CN110670084A - Method for preparing salt by adopting electrolysis method - Google Patents

Abstract

The salt is a compound formed by combining metal ions or ammonium ions and acid radical ions in the method for preparing the salt by adopting an electrolytic method, metal oxide, hydroxide or metal carbonate is taken as a raw material, metal, nonmetal or metal oxide is taken as an anode, stainless steel is taken as a cathode, and the electrolysis is carried out by adopting the method of electrolysis of an electrodialysis tank: the method is simple in process, low in price, free of waste residues and waste liquid, clean in production and suitable for large-scale industrial production.

Description

Method for preparing salt by adopting electrolysis method

Technical Field

The invention belongs to the field of salt preparation methods, and particularly relates to a method for preparing salt by adopting an electrolytic method.

Background

The salt refers to a metal ion or ammonium ion (NH)₄⁺) A compound that binds to an acid ion or a non-metal ion. Such as sodium chloride, calcium nitrate, ferrous sulfate and ammonium acetate calcium sulfate, copper chloride, sodium acetate, etc., generally, the salts are the products of metathesis reactions, the salts react with the salts to form new salts and new salts, the salts react with the bases to form new salts and new bases, the salts react with the acids to form new salts and new acids, such as sulfuric acid and sodium hydroxide to form sodium sulfate and water, the sodium chloride reacts with the silver nitrate to form silver chloride and sodium nitrateAnd the like. There are also other reactions that can form salts, such as displacement reactions. Solutions of soluble salts are electrically conductive because of the free mobile ions in the solution, which act as electrolytes.

The methods for preparing metal hypophosphite which have been reported at present include three types of double decomposition method, ion exchange method and electrolytic method.

Double decomposition methods, such as nickel hypophosphite, mainly use nickel sulfate (NiSO)₄) And sodium hypophosphite (NaH)₂PO₂) Carrying out double decomposition reaction to prepare nickel hypophosphite with the lowest solubility, and cooling to separate out nickel hypophosphite crystal-Ni (H)₂PO₂)₂·6H₂And O. However, the obtained crystal product has low purity and can only meet the general requirements of the traditional chemical plating process, so that the application of the process is limited.

The similar method has a narrow application range, depends on the solubility difference of metal hypophosphite, cannot be universally used for all metal hypophosphite, inevitably causes equipment to be not universally used, has high cost, and finally cannot reduce the cost of the metal hypophosphite, so the method cannot be widely applied.

The ion exchange method uses strong acid type cation exchange resin, and first uses the cation exchange resin containing high concentration Ni²⁺Saturating the resin with the solution of the ions, and passing the sodium hypophosphite solution through an ion exchange resin column to allow Na to be adsorbed⁺Is covered with Ni²⁺And exchange to obtain Ni (H)₂PO₂)₂The solution, the product is then crystallized or sold directly as a solution.

The method needs to saturate, elute and regenerate the ion exchange resin, has long operation time and complicated steps and is only suitable for small-scale production. The method is not suitable for all metal hypophosphite, has a narrow application range, cannot be universally used for all metal hypophosphite, inevitably causes equipment to be not universal, has high cost, and finally cannot reduce the cost of the metal hypophosphite, so the method cannot be widely used.

In recent years, there have been patent reports on the production of nickel hypophosphite by an electrodialysis method, which disclose the production of nickel hypophosphite by direct current electrolysis using a 3-compartment, 4-compartment or 5-compartment 6-compartment electrodialysis cell with nickel as an anode and stainless steel, graphite, platinum, etc. as a cathode. The anode is made of nickel plate, which is suitable for nickel hypophosphite, but is not suitable for other metal salts, such as calcium salt and calcium hypophosphite.

The method is not suitable for all metal hypophosphite, has a narrow application range, cannot be universally used for all metal hypophosphite, inevitably causes equipment to be not universal, has high cost, and finally cannot reduce the cost of the metal hypophosphite, so the method cannot be widely used.

Disclosure of Invention

The invention aims to provide a method for preparing salt by adopting an electrolytic method, which has the advantages of simple process, low price, no generation of waste residues and waste liquid, belongs to clean production and is suitable for large-scale industrial production.

The invention aims to provide a method for preparing salt by adopting an electrolytic method, which has the technical points that: the salt is a compound combining metal ions or ammonium ions and acid radical ions, metal oxide, hydroxide or metal carbonate is used as a raw material, metal, nonmetal or metal oxide is used as an anode, stainless steel is used as a cathode, and electrolysis is carried out by adopting an electrodialysis tank electrolysis method: an aqueous solution of an alkali metal salt is placed in the feed chamber, a sulfuric acid solution is placed in the anode chamber, an alkali metal hydroxide solution is placed in the cathode chamber and its adjacent buffer chamber, and an acid solution is placed in the product chamber and its adjacent buffer chamber.

In some embodiments of the invention, the electrolysis method is one of a six-chamber electrodialysis cell direct current electrolysis method or a bipolar membrane electrolysis cell direct current electrolysis method.

In some embodiments of the present invention, the operating conditions of the method for direct current electrolysis in the six-chamber electrodialysis cell are as follows: the working voltage is 2-35V, the working current is 1-500A, the anode potential is 1-10V, and the electrolysis time is 1-100 h.

In some embodiments of the present invention, the metal ion is one of lithium ion, potassium ion, magnesium ion, strontium ion, beryllium ion, nickel ion, calcium ion, tin ion, lead ion, copper ion, cobalt ion, palladium ion, gold ion, silver ion, iron ion, ruthenium ion, rhodium ion, and barium ion.

In some embodiments of the present invention, the acid ion is one of phosphate, hypophosphite, phosphite, chlorate, sulfate, sulfite, hydrochloride, and nitrate.

In some embodiments of the present invention, the alkali metal salt is composed of an alkali metal ion and an acid ion, and the alkali metal ion is one of a lithium ion, a sodium ion, and a potassium ion.

In some embodiments of the present invention, the mass concentration of the aqueous solution of the alkali metal salt is 100 to 900 g/L.

In some embodiments of the invention, the initial mass concentration of the sulfuric acid solution is 1-100 g/L.

In some embodiments of the present invention, the initial mass concentration of the alkali metal hydroxide solution is 1 to 100 g/L. In some embodiments of the invention, the initial mass concentration of the acid solution is 1 to 100 g/L.

Compared with the prior art, the invention has the beneficial effects that:

the salt is a compound formed by combining metal ions or ammonium ions and acid radical ions in the method for preparing the salt by adopting an electrolytic method, metal oxide, hydroxide or metal carbonate is taken as a raw material, metal, nonmetal or metal oxide is taken as an anode, stainless steel is taken as a cathode, and the electrolysis is carried out by adopting the method of electrolysis of an electrodialysis tank: the method is simple in process, low in price, free of waste residues and waste liquid, clean in production and suitable for large-scale industrial production.

Detailed Description

The principle of the invention is illustrated below by way of hypophosphite:

alkali metal hypophosphite is used as a raw material, a metal oxide anode or other insoluble anodes are used as anodes, stainless steel is used as a cathode, a six-chamber electrodialysis cell direct current electrolysis method or a bipolar membrane electrolysis cell is used for preparing hypophosphorous acid, and meanwhile metal oxide or metal hydroxide is used for neutralizing the hypophosphorous acid to prepare the metal hypophosphite. The anion-cation exchange membrane can be perfluorinated ion exchange membrane, hydrocarbon ion exchange membrane, or fluorine-containing hydrocarbon-containing mixed ion exchange membrane.

The method comprises the following specific implementation steps: before electrolysis, a hypophosphite (sodium hypophosphite or potassium hypophosphite) aqueous solution with the concentration of 100-900 g/L is placed in a raw material chamber, an initial solution in an anode chamber is a dilute sulfuric acid solution with the concentration of 1-100 g/L, an initial solution in a cathode chamber and an adjacent buffer chamber is a dilute alkali metal hydroxide solution with the concentration of 1-100 g/L, sodium hydroxide or potassium hydroxide is preferably selected, and an initial solution in a product chamber and an adjacent buffer chamber is a dilute hypophosphorous acid solution with the concentration of 1-100 g/L.

The electrolysis working voltage is 2-35V, the working current is 1-500A, the anode potential is 1-10V, and the electrolysis time is 1-100 hours.

After the electrodialysis cell is electrified with direct current, the anions and the cations in the raw material chamber respectively move to the two poles, the cations move to the cathode, and the anions move to the anode. The anion exchange membrane allows anions to pass through, so the hypophosphite ion (H)₂PO₂^-) Finally enters the product chamber; also cation exchange membranes allow cations to pass through, sodium ions (Na)⁺) And finally into the cathode compartment.

During electrolysis, the insoluble anode, such as a titanium anode, is primarily subjected to electrolysis of water into oxygen and hydrogen ions, according to the equation:

2H₂O＝4H⁺+O₂↑+4e E₀＝+1.229V

hydrogen ions generated by electrolysis enter the product chamber from the anode chamber through the cation exchange membrane, are blocked by the anion exchange membrane and stay in the product chamber, and are combined with hypophosphite ions entering the chamber to generate a hypophosphorous acid product.

The hypophosphorous acid reacts with the added metal oxide or hydroxide, metal carbonate and metal basic carbonate to generate metal hypophosphite.

For monovalent metals, ammonium ions are included, as well as trivalent metal ions, tetravalent metal ions, and the like.

During electrolysis, the cathode chamber mainly generates the reaction of generating hydrogen and hydroxide anions by electrolyzing water, and the reaction formula is as follows:

H₂O＝H⁺+OH^-

2H⁺+2e＝H₂↑ E₀＝+0.0004V

the hydroxide ions produced by electrolysis combine with the sodium ions entering the chamber to produce sodium hydroxide.

In order to control the concentration of the product, the concentration of the product can be analyzed by a titration analysis, an instrumental analysis and the like, the product can be sent to be concentrated and separated, preferably concentrated under reduced pressure, concentrated by heating, concentrated by air drying under normal pressure or directly frozen and separated, the finished metal hypophosphite can be separated, and the crystallized dilute solution is returned to a product chamber of an electrodialysis tank to continuously manufacture the concentrated metal hypophosphite solution.

Of course, the metal hypophosphite liquid can be sold as a product, or the mixed liquid of the metal hypophosphite and the hypophosphorous acid can be sold as a product.

In this case, equivalent sodium hydroxide is generated in the anode chamber, and when the concentration of sodium hydroxide is increased to 300 g/l, the sodium hydroxide can be discharged, frozen and crystallized into solid caustic soda or sold in the form of liquid caustic soda. The solution in the feed chamber and the buffer chamber may remain substantially stationary. When the concentration of sodium ions in the solution in the buffer chamber near the product chamber rises, the solution can be returned to the raw material chamber, and the raw material chamber is continuously supplemented with sodium hypophosphite to maintain the continuous reaction.

The invention prepares hypophosphorous acid by a general process, and then neutralizes the hypophosphorous acid and metal salt to prepare metal hypophosphite. The mass production of hypophosphite of different metals can be realized only by replacing different metal salts, the production of various hypophosphite can be realized on one set of equipment, and the cost is greatly reduced.

The invention has simple process and low price, and is easy for large-scale industrial production. The invention has no waste slag and waste liquid, and belongs to clean production.

For metal phosphites, such as lithium phosphite, potassium phosphite, ammonium phosphite, magnesium phosphite, strontium phosphite, beryllium phosphite, nickel phosphite, calcium phosphite, tin phosphite, lead phosphite, copper phosphite, cobalt phosphite, palladium phosphite, gold phosphite, silver phosphite, iron phosphite, ruthenium phosphite, rhodium phosphite, barium phosphite, it is also possible to obtain metal phosphites by the method described in the present invention, as long as the raw material of the raw material chamber is replaced with phosphorous acid, and it also falls within the scope of the present invention.

Similarly, other ionic compounds, such as metal chloride salts, metal bromide salts, metal iodide salts, metal sulfide salts, metal hydroxide salts, metal acetate salts, metal citrate salts, metal lactate salts, metal formate salts, metal methylsulfonate salts, metal ethylsulfonate salts, and all metal organic salts, can be prepared by replacing the feedstock of the feed chamber with the anionic acid of the corresponding salt, and are also within the scope of the claimed invention.

The technical solutions in the embodiments of the present invention will be clearly and completely described below so that those skilled in the art can better understand the advantages and features of the present invention, and thus the scope of the present invention will be more clearly defined. The embodiments described herein are only a few embodiments of the present invention, rather than all embodiments, and all other embodiments that can be derived by one of ordinary skill in the art without inventive faculty based on the embodiments described herein are intended to fall within the scope of the present invention.

Example 1

The anode material is a titanium anode plate, and the electrode area is 40cm²And the cathode is a stainless steel electrode. The anion-cation exchange membrane is purchased from Shanghai chemical plant, and the membrane area used in electrolysis is 70cm². The volume of solution per compartment of the six-compartment electrodialysis cell was 450 mL. Before electrolysis, the initial solution in the anode chamber is 10g/L sulfuric acid, the raw material chamber is 400g/L sodium hypophosphite, the cathode chamber and the adjacent buffer chamber are both 10g/L sodium hydroxide, the product chamber and the adjacent buffer chamber are both 10g/L hypophosphorous acid, the neutralization tank connected with the product chamber is 10g/L hypophosphorous acid, and metal oxide calcium oxide or calcium carbonate is supplemented as required to generate calcium hypophosphite.

Example 2

With reference to example 1, hypophosphorous acid was prepared. The neutralization tank connected with the product chamber is 10g/L hypophosphorous acid, and metal oxide barium oxide or barium carbonate is added according to the requirement to generate barium hypophosphite.

Example 3

With reference to example 1, hypophosphorous acid was prepared. The neutralization tank connected with the product chamber is 10g/L hypophosphorous acid, and nickel carbonate or nickel hydroxide is added according to the requirement to generate nickel hypophosphite.

Example 4

With reference to example 1, hypophosphorous acid was prepared. And a neutralization tank connected with the product chamber is 10g/L hypophosphorous acid, and cobalt carbonate or cobalt hydroxide is supplemented as required to generate cobalt hypophosphite.

Example 5

The anode material is a titanium anode plate, and the electrode area is 40cm²And the cathode is a stainless steel electrode. The anion-cation exchange membrane is purchased from Shanghai chemical plant, and the membrane area used in electrolysis is 70cm². The volume of solution per compartment of the six-compartment electrodialysis cell was 450 mL. Before electrolysis, the initial solution in the anode chamber is 10g/L sulfuric acid, the raw material chamber is 400g/L sodium chloride, the cathode chamber and the adjacent buffer chamber are both 10g/L sodium hydroxide, the product chamber and the adjacent buffer chamber are both 10g/L hydrochloric acid, the neutralization tank connected with the product chamber is 10g/L hydrochloric acid, and metal oxide tin oxide or tin carbonate is added as required to generate tin chloride.

Example 6

With reference to example 5, hydrochloric acid was prepared. The neutralization tank connected with the product chamber is 10g/L hydrochloric acid, and lead carbonate or lead hydroxide is added according to the requirement to generate lead chloride.

Example 7

The anode material is a titanium anode plate, and the electrode area is 40cm²And the cathode is a stainless steel electrode. The anion-cation exchange membrane is purchased from Shanghai chemical plant, and the membrane area used in electrolysis is 70cm². The volume of solution per compartment of the six-compartment electrodialysis cell was 450 mL. Before electrolysis, the initial solution in the anode chamber is 10g/L sulfuric acid, the raw material chamber is 400g/L potassium sulfate, the cathode chamber and the adjacent buffer chamber are both 10g/L potassium hydroxide, the product chamber and the adjacent buffer chamber are both 10g/L sulfuric acid, the neutralization tank connected with the product chamber is 10g/L sulfuric acid, and ammonia water is supplemented as required to generate ammonium sulfate.

Example 8

Referring to example 7, sulfuric acid was prepared. And a neutralization tank connected with the product chamber is 10g/L sulfuric acid, and metal oxide magnesium oxide or magnesium carbonate is added according to the requirement to generate magnesium sulfate.

Example 9

Referring to example 7, sulfuric acid was prepared. The neutralizing tank connected with the product chamber is 10g/L sulfuric acid, and iron carbonate or iron hydroxide is added according to the requirement to generate ferric sulfate.

Example 10

Referring to example 7, sulfuric acid was prepared. And a neutralization tank connected with the product chamber is 10g/L sulfuric acid, and potassium carbonate or potassium hydroxide is added according to the requirement to generate potassium sulfate.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. A method for preparing salt by adopting an electrolytic method is characterized in that: the salt is a compound combining metal ions or ammonium ions and acid radical ions, metal oxide, hydroxide or metal carbonate is used as a raw material, metal, nonmetal or metal oxide is used as an anode, stainless steel is used as a cathode, and electrolysis is carried out by adopting an electrodialysis tank electrolysis method: an aqueous solution of an alkali metal salt is placed in the feed chamber, a sulfuric acid solution is placed in the anode chamber, an alkali metal hydroxide solution is placed in the cathode chamber and its adjacent buffer chamber, and an acid solution is placed in the product chamber and its adjacent buffer chamber.

2. A method for preparing salt by electrolysis according to claim 1, wherein: the electrolysis method is one of a direct current electrolysis method of a six-chamber electrodialysis cell or a direct current electrolysis method of a bipolar membrane electrolysis cell.

3. A method for preparing salt by electrolysis according to claim 2, wherein: the working conditions of the method for direct current electrolysis of the six-chamber electrodialysis cell are as follows: the working voltage is 2-35V, the working current is 1-500A, the anode potential is 1-10V, and the electrolysis time is 1-100 h.

4. A method for preparing salt by electrolysis according to claim 1, wherein: the metal ions are one of lithium ions, potassium ions, magnesium ions, strontium ions, beryllium ions, nickel ions, calcium ions, tin ions, lead ions, copper ions, cobalt ions, palladium ions, gold ions, silver ions, iron ions, ruthenium ions, rhodium ions and barium ions.

5. A method for preparing salt by electrolysis according to claim 1, wherein: the acid radical ion is one of phosphate radical, hypophosphite radical, phosphite radical, chlorate radical, sulfate radical, sulfite radical, hydrochloride radical and nitrate radical.

6. A method for preparing salt by electrolysis according to claim 1, wherein: the alkali metal salt is composed of alkali metal ions and acid radical ions, and the alkali metal ions are one of lithium ions, sodium ions and potassium ions.

7. A method for preparing salt by electrolysis according to claim 1, wherein: the mass concentration of the alkali metal salt aqueous solution is 100-900 g/L.

8. A method for preparing salt by electrolysis according to claim 1, wherein: the initial mass concentration of the sulfuric acid solution is 1-100 g/L.

9. A method for preparing salt by electrolysis according to claim 1, wherein: the initial mass concentration of the alkali metal hydroxide solution is 1-100 g/L.

10. A method for preparing salt by electrolysis according to claim 1, wherein: the initial mass concentration of the acid solution is 1-100 g/L.