma4500
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so theyre saying, its an superoxide that forms with help from aluminium? and that this ties into alzheimers being tied to aluminium toxicity.
its known by people who electroplate that copperplating a piece of steel will not inhibit it from rusting- supposedly even if its a "perfect" copper
strike plating, because there will always be some tiny pore hole and in that porehole the copper will inevitably catalyse the corrosion of the steel
through- supposedly Cu2O or CuO- CuO probably not since thats usually only formed at high temperature? i have found that some anti corrosion products
contain copper, copper grease- but its also loaded with sulfurized oil, but once the sulfur in that wears off it should infact really speed up the
corrosion
i always had the assumption that the chlorides simply worked to give chlorine atoms and that ended up attacking the steel- and when the hygroscopic
nature of CaCl2 or MgCl2 ends up on a steel surface and the hydrate has gone as far as it can drying in open air that could lead to same effect as
molten NaOH- very high amount of ions, higher than a concentrated solution- but if its about ClO- then this hygroscopic mass may also be more
susceptible to producing ClO-? if ClO- really is whats up then maybe a high boiling ketone could be added to scavenge the ClO- or something similar in
controlled environment to prove/disprove of it?
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AJKOER
Radically Dubious
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An interesting article found here https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.33... on the role of superoxide in the human body may be informative, to quote:
"Despite being essential for most forms of life, the high content of O2 in the atmosphere means that oxidation reactions are common place in our
environment. Although our body uses O2 and oxidation reactions to good effect for generating energy and killing invaders, unwanted side reactions are
unavoidable [12]. Therefore, to support aerobic metabolism, mechanisms had to evolve for the biological control of generating energy and killing
invaders, unwanted side reactions are unavoidable [12]. Therefore, to support aerobic metabolism, mechanisms had to evolve for the biological control
of water (Figure 1), which produces the free radical O2- by the 1-electron reduction of molecular O2 as the first intermediate in this pathway. The
majority of O2 is reduced by the cytochrome oxidase complex, which prevents release of the reactive intermediates. However, the evolution of a variety
of superoxide dismutase (SOD) enzymes, catalase, and peroxidase to remove the reactive intermediates suggests that a significant proportion of O2 is
reduced by this route."
[Edited on 11-3-2022 by AJKOER]
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Tsjerk
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| Quote: | But is this explanation for the highly corrosive nature for these particular select salts possibly incomplete?
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Do you have any real evidence for this to be true, except for your own wild ramblings?
The "quality" of your posts is going down AJOEKER... This one I could sort of follow, your references are now just links to earlier ramblings which
makes the whole thing quite readable. It does make the (lack of) prove a bit more layered, but more clear to be honest.
I will leave you to it again, good luck contemplating those radical ideas!
[Edited on 11-3-2022 by Tsjerk]
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sauveurdumonde
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This post is so hard to follow. First you're talking about metal corrosion, then you're talking about O2- radicals in the body? What is the point
you're trying to make here? This seems like a lot of information thrown at me but no particular reason for saying it
"There is a shadow of a nation behind you, the hope of a people... yet it may not matter. The Divide still stands against us."
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Fantasma4500
International Hazard
Posts: 1677
Registered: 12-12-2012
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speaking of aluminium, fluoride aids formation of superoxides. aluminium and fluoride has a funny relationship
https://gyazo.com/19666c7c4545bfb013020e312bdac8d3
https://gyazo.com/3496ed0a8d696e89ee9662218dc157a3
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