Why prepare ferrous sulfate and filter while hot

Prevents crystallization from precipitation.

Analysis: Ferrous sulfate solution is easy to deteriorate in the air, pay attention to it when operating:

When producing FeSO4, it is necessary to ensure that there are more iron filings; The concentration of sulfuric acid used should not be too high; After filtration, a few drops of sulfuric acid are added to the Feso4 solution, and the pH is adjusted to about 1 2, because under acidic conditions, Fe2 is relatively stable; Filtration should be rapid, so that the time of FeSo4 solution in the air is as short as possible; The temperature should not be high when concentrating crystallization. These measures can reduce the chance of oxidation of ferrous sulfate solutions.

Excess iron can inhibit the oxidation of ferric, which then reacts with iron to form ferric ions. Because the preparation of ferrous sulfate is the reaction of sulfuric acid and iron... And bivalent iron is susceptible to oxidation.

Then we use ion reaction to express it, which can be seen as sulfuric acid and iron into trivalent iron ions. So there must be an excess of iron...

The process of preparing ferrous sulfate is a process of recrystallization.

The basic requirement for recrystallization is that at higher temperatures, the substances to be crystallized are dissolvable, while the impurities are not.

The concentration of the solution during recrystallization is very high (even close to that of the saturated solution), and to maintain the high concentration, a high temperature is required, and once the temperature is lowered, some ferrous sulfate will soon precipitate. If it is not filtered while it is hot at this time, the precipitated ferrous sulfate will contain more impurities.

The purpose of decompression is to speed up the filtration and prevent crystallization from falling while the temperature is hot.

Because of the preparation of ferrous sulfate.

It is a reaction with sulfuric acid and iron. Then we react with ions.

It can be seen as sulfuric acid and iron into ferric ions, and then ferric iron reacts with iron to form ferric ions. So there must be an excess of iron, and ferric iron is susceptible to oxidation, and excess iron can inhibit the oxidation of ferric iron.

Ferrous sulfate is an inorganic substance with the chemical formula FeSO4, and the appearance of the socks is white powder and odorless. Its crystalline hydrate is heptahydrate at room temperature, commonly known as "green alum", light green crystals, weathered in dry air, oxidized to brown basic iron sulfate on the surface in humid air, and becomes tetrahydrate at 65. Slippery ferrous sulfate is soluble in water and almost insoluble in ethanol.

Its aqueous solution oxidizes slowly in the air when it is cold, and oxidizes faster when it is hot.

Preparation of ferrous sulfate:

The industrial preparation method of ferrous sulfate is very common, and as a scientific research, you can generally buy branded reagents on platforms such as chemical sources**, or you can prepare them in the laboratory by yourself, which is quick and easy:

1.It can be prepared directly by reacting iron powder with dilute sulfuric acid. Fe + H2SO4 (dilute) = H2 + FeSO4, the slightly acidic ferrous sulfate solution generated by the reaction is clarified to remove impurities, and then cooled and crystallized, dehydrated, and ferrous sulfate is prepared.

2.It can be obtained by reacting copper sulfate solution with iron, and the reaction equation is: CuSO4 + Fe = FeSO4 + Cu (this reaction type is a displacement reaction), and it is also necessary to remove impurities, crystallization and dehydration.

Purpose:1Feed additives Feed grade ferrous sulfate is generally an ferrous sulfate monohydrate compound, mainly used as a supplement for iron in feed processing, and can also detoxify the meal toxin of cottonseed cake seeds for feed.

2.Water treatment The sedimentation rate of ferrous sulfate is fast and the corrosiveness is small, so it is often used as a flocculant for water treatment, and the effect of decolorization of printing and dyeing sewage is also very good;

By reacting with sulfides, phosphates, etc., ferrous sulfate can be used as a precipitant to form a precipitate that is insoluble in water; The ferrous ions in ferrous sulfate are very easy to oxidize, which can reduce hexavalent chromium in wastewater to trivalent and replace heavy metal ions.

3.Medicinal For iron deficiency anemia, ferrous sulfate has a very good ** effect and is already the most commonly used way of iron supplementation, but after the symptoms are relieved, it should not be taken continuously. For chronic blood loss caused by uterine fibroids, ferrous sulfate can act as a blood tonic.

4.Agriculture Ferrous sulfate is also widely used in agriculture, often known as iron fertilizer, mainly to regulate the pH of the soil and promote the formation of chlorophyll; For iron trees and other flowering trees that like to shoot acid, sulfur attack refers to the fact that ferrous acid is almost impossible to be deficient, which can effectively prevent and control yellowing; make pesticides to prevent and control wheat smut; As a herbicide, it can remove moss on lichens and tree trunks.

1. First of all, according to the amount of Feso4 to be prepared, calculate the amount of H2SO4 2 needed, and continuously add iron to H2SO4, and at the beginning what is obtained is Fe2(SO4)3, which can be seen from the color of the solution (yellow), if you want to use the H2 generated, then you can also collect it.

3. Continue to add iron, when the H2SO4 reaction is completed, it will be found that there will be no bubbles coming out of the solution, then the color of the solution will change, change to light green, continue to add iron, until a small amount of iron is found to be excessive, a small amount of iron here, one is to make all Fe3+ all Fe2+ to Fe2+; The second is to prevent Fe2+ from being oxidized by O2.

This gives a FeSo4 solution.

If the FeSo4 solid is to be obtained, then the solution needs to be treated.

The solution obtained by heating with low heat makes the water continue to volatilize, pay attention to the fire should not be large, otherwise it is easy to be oxidized, so that FeSo4 will slowly get its solid substance.

A small amount of iron impurities is inevitable!

A process of preparing high-purity ferrous sulfate by using slag, it is a one-sail rolling reaction of pyrite slag and ultra-fine iron sulfur preparation ore and industrial sulfuric acid for acid dissolution and reduction to obtain ferrous sulfate slurry, dissolve and filter the slurry to obtain ferrous sulfate solution, concentrate, cool, crystallize and centrifuge the ferrous sulfate solution to obtain high-purity ferrous sulfate products--- ferrous sulfate crystals heptahydrate, which can be directly used in the preparation of high-grade iron oxide series pigments. Most of the crystallized mother liquor goes to the reaction kettle, and the free sulfuric acid, iron sulfate, ferrous sulfate and other active ingredients are in it. The purity of ferrous sulfate produced by the present invention is greater than that, the consumption of sulfuric acid is low, and the purity of ferrous sulfate heptahydrate produced is high, and it is directly used in the preparation of iron oxide series pigments, and the process of using ferrous sulfate to prepare iron oxide series pigments is simplified, and it is the most critical technology in the preparation of high-grade iron pigments by using slag.

The process flow is as follows:

Iron is an essential element for the body, a component of hemoglobin, myoglobin, cytochromes, and certain enzymes (cytochromeases, cytochrome oxidases, peroxidases, etc.). Animals are generally not deficient in iron when the body has sufficient nutrition or sufficient iron supplementation, but when acute or chronic blood loss, as well as iron deficiency anemia caused by certain diseases, iron supplements** are administered, and the effect is obvious and rapid. Iron is absorbed in the duodenum in the form of ferrous ions, and can also be absorbed from the stomach and lower part of the small intestine in the presence of iron deficiency.

However, calcium, phosphorus, and tannic acid precipitate iron salts, hindering iron absorption. It is mainly used for iron deficiency anemia of chronic anemia, malnutrition, pregnant animals and lactating piglets.

In the preparation of ammonium ferrous sulfate, the filtered Feso4 solution must be filtered while it is hot Reason: to prevent crystal precipitation.

Analysis: ferrous sulfate solution is easy to deteriorate in the air, and it should be noted during operation: when preparing Feso4, it is necessary to ensure that there are more iron filings; The concentration of sulfuric acid used should not be too high; After filtration, a few drops of sulfuric acid are added to the Feso4 solution, and the pH is adjusted to about 1 2, because under acidic conditions, Fe2 is relatively stable; Filtration should be rapid, so that the time of FeSo4 solution in the air is as short as possible; The temperature should not be high when concentrating crystallization.

These measures can reduce the chance of oxidation of ferrous sulfate solutions.

Introduction: Ammonium ferrous sulfate, commonly known as moiré salt, is a light green transparent crystal, soluble in water, more stable than ordinary ammonium ferrous salt in the air, and is not easy to be oxidized. FeSO4 is easily oxidized in the air, and SCN can be used to test whether the FeSO4 solution is deteriorating.

Because the solubility of ammonium ferrous sulfate in water is smaller than that of the simple salts ammonium sulfate and ferrous sulfate that compose it within 0 60, as long as they are dissolved and mixed in water in a certain proportion, the crystals of ammonium ferrous sulfate can be prepared. The method is: dissolve metal iron in dilute sulfuric acid to prepare ferrous sulfate.

When the temperature decreases, FeSo4 precipitates 1171

Iron must be excessive.

Because in the preparation process, if the iron is not excessive, the iron ions in ferrous sulfate are easily oxidized into ferric ions by the oxygen in the air, and it becomes ferric sulfate! When there is an excess of iron, the iron ions that are oxidized to trivalent can also be reduced to ferrous iron by the excess iron! So there must be an excess of iron.

Anhydrous ferrous sulfate is a white powder, containing crystalline water is light green crystals, the crystals are commonly known as "green alum", and the soluble in aqueous solution is light green. Ferrous sulfate can be used as a chromatographic analysis reagent, drip analysis for the determination of platinum, selenium, nitrite and nitrate. Ferrous sulfate can also be used as a reducing agent, to make ferrites, to purify water, to polymerize catalysts, photographic plates, etc.

It's iron to be excessive. Because the preparation of ferrous sulfate is the reaction of sulfuric acid and iron... Then we use ion reaction to express that it can be seen as sulfuric acid and iron into ferric ions, and then the ferric iron reacts with iron to form ferric ions...

So there must be an excess of iron... And bivalent iron is susceptible to oxidation. And excess iron can inhibit the oxidation of ferric iron...

Iron and dilute sulfuric acid reaction (Fe + H2SO4 = FeSO4 + H2), iron and copper sulfate reaction (Fe + Cu So4 = Cu + FeSo4), ferrous oxide and sulfuric acid reaction (Fe + H2SO4 = FeSO4 + H2O), iron and iron sulfate reaction [Fe + Fe2 (SO4) 3 = 3 FeSo4].

1 Iron and dilute sulfuric acid.

2 Iron and copper sulphate solution.

3 Iron and ferric sulfate solution.

4 Ferrous oxide and dilute sulfuric acid.

Iron reacts with dilute sulfuric acid;

Iron oxide reacts with dilute sulfuric acid;