Seek help! How to selectively dissolve iron by electrochemical methods!

Thank you! The principle is very simple, according to the Pourbaix diagram, it is easy to find the area where iron dissolves to Fe2+ and gold is stable, but in practice it is not feasible, and I don't know why! Electrolysis with non-aqueous solvents and perchloric acid has some improvements, but it is not very good.

My sample is gold nanowires stretched inside iron, and now the iron is selectively dissolved to extract the gold nanowires. If the voltage is too low, it will pitting and forming some cavities on the surface; If it is too high, the gold will also dissolve, and the resulting gold nanowires are very short, and the upper end can clearly see the shape of the gold being corroded. I don't know how to proceed next, because the little brother used to do less electrochemistry, and I hope the masters will give me more advice!

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In dilute acid, first scan the anodic polarization curve of gold and iron to find out the active dissolution zone of iron, and find a potential value in the active dissolution zone of iron (to ensure that the dissolution potential of gold is insoluble, the dissolution potential of the two is actually very different), and it should be dissolved at this potential! View the original post

There have also been experiments on electrochemical dissolution of alloys, which can basically be dissolved, and you can consider dissolving them all in other methods of separation, although it is troublesome, but you can also consider it. Have you considered stirring with air when you are electrosolving, the effect is good View the original post

My boss gave me a kind of deplating powder to do a dissolution test. We have dissolved several alloys (nickel-iron alloy, nickel-copper alloy, etc.), in the formula of 70g of deplating powder, 70g of sulfuric acid, and one liter of water, the reaction is violent under 80, and it will be dissolved in a few minutes. The solubility is about.

However, the formulation of this deplating powder is unknown. View the original post

Regarding chemical dissolution, that is, the dealloying process, I first tried this, I tried to dissolve with acids, such as hydrochloric acid, nitric acid, sulfuric acid, etc., but the sample quickly turned black and formed oxides. What are the good suggestions for LS to go to the alloy too? Thank you! View the original post

Blackening doesn't have to be oxidized! And maybe the surface of your gold wire is not smooth, just like nano silver powder is black, and nano gold is not golden! Therefore, it is definitely feasible to dissolve it chemically, but only with hydrochloric acid or nitric acid View the original post.

It must be an alkaline solution, otherwise ferrous hydroxide cannot be formed.

The cathodic reaction is 2H2O + 2E-2Oh-H2 first, and it has never been said that there are no hydrogen ions in the alkaline solution.

Second, the cathode is a reaction to gain electrons, and there are no other elements in the solution that can obtain electrons.

1. All can be ......I have tried to use FE as the anode to electrolyze water, and there is a lot of rust, and the anode is corroded after a long time of electrolysis.

Sure, rust itself is a chemical reaction.

Yes, iron is an anode! Inert electrode as cathode! Then use an alkaline solution as an electrolyte, or direct water can also be used, and then heat the resulting white precipitate, preferably iron will turn into iron oxide! Feel free to ask!

The positive electrode of the connected battery, carbon rod or copper and aluminum as the negative electrode containing rust are inserted into the sodium chloride solution, which can go out of rust. Again, this is the galvanic cell principle. It is inappropriate to use the term reduced iron oxide. Equations will not be tested.

You mean electrolytic reduction (ps: who will use this to reduce iron oxide.

Iron oxide is insoluble in water, so there is no free-moving Fe3+ and O2- and cannot be reduced on the electrode.

You can melt it at a high temperature, electrolyze, or dissolve it with hydrochloric acid to get a solution of Fe3+ and then electrolyze it (not necessarily).

Iron does not react in dry air, but oxidizes immediately in moist air.

Chemistry.

The equation is as follows: 4Fe +6 H2O +3 O2 ==4 Fe(OH)3, which is actually the most important way of iron rust in daily life, also called oxygen absorption corrosion. This equation can also be rewritten as:

4Fe +6 H2O +3 O2 ==2 ( where Fe(Oh)3 can be written in the form of hydrated iron oxide. Of course, this is actually an electrochemical reaction, the first step is Fe and H2O and oxygen O2 dissolved in water to form Fe(Oh)2, and then Fe(Oh)2 is further reacted with O2 and H2O in the air to form Fe(Oh)3The generated Fe(OH)3 can also lose water in the middle of the air, and finally become Because in practice, the degree of hydration of rust is different, not all, there are also iron oxide monohydrate, iron oxide dihydrate, etc., in fact, it is a mixture of several hydrated iron oxides, of course, there may also be a very small part of Fe(OH)3 completely lost water and turned into iron oxide, so some books say that rust is iron oxide and iron hydroxide.

mixture. In any case, it is generally indicated. The rust is heated to conceal the water, and a reddish-brown iron oxide powder can finally be obtained.

Of course, in general middle school textbooks, for the sake of teaching convenience, it is said that the main component of rust is Fe2O3, and the hydration part is avoided, otherwise it is too difficult for beginners and easy to confuse. Therefore, if you are a junior high school student, you can think that iron has undergone a (slow oxidation) reaction with oxygen in the air to form iron oxide Fe2O3, also known as ferric oxide.

The chemical equation is: 4Fe +3 O2 ==2 Fe2O3 If you are a high school student, then you have to decide according to the specific topic, which is generally the first time to write the positive reaction of oxygen absorption corrosion:

Fe - 2E-==Fe2+, negative electrode reaction: 2H2O+O2+ 4E- =4Oh-, then the generated anion and cation combine Fe2+ +2Oh- =Fe(Oh)2, and finally the generated Fe(Oh)2 reacts with oxygen and water in air to form Fe(Oh)3, the chemical equation is: 4 Fe(Oh)2+ O2 +2H2O==4Fe(Oh)3

Electrolysis put the alloy on the anode in the use of pure copper as the cathode with cuso4 as the electrolyte The activity of copper is located in front of silver, and the ability of silver to give electrons is weaker than that of copper, and it is difficult to lose electrons at the anode and become cations to dissolve.

When the copper on the anode loses electrons and becomes ionic, the silver is deposited in elemental form at the bottom of the electrolytic cell.

And the silver in the brass was removed.

Anode Cu-2e-=Cu2+

Cathode Cu2++2E-=Cu

Or add concentrated nitric acid, copper can react with concentrated nitric acid, and the iron meets the concentrated nitric acid and passivate, so as to retain it, so that the copper is out, and the iron Cu + 4Hno4 (concentrated) = Cu(NO4)2 + 2NO2 + 2H2O,

Electrochemical methods can. Use your raw material (copper containing iron) as the anode and pure iron as the cathode, put both into the electrolytic cell of the appropriate electrolyte and apply a certain voltage, and you're good to go. The copper iron in the anode dissolves slowly, and the pure iron is formed in the cathode.

Aluminum and iron have special properties:

That is, passivation in cold, concentrated, strongly oxidizing acids ..

Rationale: 1If it is a dilute acid, the oxidation is reduced, and dense oxides cannot be formed on the metal surface, so it reacts to form nitrogen oxides or sulfides, ..

2.This has the advantage of being easy to transport and relatively safe ..

Iron and aluminum can be quickly dissolved in dilute Hno3 or dilute H2SO4, but the dissolution phenomenon in concentrated Hno3 or concentrated H2SO4 is almost completely stopped, carbon steel is usually easy to rust, if an appropriate amount of Ni and Cr is added to the steel, it will become stainless steel. The phenomenon that the chemical stability of a metal or alloy is significantly enhanced due to some factors is called passivation. The phenomenon of metal passivation caused by certain passivators (chemicals) is called chemical passivation. Such as thick HNO3,

Concentrated oxidants such as H2SO4, HCO3, K2Cr2O7, and KMno4 can passivate metals. After the metal is passivated, its electrode potential moves in a positive direction, causing it to lose its original properties, such as passivated iron cannot replace copper in copper salts. In addition, the metal can also be passivated by electrochemical methods, such as placing Fe in H2SO4 solution as the anode, polarizing the anode with an applied current, and using a certain instrument to increase the iron potential to a certain extent, and Fe is passivated.

The phenomenon of metal passivation caused by anodic polarization is called anodic passivation or electrochemical passivation.

Put simply, a protective film is formed on the surface of the aluminium to prevent further reflection. It's different when it's thin.

However, dilute sulfuric acid is still very slow to reflect aluminum. It's the same thing.

Bubbles are formed, and the metal gradually dissolves....

Principle: Microelectrolysis technology is an ideal process for treating high-concentration organic wastewater, called internal electrolysis. It is to electrolyze the sewage by using the potential difference generated by the micro-electrolytic material itself filled in the sewage without electricity, so as to achieve the purpose of degrading organic pollutants. The main components of the waste iron filings filler in the iron-carbon microelectrolysis equipment are iron and carbon, when the iron filings and carbon particles are immersed in acidic sewage, due to the electrode potential difference between iron and carbon, countless microgalvanic cells will be formed in the sewage.

Among them, the iron with low potential becomes the anode, and the carbon with high potential becomes the cathode, and the electrochemical reaction occurs under the condition of acid oxygenation, and the reaction process is as follows: anode (Fe): Fe-2E—Fe2+, E0(Fe2+ Fe)II; Cathode (c):

2H++2E—>H2,E0(H+ H2)=The new ecological hydrogen produced by the galvanic cell reaction undergoes redox reaction with many components in the sewage, which breaks the chain of organic matter and changes the organic functional groups, so that the biodegradability of organic sewage is improved to a certain extent, and Fe(OH)2 and Fe(OH)3 also have flocculation and adsorption effects, so as to achieve the purpose of removing pollutants in sewage. After the pretreatment of iron and carbon microelectrolysis, the acid of the sewage is greatly reduced to 188 degrees, and the amount of neutralizer is reduced. 2) The basic composition of the system is that the iron-carbon micro-electrolysis system is composed of an iron-carbon micro-electrolysis cell, a water distribution system, a blast system and a dosing system.