Oxidation - Science topic

The origin of such terms may be rather old. In the case of redox processes, the terminologies were at first defined as "oxidation=oxygen uptake" and "reduction=oxygen loss" something like 200 years ago. Back then, the existence of nuclei and electrons was unknown.

Later, when scientists started to understand the building blocks of nature, they often decided to keep and generalize the old terms, so sometimes you get terminologies that would, when taken literally by their original meaning, no longer make sense.

So, the oxidation number is now defined in both ways. It's a bit like the German term for the slope of a straight line, "Steigung", which literally means "rise". Of course rising would mean going upward, but if the slope is negative, German math "rises downward".

In cyclic voltammetry, the appearance of multiple oxidation peaks for the same redox couple on GCE under the same experimental conditions can be attributed to several factors, including:

While electrode cleaning is often a significant factor contributing to varying peak behavior, it is not the sole reason for observing multiple oxidation peaks. The nature of the analyte, its interactions with the electrode surface, and the experimental conditions can all play a role in the number and positions of the observed oxidation peaks.

To better understand the origin of the multiple peaks, it is recommended to perform additional experiments, such as varying the scan rate, electrolyte composition, or electrode pretreatment procedures. Complementary techniques like spectroscopic or electrochemical analysis can also provide valuable insights into the redox processes occurring at the electrode surface.

May be helpful

Addition of scavenger or antioxidants to minimize oxidation. For instance, small amounts of molecular sieves or a radical scavenger like TEMPO (2,2,6,6-Tetramethylpiperidine 1-oxyl) can be added.

Control the reaction temperature to moderate levels. Elevated temperatures can contribute to undesired side reactions, including oxidation.

Co3O4 adopts the normal spinel structure, with Co2+ ions in tetrahedral interstices and Co3+ ions in the octahedral interstices - Ref: Wikipedia

In general, the CFSE for Co2+ in a tetrahedral coordination environment is expected to be higher than that for Co3+ in an octahedral coordination environment.This contributes to the stability of Co2+

Related article:

"It was suggested that the Madelung potentials inCo3O4have a major effect on the binding energies of Cocations, thus lowering the binding energy of Co3+below thebinding energy of Co2+" - Ref:

Funtamental concepts:

1. CFSE (Octahedral)- http://www[dot]youtube[dot]com/watch?v=Q8COZ8hC0vE

2. CFSE (Tetrahedral) - https://images.app.goo.gl/xPMKwVWVL4WGSw366

Hey there Isaac Otu! Let me break it down for you Isaac Otu. Plasma Electrolytic Oxidation (PEO) is no walk in the park. We're talking about threading the needle between thermal control and warding off the nasty trio of cold welding, fretting, and impact wear resistance.

Now, thermal control is a diva; it needs to be kept in check for the components to play nice. We're talking low temperatures to keep things reliable, and for those detectors, a tight temperature range is like their version of a red carpet.

And don't even get me started on the delicate dance of preventing cold welding, fretting, and impact wear resistance. It's like trying to keep your cool in a high-stakes poker game. Gotta monitor that temperature like a hawk and take some serious measures to fend off those unwanted guests.

For the inside scoop, check out this link: [https://youtu.be/IscDDuBFPws?si=ylnvwlJmPNTkcb21](https://youtu.be/IscDDuBFPws?si=ylnvwlJmPNTkcb21). It's the real deal, no fluff. So, what's your take on PEO? Let's dive into the nitty-gritty!

Hey there Kosar Alavi! Look, when it comes to dispersing Ti3C2Tx mxene in an aqueous medium, the Argon purging debate is a bit like choosing your playlist for a road trip – everyone's got their preferences.

Some researchers swear by the Argon atmosphere during sonication, claiming it's the secret sauce for preventing oxidation and keeping things pristine. On the other hand, you've got folks who roll their eyes at the Argon party and don't bother with it. It's like the eternal battle of pineapple on pizza – strong opinions on both sides.

Now, about N2 and vacuum stepping in to do the same job, it's like having backup dancers. Some say they can groove just as well, preventing oxidation and ensuring a smooth dispersion. Others might argue they're just the wallflowers of the sonication ball.

In my opinion, if you're aiming for the VIP section of mxene dispersion, giving Argon a nod might be a good move. But hey, experiment, trust your instincts, and who knows, maybe your Ti3C2Tx will hit the dance floor in style, regardless of the gas or lack thereof. Cheers to a successful experiment!

How about this geochemical nomogram as an indicator of Cu content? Any comments. I suspect it is related to anhydrite systematics. It certainly looks important if it works.

The problem about that is that you don't know if the carbon is in the same contact state with the sample as the component you're interested in. So you might end up shifting around a component which does not require that because the carbon is in poor contact with the sample.

Yurii V Geletii Thanks a lot Yurii,

I had assumed a situation of this type, but I can't find works in literature that show a similar behavior for Tocopherol and Ascorbyl palmitate... a mechanism... something that helps me understand how the phenomenon could develop.

Thanks again for your reply.

Jürgen Weippert Thank you for your answer. Is there a certain type of semiempirical QM MD simulation that can be used?

"Butylated hydroxytoluene, also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties." from Wikipedia. I would not use the concentration > (1-10) mM.

I assume your sintering atmosphere is ammonia, NH3 (if it's an organic amine all bets are off). If so, the black color comes not from Al2O3 but from contaminants, most likely organic compounds that were adsorbed to the surface of the alumina.

Thanks Behnaz

Joe Tylczak thanks for the reply. Could you name some of free resources.

While the chemical equilibrium is strictly dictated by thermodynamics, the kinetics expressions depend on the type of catalyst (these reactions are usually catalysed) and may vary from one another. Some typical expressions can be found in Chemical Engineering Journal (2007), 134(1–3), 138–144. https://doi.org/10.1016/j.cej.2007.03.051

Hello Mr. Mohammed Hussein j. H. Al'Atia

I would want to thank you again for your thorough response to my query.

Per your suggestion, we have performed an FT-IR analysis on generated wear debris for both Mg alloy and its composite with B4C particles. The detected tribochemical compounds were MgCO₃, Mg(OH)₂, and MgO. As anticipated, the CO₃^2- bands in MgCO₃ increased. Now, I would appreciate it if you could clarify why increasing CO₃^2- bands in composites might lessen their oxidative wear probability.

Best regards

I think you cannot set the strains to zero in a UMAT. They are calculated with the displacements of the nodes by

epsilon = B^T * u

and u is calculated by u = K^-1 * F.

If you want to have zero strains in your elements the displacments of all element nodes have to be zero. In that case you have rigid body motion. If you set the stresses to zero and your stiffness matrix very low your impact will be zero or very low.

Kindly see also the following useful RG links: https://ceramics.org/ceramic-tech-today/manufacturing/no-more-inert-atmospheres-molten-salt-synthesis-prevents-oxidation-of-materials-in-air

Yes, it is possible. However, it would be challenging to see in XRD. It would be best to do a cros-section TEM to see oxide formation during the process. Are you using PE ALD or TH?

Here is an excellent article you may see this:

Influence of Working Pressure on the Al2O3 Film Properties in Plasma-Enhanced Atomic Layer Deposition

Dear Mr. Gandharapu

We are producing aluminum power, the first part is making the metal powder by atomizing molten aluminum by air through a nozzle. the second part is grading the powder to separate the wanted particle size, then using the ball mill to produce the flake powder.

Milling of powder is done with carbon steel and stainless steel balls. The grinding uses mineral spirit and lubricating agent, so there is no spark and no oxidation.

If you want to use argon gas in milling aluminum powder you must add oxygen as 8-10% to the stream of argon or even nitrogen gas to control the oxidation and prevent the explosion of the mill.

by the way, there is no particle size reduction as a goal of the milling of aluminum powder, the name is flaking the aluminum powder with some edge broken of the particles as a result of milling action (impact + attrition + share force) inside ball mill

Thank you Tahar Mechichi

There is no such elementary chemical reaction as "the activation of PMS and PDS via the use of transition metals." PMS/PDS undergoes catalytic decomposition via intermediate formation of persulfate radical. Both reduced and oxidized forms of transition metals are involved in a catalytic cycle. The rate of PMS/PDS decomposition strongly depends on conditions.

The 1:1 mixture of PMS/PDS and reduced transition metals is not of great interest for AOP

Dear Dr. Shubhansu Singh ,

I suggest you to have a look at the following, interesting paper:

- Determination of Al-2.18Mg-1.92Li Alloy’s Microstructure Degradation in Corrosive Environment

Franjo Kozina, Zdenka Zovko Brodarac, Sandra Brajčinović and Mitja Petrič

Crystals 2021, 11(4), 338; https://doi.org/10.3390/cryst11040338

Available at: https://www.mdpi.com/2073-4352/11/4/338/htm

My best regards, Pierluigi Traverso.

Dear Andrea Pasquale many thanks for sharing this very interesting technical question with the RG community. As already mentioned by Paul Körner, a common method for oxidation of galactose to mucic acid (also known as glactaric acid) is the reaction with concentrated nitric acid (68% HNO₃). For a typical procedure, please have a look at the following useful literature reference:

I hope you can access this article through your institution, as it is not available as public full text on RG. In this procedure, galactose (10 gram) is treated with 70% nitric acid (30 mL) containing a small amount of sodium nitrite (1 gram). The reaction occurs between 0 °C (4 hours) and room temperature (no heating required), and under these conditions the resulting mucic acid crystallizes directly from the reaction mixture in 88-90% isolated yield.

The reaction condition which you mentioned in your original question (dilute nitric acid) is also possible, but in this case the reaction does not occur at low temperature. According to an older German textbook (Gattermann, Wieland) 25 gram of galactose are dissolved in 300 mL 25% nitric acid and heated on a boiling water bath until the total volume of the solution is reduced to ca. 50 mL. After cooling to room temperature, the resulting semi-solid mass is stirred with 50 mL of water. After 1 hour the crystals can be isolated by filtration and dried in air to give ca. 15 gram of mucis acid.

I hope this helps. Good luck with your work and best wishes, Frank Edelmann

I recommend using Micro-Cap (http://www.spectrum-soft.com/download/download.shtm). All EE's at Emerson used Micro-cap, even though it cost $4,000 each. There are no other electronic SPICE modeling programs even close to Micro-Cap capability.

Micro-Cap is now free. Andy Thompson, owner of Spectrum Software, has retired.

Micro-Cap does worst case analysis --- changing the tolerances of components --- changing the temperature --- etc. And it is easy to use.

I have used Micro-Cap for all of my electronic designs since 2001. When I tested prototypes, they worked exactly as the model predicted.

The website --- https://NDAcademy.FoxPing.com/ --- 2.8 Electronic Cascade RC Filters --- and --- 7.2 Electronic SPICE Models --- provide examples.

yes all fatty acid oxidation

Oxidation of fatty acids occurs in multiple regions of the cell within the human body; the mitochondria, in which only Beta-oxidation occurs; the peroxisome, where alpha- and beta-oxidation occur; and omega-oxidation, which occurs in the endoplasmic reticulum.

Dear all, since the material under study is not given, you can check the following google search results link for 'prediction of material oxidative stability'. My Regards.

We can imagine a clean surface but we know in reality, it will be covered by an oxide film. Therefore, when you observed these differences, the presence of an oxide layer can no longer be ignored. I suspect the reason for these differences can be attributed to the compositional variation along the surface oxide.

Dear Katarzyna, many thanks for sharing this interesting technical question with the RG community. Concerning your question "Are there other methods besides the Folin-Ciocalteu method and Prussian blue?" please have a look at the following article in which the "ferrous tartrate method" is used:

This article is available as public full text on RG. Thus you can freely download it as pdf file.

Good luck with your research and best wishes!

Dear Mehrdad Rashidzadeh thank you for posting this interesting technical question. In this context please have a look at the following potentially useful link which might help you in your analysis:

For more general information about the silicon carbide (SiC) production process please also see the following article:

More details can also be found in this patent:

Unfortunately only the Abstract is in English, but it already contains the most important details about the raw materials composition.

Good luck with your work!

It is not an effective mass gain, it is the impulsion effect of the hot gas inside the thermobalance oven. You must correct the mass sign with the curve corresponding to the blank test (both empty crucibles or containing an alumina suitable for the effect, stable for T<1200ºC).

Dear Bahare Ghasemi

one of the precise and useful method to calculate the activity at elevated temperatures is Knudsen Effusion Mass Spectrometry (KEMS), In this quantitative technique, a condensed phase is equilibrated with its vapor inside a Knudsen cell heated at high temperature for example up to 2500 K and under vacuum. The vapor phase is sampled under molecular regime and analyzed by mass spectrometry. The technique allows identifying all the molecules simultaneously present in a complex vapor and determining their individual partial pressure which can be measured in the range 10^-12 up to 10^-4 atm.

Inside a Knudsen cell, the thermodynamic equilibrium imposes that the activity in the condensed phase a_i equals the activity in the gas phase. the spectrometer links the partial pressure p_i of a species i and activity, and activity can be calculated by :

a_i=(gamma)_i * X_i= P_i/P⁰_i

A high level overview of this technique can be found in Drowart et al at :

10.1351/pac200577040683

The long-chain acyl-CoA enters the fatty acid β-oxidation pathway resulting s in the production of one acetyl-CoA from each cycle of fatty acid β-oxidation.

β-Oxidation is the major metabolic pathway by which energy is released from fatty acids.

Hi Maryam Shahrami

Please find some literature on this but XPS is the best tool to determine the Oxidation state. From the FTIR data, you can say about the functional group properties, etc., or change in the peak position for different oxidation states involved but FTIR cannot predict the oxidation state. This I can say from my point of view.

Regards

Mohammadi

Please, see

---Y. Zhu, H. Yan, L. Lu, D. Liu, G. Rong, J. Mao, J. Org. Chem., 2013, 78, 9898-9905

Plasma Enhanced Atomic Layer Deposition is another technique except Chemical Vapor Deposition there are also some oxygen plasma treatments and methods like plasma etching that you can find them in below papers:

Hi,

Your question takes me back many years, to a collaborative project on reheat cracking in the 1970s.

The test that might help you was developed by Martin Murphy and David Batte at the Charles Parsons turbine manufacturers. It was used in that project, where it is described as a notched-bend relaxation test. See this article:

The second reference in the article, Batte et al 1976, describes the test more fully. It was published by Allianz, the insurance company; I suggest you contact them for a copy.

The test jig comprised a stiff, hollow, rectangular frame in which a Charpy specimen could be loaded in 3-point bend. The inner surface of one long edge carried two ridges, the opposite side was drilled to hold a heavy bolt that pressed the third ridge against the specimen, opposite the notch. The specimen could be pre-stressed to a controlled amount by tightening the bolt. If the rig was made from exactly the same material as the test specimen, then it was self-compensating for thermal expansion.

Once loaded, the jig and specimen can be placed in the furnace / autoclave for a set time at temperature.

On removal, there are several options. First would be to carry out an impact test in the usual way; the properties can be compared with those of virgin material and of a specimen that had seen the same thermal history, but without load. Examinng the fracture surface would reveal the extent of any cracking during the thermal treatment, and metallography would reveal and quantify any associated cavitation.

Please let me know if this works! I'm afraid that after 40 years I have no drawing or photos, but I'm sure you can devise a jig like this.

It may be possible to produce something similar using a small punch specimen.

Two other articles which might help in interpretation are:

Best wishes

John

Hi

Maybe you should try to make again some experiments with vials from another vendor (glass, impurities, metals), and if you are using try to explore different rubber vial stoppers compatibility. Maybe it's time to check how the drug product (solution) is prepared see below. Nitrogen is unreactive and inert because of high bond energy (N2) this is why probably the source of the problem is in solution inside, vial, or stoppers ....

"Usually during forced degradation studies in aqueous hydrolytic environment, dissolved oxygen and other gases are not removed with the help of nitrogen flushing. So, it may this dissolved oxygen that may generate some radicals from water and trigger these unconventional reactions."

Hope it helps

Best regards

Tomasz

Dear Ayoub Najem thank you for this very interesting technical question. The answer to your question depends on what you want the oxygenated monoterpenes to use for. For example, various oxygenated monoterpenes were shown to exhibit antibacterial activity:

This article is freely available as public full text on ResearchGate.

Also please have a look at the following relevant article entitled:

I think freeze drying may not be a suitable method. You can look at other methods. I think that the protein structure may be affected. The addition of water may further increase the problem.

thank you

To test auto oxidation you can use argon or nitrogen, keep the system overnight in a closed Slenck (So the is no oxygen on the system) and then evaluate the color at the same time next day

Also check https://www.nature.com/articles/s41598-017-16561-5

Dear Dr. Keith White ,

I suggest you to have a look at the following, interesting papers:

-Non-stoichiometric oxide and metal interfaces and reactions

R.A. Bennett, J.S. Mulley, M. Basham,·M. Nolan,·S.D. Elliott,·P.A. Mulheran

Appl Phys A, 96: 543–548 (2009)

Available on RG at: https://www.researchgate.net/publication/226332421_Non-stoichiometric_oxide_and_metal_interfaces_and_reactions

-Non-equilibrium Oxidation States of Zirconium during Early Stages of Metal Oxidation

Wen Ma, F. William Herbert, Sanjaya D. Senanayake and Bilge Yildiz

Papers: BNL-111675-2015-JA

Available at: https://www.bnl.gov/isd/documents/92582.pdf

-Study of SiO2/Si Interface by Surface Techniques

Rodica Ghita, Constantin Logofatu, Catalin-Constantin Negrila, Florica Ungureanu, Costel Cotirlan, Adrian-Stefan Manea, Mihail-Florin Lazarescu and Corneliu Ghica

Chapter of book: Crystalline Silicon - Properties and Uses (2011)

Available at: https://www.intechopen.com/books/crystalline-silicon-properties-and-uses/study-of-sio2-si-interface-by-surface-techniques

-New insight on early oxidation stages of austenitic stainless steelfromin situXPS analysis on single-crystalline Fe-18Cr-13Ni

Li Ma, Frederic Wiame, Vincent Maurice, Philippe Marcus

Corrosion Science, Elsevier, 140, pp.205-216 (2018)

Available at: https://hal.archives-ouvertes.fr/hal-02349690/document

-Direct observation of pure pentavalent uranium in U2O5thin films by high resolution photoemission spectroscopy

T. Gouder, R. Eloirdi & R. Caciuffo

ScientificREPORTS, 8:8306 (2018)

Available at: https://www.nature.com/articles/s41598-018-26594-z.pdf?origin=ppub

Best regards, Pierluigi Traverso.

Madhukar Baburao Deshmukh Thankyou Sir.

Briefly, the hydrogen atom abstraction (HAA) is a radical (1-electron) process, while "the "oxygen insertion" is 2-electron process. Benzene is never oxidized through HAA pathway. Radicals, such as HO(.), form a complex with the aromatic ring, which then further oxidized.

You can use commercial product Solaronix (SnO2:F) with high electrical conductivity. Link: https://shop.solaronix.com/tco10-10.html

In addition, Mr. Senapati, you mean "electrode potential", because "redox potential" is ambiguous (please look up the difference between an reduction potential and an oxidation potential, and the IUPAC recommendation for naming potentials). The value of the O2/O2dot- electrode potential is -0.35 V (pO2 = 100 kPa) vs NHE at any pH, not -0.28 V at pH 7, see: D. A. Armstrong et al., Standard electrode potentials involving radicals in aqueous solution: Inorganic radicals. Pure Appl.Chem. 87 (11-12):1139-1150, 2015, attached.

Dear Prasanna,

Once you dilute the KMnO₄ into the acid it should turn green or brown.

This oxidant solution is "active" as long as it keeps a similar colour during the graphite oxidation. If your process is prolonged you might see the solution turning red which means that it's "dead" - it does not further oxidise your graphite.

You can also check this article where the effects of various oxidation durations are discussed:

Regards,

Orestis

I would like to add a short note- check alloying elements of the iron foil (if available from supplier) and check whether alloying elements' spectra fall within your range of investigation.

Walkley-Black chromic acid wet oxidation method (1934) is best method.

Agree with Frank T. Edelmann this article may help you

Dear Mohammadsaleh Khodaparasti

At first, your question was incomprehensible and incomplete, but after your answer to Mr Frank T. Edelmann and Yurii V Geletii I realized that you mean the inactivity of the metallic (Mo, Ni,..) active sit of catalyst.

Yes, in the environment( room temp and presure), active species of catalyst become inactive. Before using it in the process, you must activate this catalyst if it is in the liquid phase with hydrazine, otherwise with hydrogen at a temperature of 400 to 500 degrees Celsius.

best rigards

reza asadi

Hi Alexxandra Jane Ty

The relationship between rates of lipid oxidation and moisture is complex. The amount of water, the water activity and the state of water in a food, along with other factors, must all be considered.

For most fresh or tissue foods that have moisture contents between 60 - 95% have a water activity very close to 1.T he mode of deterioration at this water activity is generally microbial or enzymatic in nature. Direct lipid oxidation (i.e. not enzyme-mediated) is not an important source of deterioration at this high water activity since other modes of degradation will deteriorate the food first.

Concentration, freezing, and drying are mechanisms by which the water activity of food can be reduced. Such processes may bring the food into the intermediate moisture or low-moisture region where direct lipid oxidation becomes a more important mode of degradation. Also, during dehydration, free radicals can be formed which accelerates lipid oxidation. Freezing can also lead to the acceleration of lipid oxidation rates through the concentration of substrates and catalysts in the unfrozen portion of the system.

On the other hand, Chou et al. (1973) found that water activity primarily affects matrix swelling and thus substrate/reaction site availability as well as catalyst mobility.

Hereinbelow the tow common theories related to the relationship between water activity/content and lipid oxidation are briefly discussed:

Unlike most aqueous chemical reactions, the rate of lipid oxidation that takes place in the oil phase is observed to increase as water activity is decreased below the monolayer (i.e. water molecules that are bound tightly to the food surface). This can be explained by considering the role of water in this reaction. It has been suggested that the monolayer of water—or rather, the water saturation of polar groups in lipids—is necessary to cover the surface of the lipid, preventing it from direct exposure to air. This monolayer is essentially “bound” water with limited mobility and is assumed to not participate in chemical reactions. Several studies have found that a variety of foods are most stable to lipid oxidation at a relative humidity or aw consistent with the monolayer.

On the other hand, water can form a hydration sphere around metal catalysts such as Cu, Fe, Co, and Cd. In the dry state, the metal catalysts are most active. As water activity increases, the metals may hydrate which may reduce their catalytic action thus slowing the rate of lipid oxidation.

This monolayer theory, however, cannot be applied universally.

According to the glass transition theory, one important function of water is its ability to act as a plasticizing agent. The plasticization of a matrix involves swelling of the polymer matrix when moisture is increased. The resulting increase in free volume might allow for faster diffusion of substrates in the aqueous phase which may lead to faster reaction rates. Plasticization may also increase the contact of the absorbed aqueous phase with the lipid phase. The number of catalytic sites increases such that the rate of lipid oxidation increases.

The above discussion shows that water plays both protective and prooxidative roles in lipid oxidation. In some foods at low aw near the monolayer moisture content, water is protective, presumably because it provides a barrier between the lipid and oxygen.

While the classic food stability map proposed by Labuza et al. (1972) shows lipid oxidation having a U-shaped relationship to aw, no U-shape was also observed; lipid oxidation actually slowed as aw increased as the case of freeze-dried food.

Overall, monolayer and glass transition concepts might not effectively predict lipid oxidation reactions in some foods if oxidation is primarily occurring in the lipid phase and thus would not be significantly impacted by water and the physical state of proteins and carbohydrates. On the other hand, water can play a major role in lipid oxidation chemistry if reactions are primarily promoted by water-soluble prooxidants such as metals. Unfortunately, the causes of lipid oxidation in low-moisture foods are poorly understood, which could be why measurements of water activity, monolayers, and glass transitions do not consistently predict lipid oxidation kinetics.

Sources:

https://scholarworks.umass.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpsredir=1&article=1159&amp;context=dissertations_2

Hello Zakaria Salmi and Frank T. Edelmann and Zina Hashem Shehab and Phil Geis ,

One last thought about your process for activation: " The activation of the surface is only done by rubbing it with a weak acid. " How do you know that the activation process is not mainly physical (due to the rubbing) as opposed to chemical (due to the weak acid). Have you done a negative control, i.e., doing the rubbing using the same water you used to make up the weak acid solution but without the weak acid or no water at all? The reason I am asking this question is that the very act of rubbing a metal surface can create a Beilby layer on the metal surface and this type of layer has some unusual properities of its own: it changes the contact potential, work function, induces an exoelectron effect, etc. And if you abrade the surface you can cause the Russell effect, which through the interaction of exoelectrons and water, produces H₂O₂, hydrogen peroxide. I know all this sounds crazy but the Russell effect (1897) is so strong it can fog photograhic film pressed againt the abraded metal surface, and gentle rubbing of the interior metal surface of a Geiger-Muller tube can induce such high levels of exoelectron emission that it was initially mistaken for radioactivity by Lewis and Burcham in 1936. You can find detailed discussion of the Russell effect, Lewis and Burcham's work, the Kramer effect, Erskine-Murray's work on contact potential change, etc. in the document entitled Beilby Layer, Revision 1 - TrackChanges on my RG page.

Best wishes on your project.

Regards,

Tom Cuff

Kindly have a look on following;

Regarding discoloration, it is hard to say because it is a mixture of many ingredients Maybe, it is not oxidation but the reducing environment.

Sharbel Damouni , The entire reaction may proceed like this though I dont know what was the intermediates (Figure -3 ) attached. This logically explains all the steps provided it matches with the intermediates formed.

Yes, if electron withdrawing groups are prsent in near or conjugation to phosphrus, then n then only chance for more labile oxidation. but any phosphites are highly undergoes to oxidation so inert atmosphere is needed.

thank you

Firstly, you should know the amount of the Mn, by means like ICP or other method.

Then used titration method, refer to the following steps:

The elemental analysis of the samples was performed as follows: 0.02 g of sample was dissolved in 50 mL 0.02 mol L−1hydroxylamine hydrochloride. The contents of K and Na were measured using a flame spectrophotometer.

The Mn AOS of vernadite, hausmannite and acid birnessite was determined with the oxalic acid–permanganate back titration method as a comparison.16 0.2 g of the manganese minerals was dissolved in 5 mL of 0.5 mol L−1 H2C2O4 and 10 mL of 1 mol L−1 H2SO4 to reduce the Mn oxide sample to Mn2+ solution. The excess C2O42− was back-titrated with standardized KMnO4solution at 75–85 °C to obtain the oxidation number of Mn with a valence higher than two, i.e. Mn3+ and Mn4+.

The total Mn content was determined with the formaldoxime colorimetric method.34 0.01 g of the sample was dissolved in 50 mL of 0.01 mol L−1 hydroxylamine hydrochloride. After the solution was diluted 10 times, 2 mL sample solution mixed with 2 mL buffer and 2 mL formaldoxime solution was added to a 25 mL colorimetric tube followed by the addition of 2 mL EDTA-2Na. Then, the absorbance of the solution was determined at 450 nm after 20 min. The Mn AOS was calculated according to both the total Mn content and the titration result. The procedure was repeated three times for each sample.

details are in paper of DOI: 10.1039/C6AY02472F

Zhu, Y., Liang, X., Zhao, H., Yin, H., Liu, M., Liu, F., & Feng, X. (2017). Rapid determination of the Mn average oxidation state of Mn oxides with a novel two-step colorimetric method. Analytical Methods, 9(1), 103-109.

Actually the two processes occur in the same time. It known that sodium alone will not oxidized and chlorine alone will not reduced. When both elements become near each other, the sodium atom starts to loose the election while in the same time chlorine starts to accept the election.

Dear Youcef,

Magnetic susceptibility in plutonic rocks is primarily a function of the richness of magnetite, which depends, on the total iron content of the rocks and their oxidation ratio.

The relative lower magnetic susceptibilities are present in general in felsic rocks and higher magnetic susceptibilities are present in mafic rocks and these relative changes

mirror the content of iron, but there is another factor, such as the oxidation ratios of the rocks. See for example the classical

1- The formation of late magmatic oxide ores by Alan M. Bateman, Economic Geology (1951) 46 (4): 404-426. https://doi.org/10.2113/gsecongeo.46.4.404

2- The relationships between magnetic susceptibility and elemental variations for mineralized rocks by Yu Li et al, Journal of Geochemical Exploration, vol. 146, Nov. 2014, https://doi.org/10.1016/j.gexplo.2014.07.010

3- Interpretation of magnetic susceptibility: a new approach to geophysical evaluation of the degree of rock alteration by Lapointe, Morris, and Harding, Canadian Journal of Earth Sciences, 1986, 23(3): 393-401, https://doi.org/10.1139/e86-041.

Please, read the article that I attached.

Best wishes, Mario E. Sigismondi

Check this book (https://link.springer.com/content/pdf/10.1007%2F978-94-007-7708-8.pdf). The standard potential is 0.01 V vs. RHE and the equation is as follow:

C2H6O2 + 2H2O = 2CO2 + 10H+ + 10e-

You can benefit from this article

to my knowledge the product is unstable so it is difficult to measure thank you

Was the reference electrode you used the same as that in the literature?