CN115779877A

CN115779877A - Eluent of manganese lithium ion sieve and preparation method and application thereof

Info

Publication number: CN115779877A
Application number: CN202211473143.5A
Authority: CN
Inventors: 杨刚; 年敏; 宋龙艳; 徐徐; 熊丽媛
Original assignee: Jiangsu Liboxing Water Technology Co ltd; Nanjing Tech University
Current assignee: Jiangsu Liboxing Water Technology Co ltd; Nanjing Tech University
Priority date: 2022-11-21
Filing date: 2022-11-21
Publication date: 2023-03-14
Anticipated expiration: 2042-11-21
Also published as: CN115779877B

Abstract

The invention discloses an eluent of a manganese lithium ion sieve, which is prepared from a metal salt aqueous solution, a buffer solution and an acid solution. The application also discloses a preparation method of the eluent and application of the eluent in elution of a precursor of a manganese lithium ion sieve. The method can greatly reduce Mn by utilizing the fact that metal ions in the metal salt aqueous solution can deprive electrons on the surface of the ion sieve ³⁺ The obtained electron number, mn suppression ³⁺ Disproportionating to easily soluble Mn ²⁺ The number of high-valence state manganese ions is kept to the maximum extent, and the dissolution loss of manganese elements in the precursor is reduced, so that the collapse of an ion sieve framework caused by the dissolution loss of the manganese elements is avoided. Ion sieve lambda-MnO prepared by using eluent of the application ₂ After 15 times of circulation, the adsorption capacity can still reach 18.34mg/g.

Description

Eluent of manganese lithium ion sieve and preparation method and application thereof

Technical Field

The invention relates to an eluent of a manganese lithium ion sieve, a preparation method and application thereof.

Background

Lithium and its compounds are important metal elements for promoting social development and improving human happy life, and are widely used in the fields of lithium batteries, ceramics, glass, aerospace industry and the like. The great demand for lithium has resulted in the continuous decrease and shortage of lithium resources. The traditional lithium resource is mainly derived from lithium ore, and with the reduction of the lithium ore, the extraction of the lithium resource from salt lake brine containing a large amount of lithium becomes more important.

The lithium resource in China is rich, lithium ore, salt lake brine and seawater mainly exist, the lithium content of the salt lake brine accounts for 70% of the total lithium resource content, but the magnesium-lithium ratio of the salt lake brine in China is too high, the chemical properties and the radiuses of magnesium and lithium are similar, and the salt lake brine in China is difficult to separate to obtain high-quality lithium by using a traditional method, so the efficiency of extracting lithium from the brine is not high. The adsorption method is the most suitable method, particularly the spinel-type manganese lithium ion sieve in the adsorption method, and is one of the ion sieves with the best prospect for extracting lithium from salt lakes at present due to the good properties of the spinel-type manganese lithium ion sieve, such as high adsorption capacity, good cycle performance, high separation efficiency, environmental friendliness and the like.

The preparation of the ion sieve requires first eluting Li with an eluant ⁺ The method is characterized in that the method is separated from a precursor of an ionic sieve, common eluents comprise hydrochloric acid, nitric acid and sulfuric acid, but the use of the strong acid type eluents can cause the manganese lithium ionic sieve to be easily subjected to disproportionation reaction in the acid washing process to cause Mn ³⁺ Disproportionating to Mn in equal proportion ²⁺ And Mn ⁴⁺ And Mn ²⁺ Can be dissolved into the solution to cause Mn loss in the framework of the ionic sieve, and the Jahn-Teller effect can aggravate Mn loss and framework collapse of the lithium ionic sieve. Therefore, finding more appropriate novel eluents to reduce manganese dissolution loss during elution is still an important work in the field of ion sieve preparation.

Disclosure of Invention

In order to solve the above problems, the present application first proposes a methodThe eluent for the manganese lithium ion sieve is prepared from a metal salt aqueous solution, a buffer solution and an acid solution. Preferably, the acid in the acid solution is an acid corresponding to the acid ion of the metal salt in the aqueous solution of the metal salt. Specifically, the aqueous metal salt solution is AgNO ₃ 、Fe(NO ₃ ) ₃ 、CuSO ₄ 、CuCl ₂ 、Cu(NO ₃ ) ₂ 、FeCl ₃ An aqueous solution of any one of; the concentration of the metal salt in the metal salt aqueous solution is 0.1-1.0mol/L.

The application utilizes partial metal ions to compare Mn ³⁺ Has stronger electron-withdrawing energy, thereby greatly reducing Mn ³ ⁺ The obtained electron number, mn suppression ³⁺ Disproportionating to easily soluble Mn ²⁺ The number of high-valence state manganese ions is kept to the maximum extent, and the dissolution loss of manganese elements in the precursor is reduced, so that the collapse of an ion sieve framework caused by the dissolution loss of the manganese elements is avoided. Since the buffer solution can maintain the solution in a certain pH range, the application utilizes other metal ions to limit Mn ³⁺ While obtaining more electrons, the buffer solution is used to continuously provide H ⁺ Ions with Li in the precursor ⁺ Carry out continuous exchange, ensure Li ⁺ The elution time can be saved, and the elution efficiency can be improved, so that the cyclic adsorption capacity and the selective adsorption performance of the ion sieve are improved. When the eluent is used for eluting the manganese lithium ion sieve, the manganese dissolution loss rate is 0.1-0.5%, the elution time is 0.5-4h, the elution rate of lithium ions is 98.6-99.3%, and the elution time of the existing manganese lithium ion sieve is generally 4-24h.

Lithium ion sieve lambda-MnO produced by eluent in this application ₂ The ion sieve lambda-MnO prepared by the eluent has higher adsorption capacity, cyclic adsorption performance and selective adsorption performance ₂ For Li in salt lake ⁺ The selective distribution coefficient of the catalyst can reach 461.33mg/L, which is much higher than that of lambda-MnO of an ion sieve obtained by hydrochloric acid or nitric acid ₂ For Li in salt lake ⁺ Selective partition coefficient of (a). Ion sieve prepared by eluent of the applicationλ-MnO ₂ After 15 times of circulation, the adsorption capacity can still reach 18.34mg/g, and the ion sieve lambda-MnO obtained by using nitric acid solution ₂ The adsorption capacity of the ion sieve is 6.72mg/g, and the ion sieve is prepared from hydrochloric acid solution ₂ The adsorption capacity of (A) was 4.93mg/g.

Because metal ions are added in the eluent, the metal ions can synchronously enter the eluent formed after the elution is finished and coexist with lithium ions. When the existing manganese lithium ion sieve is used for extracting ions, the concentration of lithium ions is actually only increased, a simple lithium salt solution cannot be obtained, and a crude product of lithium salt is obtained by utilizing the same ion effect and adopting a step precipitation mode, and then is further purified. The eluent obtained by the eluent in the application can still be carried out by adopting the existing lithium salt purification process, only a certain amount of other metal salt byproducts can be added in the purification process, but the newly added metal ions are easier to remove than magnesium ions, the service life of the lithium ion sieve is prolonged, the content of manganese and lithium ions in the eluent is reduced, and the extraction and purification of the lithium ions are generally facilitated.

Preferably, the buffer solution is one or more of an ethanolammonium acetate buffer solution, a sodium formate buffer solution, a potassium hydrogen phthalate buffer solution, a glycine hydrochloric acid buffer solution, a sodium citrate buffer solution, and a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution, and the pH of the buffer solution is 2-6.

The eluent needs to be kept under an acidic condition, and Li in the precursor of the manganese lithium ion sieve ⁺ Can be replaced by H ⁺ And displaced to form lithium vacancies, which have selective adsorption capacity only for lithium ions. The buffer solution has strong buffering capacity, can keep the eluent to be maintained in the required acidic environment, and ensures that H is in a neutral condition ⁺ With Li ⁺ The exchange of (2).

Preferably, the acid solution is any one of sulfuric acid, hydrochloric acid or nitric acid, and the concentration of the acid solution is 0.05-0.5mol/L.

The acid solution is specifically an aqueous acid solution. In order to avoid the precipitation reaction between part of metal ions and acid ions, the acid solution is preferably an acid solution corresponding to the acid ions in the metal salt water solution, for example, when a sulfate salt water solution is adopted, the acid solution is a sulfuric acid solution; when the nitrate aqueous solution is adopted, the acid solution is nitric acid solution; when the hydrochloride aqueous solution is adopted, the hydrochloric acid solution is selected as the acid solution.

The buffer solution can provide a certain amount of H ⁺ But in the course of elution, with H ⁺ The pure buffer solution cannot continuously supply enough H ⁺ Replenishing the consumed H with an amount of acid solution ⁺ And under the action of the buffer solution, the pH value of the eluent can be kept within the range of 2-6 in the whole elution process, thereby ensuring the smooth elution. Too low a concentration of acid solution may not provide sufficient H for the elution process ⁺ So that at the end of elution, the pH of the eluent exceeds 6 and the elution efficiency decreases. When the pH of the eluent is lower than 2, the acid concentration of the solution is too high, and the lithium ion sieve is corroded, so that the structure of the ion sieve is unstable.

Further, the volume ratio of the buffer solution to the metal salt aqueous solution is 100-200, the volume ratio is lower than 100, and the buffer capacity of the buffer solution is influenced due to the overlarge volume of the metal salt aqueous solution; the volume ratio is more than 200, and the volume of the metal salt solution is too small, so that partial salt in the metal salt solution is insoluble, and the elution effect of the eluent is influenced. The molar ratio of acid in the buffer solution to metal ions in the metal salt aqueous solution is 20-191, the molar ratio is lower than 20, and the concentration of metal cations is too high, so that pores on the surface of the ion sieve can be blocked, and lithium ions cannot be normally removed from the ion sieve; the molar ratio is higher than 191, the concentration of metal salt cations is too low, and the metal salt cations cannot play a role in robbing electrons on the surface of the ion sieve. The volume ratio of the buffer solution to the acid solution is 10-50, the volume ratio is lower than 10, and the buffer capacity of the buffer solution is influenced by the overhigh volume of the acid solution; the volume ratio is higher than 50, the volume of the acid solution is too small, in order to ensure H in the eluent ⁺ The concentration of the acid solution is increased, and the acid solution is easily volatilized when the concentration of the acid is too high, so that the preparation of the eluent is not facilitated. Acid in buffer solution and acid solutionThe molar ratio of hydrogen ions is 19-100, the molar ratio is lower than 19, the acid solution concentration is too high to be beneficial to the preparation of the eluent, the molar ratio is higher than 100, the acid concentration is too low to provide enough H for the eluent ⁺ For replacing Li in ionic sieve ⁺ 。

Secondly, the application also provides a preparation method of any one of the eluents, and the preparation method specifically comprises the following steps:

(1) Stirring and mixing the buffer solution and the acid solution uniformly at a set temperature, and forming a prefabricated liquid after the pH of the mixed solution is stable;

(2) Adding the aqueous solution of the metal salt into the prefabricated liquid, and continuously stirring for a set time to prepare the metal salt.

The order of addition of the buffer solution, acid solution and aqueous metal salt solution does not affect the quality or parameters of the final eluent when it is prepared. In this application, the volume of the buffer solution is the largest, followed by the volume of the acid solution, and the volume of the metal salt solution is the smallest. In preparing the eluent, the buffer solution and the acid solution are first mixed homogeneously only in order to be able to rapidly stabilize the pH of the preformulation at the temperatures mentioned above. And after the pre-prepared solution is prepared, adding the aqueous solution of the metal salt, continuously stirring at normal temperature for a set time without continuously maintaining the temperature, and then finishing the preparation of the desorption solution. By adopting the preparation method, the temperature control is only needed when the prefabricated liquid is prepared, and if the heating is needed when the prefabricated liquid is prepared, the heating can be stopped after the metal salt aqueous solution is added, so as to save energy.

Specifically, in order to ensure the production efficiency, in the step (1), the set temperature is 20 to 60 ℃. The set temperature is the same as the subsequent elution temperature, and mainly aims to facilitate the subsequent elution, and when the continuous production is carried out, the prepared eluent can be immediately used for desorbing the precursor or the ion sieve which finishes adsorption, and secondary temperature regulation is not needed, so that the production efficiency is accelerated. Of course, when continuous production is employed, it is necessary to maintain the set temperature in step (2).

In the step (2), the set time is 0.5-1h. The mixing time of less than 0.5h can not make the metal cations uniformly distributed in the solution, and the pickling effect is influenced. The time is longer than 1h, which can increase the preparation time of the eluent and influence the preparation efficiency.

The application further provides an application of the eluent, and the application specifically relates to the application of the eluent in eluting the precursor of the manganese-based lithium ion sieve. When the precursor of the manganese lithium ion sieve is eluted, the liquid-solid ratio of the eluent to the precursor is 0.1-1L/g, the elution temperature is 20-60 ℃, the elution time is 0.5-4h, and the stirring speed is 300-600r/min.

Under the above conditions, the elution of the precursor can be efficiently completed. When the liquid-solid ratio is too low, the eluent cannot provide sufficient amount of H ⁺ It is impossible to complete the elution of lithium ions, and when the liquid-solid ratio is too large, too much H is present ⁺ Resulting in an increase in the dissolution loss of manganese and a decrease in the elution rate of lithium ions.

The elution temperature has little influence on the elution effect, but the proper increase of the elution temperature is beneficial to the increase of H ⁺ The activity of the manganese-containing elution reagent can improve elution efficiency, but the promotion range of elution efficiency is small, the dissolution loss rate of manganese can be improved to a small extent, the cost brought by the improvement of elution temperature and the increase of the dissolution loss rate are considered, and the balance between elution efficiency and dissolution loss rate can be achieved at the temperature. When the elution temperature is lower than 20 ℃, part of ions in the solution can be separated out, the elution effect of the eluent is influenced, and when the elution temperature is higher than 60 ℃, the buffer solution loses the buffer capacity, so that the pH value is greatly increased, and the dissolution loss rate of manganese is rapidly increased.

The elution time is too short to completely remove lithium ions in the precursor, but when the elution rate reaches a certain proportion, the elution time is prolonged, the amount of lithium ions which can be removed is very low, and the dissolution loss rate of manganese ions is continuously increased, so that the too long elution time is not beneficial to the elution of the lithium ion sieve.

Due to the fact that the particle size of the precursor is small and the specific surface area is large, the outer layer structure of the precursor is abraded, collision among the precursors is increased due to rapid stirring, the structure of the precursor is damaged, and the dissolution loss rate of manganese is increased; however, the elution of lithium ions is affected because the eluent cannot enter the inside of the precursor pore passage at a too low stirring speed. Under the stirring speed, the dissolution loss rate of manganese is reduced to the minimum while the lithium ions can be effectively eluted.

Under the elution conditions, the manganese dissolution rate is 0.1-0.5%, and the elution rate of lithium ions is 98.6% -99.3%.

The lithium ion sieve produced by the eluent in the application has higher adsorption capacity and cyclic adsorption performance, and has higher selective adsorption performance.

When the eluent prepared by the method is used for eluting the manganese lithium ionic sieve, the manganese dissolution loss generated in the elution process can be effectively inhibited, and the structural stability of the manganese lithium ionic sieve is improved. The eluent can not only provide continuous H ⁺ With Li ⁺ The exchange is carried out, the elution efficiency is greatly improved, the elution time is shortened, the Mn dissolution loss rate of the manganese lithium ion sieve during elution is greatly reduced, the adsorption capacity, the cyclic adsorption performance and the selective adsorption performance of the ion sieve are improved, and great possibility is provided for the industrialization of the manganese lithium ion sieve.

Drawings

FIG. 1 shows LiMn which is a precursor of a manganese-based lithium ion sieve ₂ O ₄ XRD pattern of (a).

FIG. 2 is a plot of the ion sieve λ -MnO obtained in example 1 after elution with an eluent ₂ XRD pattern of (a).

FIG. 3 shows LiMn as a precursor of manganese ion sieve ₂ O ₄ SEM image of (d).

FIG. 4 shows the ion sieve λ -MnO obtained after elution with an eluent in example 2 ₂ SEM image of (d).

FIG. 5 shows λ -MnO of ion sieve in comparative experiment 1 ₂ (ii) Mn dissolution loss of (B),

showing the case of using a hydrochloric acid solution as an eluent,Elution of precursor LiMn ₂ O ₄ Mn dissolution loss in cases where a represents the eluent and elution precursor LiMn prepared in example 1 ₂ O ₄ The Mn loss in the case of the steel is small.

FIG. 6 shows the ion sieve λ -MnO in comparative experiment 1 ₂ For Li ⁺ A test chart of saturated adsorption amount of (a); ■ Denotes the lambda-MnO of the ion sieve obtained by using the hydrochloric acid solution ₂ The adsorption capacity of (b) represents the adsorption capacity of the ion sieve lambda-MnO obtained by using the eluent in example 1 ₂ The adsorption capacity of (c).

FIG. 7 compares the ion sieve lambda-MnO obtained after acid washing in experiment 2 ₂ A selective adsorption performance test chart for various ions in the salt lake;

denotes the lambda-MnO of the ionic sieve obtained with the nitric acid solution ₂ The distribution coefficient of selectivity for various ions,

shows the ion sieve lambda-MnO obtained using the eluent of example 2 ₂ Distribution coefficients selective to various ions.

FIG. 8 is a graph of the ion sieve λ -MnO obtained after acid washing in comparative experiment 2 ₂ Test pattern of adsorption performance of 15 cycles of (1),

denotes the lambda-MnO of the ion sieve obtained by using nitric acid solution ₂ The adsorption performance is realized after 15 times of circulation,

shows the ion sieve lambda-MnO obtained with the eluent of example 2 ₂ Adsorption performance of 15 cycles.

Detailed Description

The present invention will be further described with reference to specific examples.

Preparation of manganese lithium ion sieve:

taking lithium hydroxide and lithium manganese oxide according to the molar ratio of Li to Mn of 0.5Putting manganese acetate into an ethanol solution, stirring uniformly, then putting into a vacuum drying oven, drying for 12h at the temperature of 80 ℃, grinding the materials, finally putting into a muffle furnace for calcining for 10h at the calcining temperature of 600 ℃, and obtaining a precursor LiMn of the manganese ion sieve with complete structure and good crystallization effect ₂ O ₄ (LMO) with XRD pattern as figure 1 and SEM pattern as figure 3. In each of the following examples and comparative examples, liMn, which is a precursor of the manganese-based ion sieve, was used ₂ O ₄ As a sample.

In the following examples, the precursor LiMn is ₂ O ₄ After the elution is finished, an eluent is formed, the concentration of Mn element and Li element in the eluent is firstly tested by ICP, and then the dissolution loss rate of Mn and the leaching rate of Li are calculated according to the formula (I).

In the formula (I), R _X The leaching rate is the leaching rate of Mn element or Li element, and the unit is wt%;

C _x is the content of Mn or Li, and the unit: mg/L;

v is the volume of the eluent, unit: l;

m _x LiMn as a precursor of an ion sieve weighed during elution ₂ O ₄ Mass of (2), unit: mg;

W _x is Mn or Li in a precursor LiMn ₂ O ₄ In the mass percent, the molecular formula LiMn is calculated ₂ O ₄ The calculation is performed for the reference.

Then, the eluent is filtered, washed and dried to obtain the lambda-MnO ₂ Ion sieve, using adsorption stock solution to make lambda-MnO ₂ The ionic sieve is used for investigating adsorption capacity, selective adsorption and circulating adsorption performance. During suction filtration, the pressure is 0.1MPa; when washing, deionized water is used for washing for 5 times; the drying temperature is 80 ℃ and the time is 2h.

ICP is used for absorbing the concentration of target ions in the original solution before and after absorptionAnd (5) measuring lines. Calculating lambda-MnO according to the formula (II) ₂ Ion sieve pair Li ⁺ The adsorption capacity of (c).

In the formula (II), Q is lambda-MnO ₂ Ion sieve pair Li ⁺ Adsorption capacity of (d), unit: mg g ^-1 ；

C ₀ Concentration of Li before adsorption for the adsorption stock solution, unit: mg/L;

C _li the unit of the concentration of Li after adsorption of the adsorption stock solution is as follows: mg/L;

m is lambda-MnO weighed in adsorption ₂ Mass of the ion sieve, unit: g;

v is the volume of the adsorption stock solution, unit: and L.

Calculating lambda-MnO according to the formula (III) ₂ The distribution coefficient of the ion sieve to each target metal ion.

In the formula (III), K _X Is lambda-MnO ₂ The distribution coefficient of the ion sieve to the target ions, unit: mL. G ^-1 ；

C _x0 Concentration of target metal ions in the solution before adsorption of the adsorption stock solution, unit: mg/L;

C _x concentration of target metal ions in the solution after adsorption of the adsorption stock solution, unit: mg/L;

v is the volume of the adsorption stock solution, unit: l;

m is lambda-MnO ₂ Mass of the ion sieve, unit: g.

calculating lambda-MnO ₂ Partition coefficient of ion sieve to each target metal ion except Li ⁺ In addition, the lower the distribution coefficient of other metal ions is, the lower the adsorption capacity of the ion sieve to the metal ions is, and the lower the Li is ⁺ The higher the distribution coefficient of (A), the higher the distribution coefficient of (B) indicates that the ion sieve is responsible for Li ⁺ The stronger the selective adsorption capacity of (a).

Example 1:

preparing 100mL of ethanol ammonium acetate buffer solution with the pH value of 3.7, putting the ethanol ammonium acetate buffer solution into a water bath kettle, heating the solution to 30 ℃, keeping the temperature, adding 10mL of 0.05mol/L hydrochloric acid solution, uniformly stirring, and then adding 1mL of FeCl with the concentration of 0.5mol/L ₃ After stirring the mixture for 0.5h with an aqueous solution, an eluent was obtained.

0.12g of LiMn precursor was added to the eluent ₂ O ₄ Eluting at 30 deg.C for 0.5h, stirring at 300r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate is 0.26%, and the Li leaching rate is 98.96%. Lambda-MnO of ion sieve ₂ The XRD pattern of fig. 2.

Example 2:

200mL of ethanolic ammonium acetate buffer solution with the pH value of 4 is prepared, the solution is put into a water bath kettle and heated to 35 ℃, the temperature is kept, 4mL of 0.15mol/L nitric acid is added, and 1mL of 0.7mol/L Fe (NO) is added ₃ ) ₃ The eluent is obtained after the solution is mixed and stirred for 0.5 h.

0.3g of LiMn precursor is added to the eluent ₂ O ₄ Eluting at 35 deg.C for 3h with stirring speed of 350r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate was 0.34% and the Li leaching rate was 98.62%. Lambda-MnO of ion sieve ₂ Is shown in fig. 4.

Example 3:

preparing 100mL of ethanol ammonium acetate buffer solution with the pH value of 3.5, putting the solution into a water bath kettle, heating the solution to 60 ℃, keeping the temperature, adding 10mL of 0.05mol/L sulfuric acid, and then adding 0.8mL of 1mol/L CuSO ₄ After the solution is mixed and stirred for 0.8h, eluent is obtained.

0.7g of LiMn precursor is added to the eluent ₂ O ₄ Eluting at 60 deg.C for 3h with stirring speed of 400r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate is 0.23%, and the Li leaching rate is 99.15%.

Example 4:

100mL of sodium formate buffer solution with the pH value of 3.25 is prepared and put into a water bath kettle to be heated to 3The temperature was maintained at 5 ℃ and then 5mL of 0.2mol/L hydrochloric acid and 0.7mL of 0.75mol/L FeCl were added ₃ After the solution is mixed and stirred for 0.9h, eluent is obtained.

0.5g of LiMn precursor is added into the eluent ₂ O ₄ Eluting at 35 deg.C for 3.5h with stirring speed of 400r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate is 0.29%, and the Li leaching rate is 98.87%.

Example 5:

200mL of sodium formate buffer solution with the pH value of 3.3 is prepared, the solution is put into a water bath kettle and heated to 25 ℃, the temperature is kept, 10mL of 0.5mol/L hydrochloric acid is added, and 1.5mL of 0.9mol/L CuCl is added ₂ After the solution is mixed and stirred for 0.6h, eluent is obtained.

0.5g of LiMn precursor is added into the eluent ₂ O ₄ Eluting at 25 deg.C for 4h with stirring speed of 500r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate is 0.17%, and the Li leaching rate is 99.34%.

Example 6:

preparing 100mL of potassium hydrogen phthalate buffer solution with the pH value of 3.5, putting the solution into a water bath kettle, heating the solution to 20 ℃, keeping the temperature, adding 3mL of 0.05mol/L hydrochloric acid, and adding 1mL of 0.1mol/L CuCl ₂ The eluent was obtained after mixing and stirring the solution for 1h.

0.6g of LiMn precursor is added to the above eluent ₂ O ₄ Eluting at 20 deg.C for 1.5h with stirring speed of 500r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate is 0.46%, and the Li leaching rate is 98.58%.

Example 7:

200mL of glycine hydrochloric acid buffer solution with the pH value of 2 is prepared, the solution is placed into a water bath kettle and heated to 25 ℃, the temperature is kept, then 5mL of 0.2mol/L nitric acid is added, and 1.8mL of 0.98mol/L Cu (NO) is added ₃ ) ₂ The eluent is obtained after the solution is mixed and stirred for 0.5 h.

1.5g of LiMn precursor is added to the eluent ₂ O ₄ Eluting at 25 deg.C for 2.5h, stirring at 550r/min to obtain eluateSub-sieve lambda-MnO ₂ The Mn leaching rate was 0.43% and the Li leaching rate was 98.6%.

Example 8:

150mL of sodium citrate buffer solution with the pH value of 4 is prepared, the solution is placed into a water bath kettle and heated to 35 ℃, the temperature is kept, then 10mL of 0.05mol/L sulfuric acid is added, 0.75mL of 0.15mol/L copper sulfate solution is added, and the solution is mixed and stirred for 1 hour to obtain the eluent.

0.25g of LiMn precursor is added into the eluent ₂ O ₄ Eluting at 35 deg.C for 4h with stirring speed of 550r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate was 0.42% and the Li leaching rate was 99.27%.

Example 9:

150mL of disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution with the pH value of 6 is prepared, the solution is placed into a water bath to be heated to 40 ℃, the temperature is kept, 5mL of 0.3mol/L nitric acid is added, 0.9mL of 1mol/L silver nitrate solution is added, and the solution is mixed and stirred for 0.5h to obtain the eluent.

0.3g of LiMn precursor is added to the eluent ₂ O ₄ Eluting at 40 deg.C for 3h with stirring speed of 600r/min to obtain ion sieve lambda-MnO ₂ The Mn leaching rate was 0.37% and the Li leaching rate was 98.93%.

Some of the data in the above examples are shown in Table 1 below.

TABLE 1

Comparative experiment 1

Respectively taking 1g of precursor LiMn ₂ O ₄ The eluent prepared in example 1 and 0.1mol/L hydrochloric acid solution are put into the eluent and eluted at 30 ℃, wherein the volume of the hydrochloric acid solution is equal to that of the eluent prepared in example 1.

In the elution process, samples were taken at 2h, 4h, 6h, 8h, 10h, 12h, 18h and 24h, respectively, and the Mn content in the eluate was measured by ICP to calculate the Mn loss ratio, as shown in FIG. 5. In FIG. 5, the use of hydrochloric acid is shownWhen the solution is used as an eluent, a precursor LiMn is eluted ₂ O ₄ The Mn dissolution loss in the time (g) represents the elution of LiMn as a precursor by using the eluent prepared in example 1 ₂ O ₄ The Mn loss in the case of the steel is small.

As can be seen from fig. 5, the manganese dissolution loss increases gradually with time, reaching 11.49% at 24h of acid washing, when hydrochloric acid solution is used as eluent, whereas the manganese dissolution loss increases in a limited, essentially stable, and is always below 0.5% with the eluent prepared in the present application. The eluent prepared by the method greatly reduces the manganese dissolution loss rate.

Then the ion sieve lambda-MnO obtained after elution is treated ₂ Respectively carrying out adsorption performance tests, wherein the sampling time points are 2h, 4h, 6h, 8h, 10h, 12h, 18h and 24h, and measuring Li by using ICP (inductively coupled plasma) to obtain Li by using an ion sieve ⁺ The adsorption capacity of (2) is shown in FIG. 6. In FIG. 6, \ 9632; shows ion sieve lambda-MnO obtained using a hydrochloric acid solution ₂ The adsorption capacity of (b) represents the adsorption capacity of the ion sieve lambda-MnO obtained by using the eluent in example 1 ₂ The adsorption capacity of (c).

As can be seen from FIG. 6, the resulting ion sieve λ -MnO with two eluents ₂ In this application, the ion sieve eluted by the eluent in this application is used ₂ The adsorption capacity of the ion sieve is higher and can reach 29.64mg/g, and the ion sieve is eluted by hydrochloric acid solution ₂ Has an adsorption capacity of 27.86mg/g, illustrating the lambda-MnO of the ion sieve obtained with the eluent of the present application ₂ The structure of (2) is more complete, and the adsorption effect is better.

Comparative experiment 2

Respectively taking 2g of precursor LiMn ₂ O ₄ The elution was carried out at 35 ℃ for 3h by placing into the eluent prepared in example 2 and a 0.1mol/L nitric acid solution, the volume of which was equal to the volume of the eluent prepared in example 2.

To the obtained ion sieve lambda-MnO ₂ The selectivity and cycle performance tests were performed separately as shown in fig. 7 and 8, respectively. Wherein FIG. 7 is an ion sieve lambda-MnO ₂ The selective adsorption performance test chart of various ions in the salt lake is shown in figure 7,

denotes the lambda-MnO of the ion sieve obtained by using nitric acid solution ₂ The distribution coefficient of selectivity for various ions,

shows the ion sieve lambda-MnO obtained using the eluent of example 2 ₂ Distribution coefficients selective for various ions. Wherein the ionic sieve lambda-MnO obtained by adopting nitric acid solution ₂ For Li ⁺ The partition coefficient of selectivity of (a) was 126.16mL/g, using the ion sieve lambda-MnO obtained from the eluent of example 2 ₂ For Li ⁺ Has a selectivity distribution coefficient of 461.33mL/g, while in Mg ²⁺ 、K ⁺ 、Ca ²⁺ And Na ⁺ In the partition coefficient of selectivity of (1), the ion sieve lambda-MnO obtained by using the eluent of example 2 ₂ Are all low.

When the nitric acid solution is replaced by hydrochloric acid solution, the obtained ion sieve lambda-MnO is obtained ₂ For Li ⁺ The partition coefficient of selectivity (2) was 119.41mL/g.

FIG. 8 shows a lambda-MnO of an ion sieve ₂ The adsorption performance test chart of (1) cycle 15, in fig. 8,

shows the ion sieve lambda-MnO obtained using the eluent of example 2 ₂ Adsorption performance of 15 cycles. After 15 cycles, the ion sieve lambda-MnO obtained from the eluent of example 2 was used ₂ Has an adsorption capacity of 18.34mg/g and an ion sieve lambda-MnO obtained using a nitric acid solution ₂ The adsorption capacity of (2) was 6.72mg/g.

When the nitric acid solution is replaced by hydrochloric acid solution, the obtained ion sieve lambda-MnO ₂ The adsorption capacity after 15 cycles was 4.93mg/g.

As can be seen from FIGS. 7 and 8, the ion sieves lambda-MnO obtained with the eluents of the present application ₂ Has higher selectivity and better cycle performance, and shows that the eluent of the application can improve the lambda-MnO of the ion sieve ₂ Stability of (2).

The above detection shows that when the conventional eluent and the eluent of the present application are used for eluting the ion sieve, the difference of the adsorption capacity of the ion sieve after the first elution is small, but the difference of the adsorption capacity of the ion sieve and the conventional eluent is gradually increased along with the continuous increase of the cycle number, mainly when the conventional simple acid solution is used as the eluent, the content of manganese in the ion sieve is rapidly reduced, the whole structure of the ion sieve is severely damaged, and the adsorption capacity of the ion sieve is greatly reduced. When the eluent in the application is used for elution, the consumption of the manganese element is low, so that the lower pass amplitude of the adsorption capacity of the eluent is low, the cycle number of the ion sieve can be effectively prolonged, and the service life of the ion sieve is prolonged.

Claims

1. The eluent for the manganese lithium ion sieve is characterized by being prepared from a metal salt aqueous solution, a buffer solution and an acid solution.

2. The eluent according to claim 1, characterized in that the aqueous metal salt solution is AgNO ₃ 、Fe(NO ₃ ) ₃ 、CuSO ₄ 、CuCl ₂ 、Cu(NO ₃ ) ₂ 、FeCl ₃ An aqueous solution of any one of; the concentration of the metal salt in the metal salt aqueous solution is 0.1-1.0mol/L.

3. An eluent according to claim 1, characterised in that the buffer solution is one or more of ethanolammonium acetate buffer solution, sodium formate buffer solution, phthalate buffer solution, acetate buffer solution, glycine hydrochloride buffer solution, citrate buffer solution, disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution, the pH of the buffer solution being between 2 and 6.

4. The eluent according to claim 1, characterized in that the acid solution is any one of sulphuric acid, hydrochloric acid or nitric acid, the concentration of the acid solution being 0.05-0.5mol/L.

5. The eluent according to claim 1, characterized in that the volume ratio of the buffer solution to the aqueous solution of the metal salt is between 100 and 200, the molar ratio of the acid in the buffer solution to the metal ions in the aqueous solution of the metal salt is between 20 and 191, the volume ratio of the buffer solution to the acid solution is between 10 and 50, and the molar ratio of the acid in the buffer solution to the hydrogen ions in the acid solution is between 19 and 100.

6. A process for the preparation of an eluent according to any of claims 1 to 5, characterized in that the following steps are used:

(1) Stirring and mixing the buffer solution and the acid solution uniformly at a set temperature, and forming a prefabricated solution after the pH of the mixed solution is stable;

7. The method according to claim 6, wherein the set temperature in the step (1) is 20 to 60 ℃.

8. The method according to claim 6, wherein the set time in the step (2) is 0.5 to 1 hour.

9. Use of an eluent according to any one of claims 1 to 5, characterized in that it is used for eluting a precursor of a manganese-based lithium ion sieve.

10. The application of claim 6, wherein when the manganese lithium ion sieve precursor is eluted, the liquid-solid ratio of the eluent to the precursor is 0.1-1L/g, the elution temperature is 20-60 ℃, the elution time is 0.5-4h, and the stirring speed is 300-600r/min.