阅读说明：本技术 铝空气电池电解废液制备镁铝锌水滑石的方法及其用途 (Method for preparing magnesium-aluminum-zinc hydrotalcite from aluminum-air battery electrolysis waste liquid and application thereof ) 是由 施学金 唐智华 赵学敏 任珊珊 于 2021-08-20 设计创作，主要内容包括：本发明公开了铝空气电池电解废液制备镁铝锌水滑石的方法及其用途。该制备方法包括方案1或方案2,方案1是预先将铝空气电池电解废液进行过滤,并将滤液与镁源和锌源反应、固液分离,得到氢氧根型镁铝锌水滑石,再将氢氧根型镁铝锌水滑石和碳源反应、过滤得到镁铝锌水滑石；方案2是将铝空气电池电解废液进行过滤得到的滤液直接与镁源、锌源和碳源反应,并进行固液分离得到镁铝锌水滑石。采用该方法能实现铝空气电池电解废液的资源化利用,并获得附加值较高的镁铝锌水滑石,既能降低水滑石的生产成本,而且制得的镁铝锌水滑石杂质含量较低、晶型易控制、设备操作简单、生产成本较低、节能环保、易实现工业化生产。(The invention discloses a method for preparing magnesium-aluminum-zinc hydrotalcite from electrolytic waste liquid of an aluminum-air battery and application thereof. The preparation method comprises a scheme 1 or a scheme 2, wherein the scheme 1 is to filter the electrolytic waste liquid of the aluminum air battery in advance, react the filtrate with a magnesium source and a zinc source, and carry out solid-liquid separation to obtain hydroxyl type magnesium-aluminum-zinc hydrotalcite, and then react the hydroxyl type magnesium-aluminum-zinc hydrotalcite with a carbon source and filter to obtain magnesium-aluminum-zinc hydrotalcite; and in the scheme 2, the filtrate obtained by filtering the electrolytic waste liquid of the aluminum air battery directly reacts with a magnesium source, a zinc source and a carbon source, and the magnesium-aluminum-zinc hydrotalcite is obtained by carrying out solid-liquid separation. The method can realize resource utilization of the electrolytic waste liquid of the aluminum-air battery, and obtain the magnesium-aluminum-zinc hydrotalcite with higher added value, so that the production cost of the hydrotalcite can be reduced, and the prepared magnesium-aluminum-zinc hydrotalcite has the advantages of lower impurity content, easy crystal form control, simple equipment operation, lower production cost, energy conservation, environmental protection and easy realization of industrial production.)

1. A method for preparing Mg-Al-Zn hydrotalcite is characterized in that the method comprises a scheme 1 or a scheme 2,

scheme 1 includes:

(1) filtering the electrolytic waste liquid of the aluminum-air battery so as to obtain a first filtrate;

(2) mixing the first filtrate, a magnesium source and a zinc source for reaction so as to obtain a mixed solution containing hydroxide radical type magnesium-aluminum-zinc hydrotalcite;

(3) carrying out solid-liquid separation on the mixed solution containing the hydroxyl type magnesium-aluminum-zinc hydrotalcite so as to obtain hydroxyl type magnesium-aluminum-zinc hydrotalcite and a second filtrate;

(4) reacting the hydroxyl type magnesium-aluminum-zinc hydrotalcite with a carbon source, filtering to obtain a third filtrate and magnesium-aluminum-zinc hydrotalcite,

the scheme 2 comprises the following steps:

(i) filtering the electrolytic waste liquid of the aluminum-air battery to obtain a fourth filtrate;

(ii) mixing the fourth filtrate, a magnesium source, a zinc source and a carbon source for reaction so as to obtain a mixed solution containing magnesium, aluminum and zinc hydrotalcite;

(iii) and carrying out solid-liquid separation on the mixed liquid containing the magnesium-aluminum-zinc hydrotalcite so as to obtain a fifth filtrate and the magnesium-aluminum-zinc hydrotalcite.

2. The method according to claim 1, wherein in the step (1), the aluminum-air battery electrolysis waste liquid comprises potassium hydroxide and sodium hydroxide.

3. The method of claim 1, wherein step (2) satisfies at least one of the following conditions:

the magnesium source comprises at least one selected from magnesium hydroxide, magnesium chloride, magnesium oxide, magnesium sulfate, magnesium nitrate and magnesium carbonate;

the zinc source comprises at least one selected from zinc hydroxide, zinc chloride, zinc oxide, zinc sulfate, zinc nitrate and zinc carbonate;

the reaction temperature is 40-150 ℃, and the reaction time is 2-12 h.

4. The method of claim 1, wherein step (3) satisfies at least one of the following conditions:

the solid-liquid separation is realized by vacuum filtration, pressure filtration, centrifugal separation or gravity sedimentation;

further comprising: supplementing alkali to the second filtrate so as to obtain a regenerated electrolyte for the aluminum-air battery;

further comprising: and (3) washing and drying the hydroxyl type magnesium-aluminum-zinc hydrotalcite by adopting water, and reusing the washing water as a reaction medium in the step (2).

5. The method according to claim 4, wherein the concentration of OH-in the second filtrate is 1-4 mol/L, and the concentration of OH-in the regenerated electrolyte is 5-8 mol/L.

6. The method of claim 1, wherein step (4) satisfies at least one of the following conditions:

the carbon source comprises at least one selected from potassium carbonate, sodium bicarbonate, potassium bicarbonate and carbon dioxide;

the reaction is carried out by adopting a hydrothermal synthesis method, wherein the reaction temperature of the hydrothermal synthesis method is 60-200 ℃, the pH value is 8-12, and the reaction time is 4-15 h;

the reaction is carried out by adopting a roasting reduction method, and the roasting reduction method comprises the following steps: roasting the hydroxyl type magnesium-aluminum-zinc hydrotalcite at 400-800 ℃ for 3-8 h; and mixing and stirring the roasted product and a solution containing a carbon source for 12-24 hours.

7. The method of any one of claims 1-6, wherein scheme 1 further comprises:

(5) evaporating and concentrating the third filtrate to obtain carbonate or concentrated solution; recycling at least a portion of the carbonate or concentrate to step (4).

8. The method of claim 1, wherein scheme 2 satisfies at least one of the following conditions:

in the step (i), the electrolytic waste liquid of the aluminum-air battery comprises potassium hydroxide and sodium hydroxide;

in step (ii), the magnesium source comprises at least one selected from magnesium hydroxide, magnesium chloride, magnesium oxide, magnesium sulfate, magnesium nitrate and magnesium carbonate;

in step (ii), the zinc source comprises at least one selected from zinc hydroxide, zinc chloride, zinc oxide, zinc sulfate, zinc nitrate, zinc carbonate;

in step (ii), the carbon source comprises at least one selected from potassium carbonate, sodium bicarbonate, potassium bicarbonate, carbon dioxide;

in the step (ii), the reaction temperature is 40-150 ℃, and the reaction time is 2-12 h;

in the step (iii), the solid-liquid separation is realized by vacuum filtration, pressure filtration, centrifugal separation or gravity settling;

step (iii) further comprises: (iii) washing and drying the magnesium aluminium zinc hydrotalcite with water and recycling the washing water as a reaction medium in step (ii).

9. The method of claim 1 or 8, wherein scheme 2 further comprises:

(iv) evaporating and concentrating the fifth filtrate to obtain carbonate or concentrated solution; (iii) recycling at least a portion of the carbonate or concentrate to step (ii).

10. Use of the method of any one of claims 1 to 9 in recycling aluminum air battery electrolysis waste liquid, producing magnesium aluminum zinc hydrotalcite, and improving thermal stability and initial colorability of PVC.

Technical Field

The invention belongs to the field of resource recycling, and particularly relates to a method for preparing magnesium-aluminum-zinc hydrotalcite from electrolytic waste liquid of an aluminum-air battery and application of the magnesium-aluminum-zinc hydrotalcite.

Background

The aluminum-air battery has high specific energy, is safe and environment-friendly, has rich raw materials, and has wide development prospect in the aspects of standby power supplies, electric automobiles, communication equipment and the like. Discharging the cathode high-purity aluminum or aluminum alloy of the aluminum-air battery in an alkaline system of 3-8 mol/L potassium hydroxide or sodium hydroxide solution. During the discharge process, the aluminum anode is oxidized and dissolved with OH^-Reaction to produce Al (OH)₄ ^-. When Al (OH)₄ ^-When the concentration in the electrolyte reaches a certain value, aluminum hydroxide is separated out, and simultaneously a large amount of Al (OH)₄ ^-The viscosity and conductivity of the electrolyte can be seriously influenced, and the performance attenuation of the battery is finally influenced; when the performance of the battery is attenuated to a certain degree, the electrolyte is changed into waste electrolyte, and then the aluminum air battery is in the optimal discharge state by replacing fresh electrolyte. However, the replaced waste electrolyte contains a large amount of Al (OH)₄ ^-It is difficult to separate and recycle the alkaline substance.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention aims to provide a method for preparing magnesium-aluminum-zinc hydrotalcite from the electrolysis waste liquid of an aluminum-air battery and application thereof. The preparation method can realize resource utilization of the electrolytic waste liquid of the aluminum-air battery, and obtain the magnesium-aluminum-zinc hydrotalcite with higher added value, so that the production cost of the magnesium-aluminum-zinc hydrotalcite can be effectively reduced, the prepared magnesium-aluminum-zinc hydrotalcite has lower impurity content, easy crystal form control, simple equipment operation, lower production cost, energy conservation and environmental protection, and easy realization of industrial production, and in addition, the prepared magnesium-aluminum-zinc hydrotalcite can be used for PVC to remarkably improve the thermal stability, initial colorability and transparency of the PVC.

The present application is mainly proposed based on the following findings of the inventors:

can be prepared by mixing the waste electrolyte alkaline material of aluminum air battery with Al (OH)₄ ^-And the separation realizes the recycling of aluminum in the waste electrolyte and the regeneration of the electrolyte. In addition, hydrotalcite acts as heat for PVCIn the case of the stabilizer, since the initial coloring property of the Mg-Al binary hydrotalcite is generally poor, the PVC product is easily yellowed, while the zinc element has excellent initial coloring property, Mg-Al-Zn hydrotalcite ([ Mg)²⁺ _1-xAl³⁺ _2xZn²⁺ _1-x(OH)₂](CO₃ ^2-)_x/n·mH₂O, wherein x is more than or equal to 0.25 and less than or equal to 0.5, n is more than or equal to 0 and less than or equal to 0.1, and m is more than or equal to 0 and less than or equal to 4) has unique structure and physical and chemical properties, so that the special performance is determined, and compared with magnesium-aluminum hydrotalcite, the magnesium-aluminum-zinc hydrotalcite can obviously improve the initial colorability and transparency of PVC when being used as a novel heat stabilizer of PVC. Based on this, Al (OH) in the waste electrolyte of aluminum air battery can be utilized₄ ^-The magnesium-aluminum-zinc hydrotalcite is used as an aluminum source to obtain magnesium-aluminum-zinc hydrotalcite with higher added value.

To this end, in one aspect of the invention, the invention proposes a process for preparing magnesium aluminium zinc hydrotalcite. According to an embodiment of the present invention, the method comprises scheme 1 or scheme 2,

scheme 1 includes:

(1) filtering the electrolytic waste liquid of the aluminum-air battery so as to obtain a first filtrate;

(2) mixing the first filtrate, a magnesium source and a zinc source for reaction so as to obtain a mixed solution containing hydroxide radical type magnesium-aluminum-zinc hydrotalcite;

(3) carrying out solid-liquid separation on the mixed solution containing the hydroxyl type magnesium-aluminum-zinc hydrotalcite so as to obtain hydroxyl type magnesium-aluminum-zinc hydrotalcite and a second filtrate;

(4) reacting the hydroxyl type magnesium-aluminum-zinc hydrotalcite with a carbon source, filtering to obtain a third filtrate and magnesium-aluminum-zinc hydrotalcite,

the scheme 2 comprises the following steps:

(i) filtering the electrolytic waste liquid of the aluminum-air battery to obtain a fourth filtrate;

(ii) mixing the fourth filtrate, a magnesium source, a zinc source and a carbon source for reaction so as to obtain a mixed solution containing magnesium, aluminum and zinc hydrotalcite;

(iii) and carrying out solid-liquid separation on the mixed liquid containing the magnesium-aluminum-zinc hydrotalcite so as to obtain a fifth filtrate and the magnesium-aluminum-zinc hydrotalcite.

The method for preparing the magnesium-aluminum-zinc hydrotalcite of the embodiment of the invention has the following advantages: (a) when the scheme 1 is adopted, the magnesium source and the zinc source are added into the electrolytic waste liquid of the aluminum-air battery to generate the magnesium-aluminum-zinc hydrotalcite, the additive is single, and the recycling of the electrolytic waste liquid of the aluminum-air battery can be realized. (b) The prepared magnesium-aluminum-zinc hydrotalcite has the advantages of low impurity content, easy crystal form control, simple equipment operation, low production cost, energy conservation, environmental protection and easy realization of industrial production. (c) The magnesium-aluminum-zinc hydrotalcite with higher added value is recovered by utilizing the electrolysis waste liquid, so that the production cost of the aluminum-air battery and the preparation cost of the magnesium-aluminum-zinc hydrotalcite are greatly reduced. (d) The third filtrate in the scheme 1 and the fifth filtrate in the scheme 2 can be fully utilized by evaporation and concentration. (e) Provides a new direction for the preparation of the magnesium-aluminum-zinc hydrotalcite and the recycling of the electrolytic waste liquid of the aluminum-air battery. (f) The prepared magnesium-aluminum-zinc hydrotalcite can be used as a heat stabilizer of PVC, and can improve the initial colorability and transparency of PVC while improving the thermal stability of PVC.

In addition, the method for preparing magnesium-aluminum-zinc hydrotalcite according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the invention, in step (1), the aluminum-air battery electrolysis waste liquid comprises potassium hydroxide and sodium hydroxide.

In some embodiments of the invention, step (2) satisfies at least one of the following conditions: the magnesium source comprises at least one selected from magnesium hydroxide, magnesium chloride, magnesium oxide, magnesium sulfate, magnesium nitrate and magnesium carbonate; the zinc source comprises at least one selected from zinc hydroxide, zinc chloride, zinc oxide, zinc sulfate, zinc nitrate and zinc carbonate; the reaction temperature is 40-150 ℃, and the reaction time is 2-12 h.

In some embodiments of the invention, step (3) satisfies at least one of the following conditions: the solid-liquid separation is realized by vacuum filtration, pressure filtration, centrifugal separation or gravity sedimentation; further comprising: supplementing alkali to the second filtrate so as to obtain a regenerated electrolyte for the aluminum-air battery; further comprising: and (3) washing and drying the hydroxyl type magnesium-aluminum-zinc hydrotalcite by adopting water, and reusing the washing water as a reaction medium in the step (2).

In some embodiments of the invention, OH in the second filtrate^-The concentration of (a) is 1-4 mol/L, OH in the regenerated electrolyte^-The concentration of (b) is 5-8 mol/L.

In some embodiments of the invention, step (4) satisfies at least one of the following conditions: the carbon source comprises at least one selected from potassium carbonate, sodium bicarbonate, potassium bicarbonate and carbon dioxide; the reaction is carried out by adopting a hydrothermal synthesis method, wherein the reaction temperature of the hydrothermal synthesis method is 60-200 ℃, the pH value is 8-12, and the reaction time is 4-15 h; the reaction is carried out by adopting a roasting reduction method, and the roasting reduction method comprises the following steps: roasting the hydroxyl type magnesium-aluminum-zinc hydrotalcite at 400-800 ℃ for 3-8 h; and mixing and stirring the roasted product and a solution containing a carbon source for 12-24 hours.

In some embodiments of the invention, scheme 1 further comprises: (5) evaporating and concentrating the third filtrate to obtain carbonate or concentrated solution; recycling at least a portion of the carbonate or concentrate to step (4).

In some embodiments of the invention, scheme 2 satisfies at least one of the following conditions: in the step (i), the electrolytic waste liquid of the aluminum-air battery comprises potassium hydroxide and sodium hydroxide; in step (ii), the magnesium source comprises at least one selected from magnesium hydroxide, magnesium chloride, magnesium oxide, magnesium sulfate, magnesium nitrate and magnesium carbonate; in step (ii), the zinc source comprises at least one selected from zinc hydroxide, zinc chloride, zinc oxide, zinc sulfate, zinc nitrate, zinc carbonate; in step (ii), the carbon source comprises at least one selected from potassium carbonate, sodium bicarbonate, potassium bicarbonate, carbon dioxide; in the step (ii), the reaction temperature is 40-150 ℃, and the reaction time is 2-12 h; in the step (iii), the solid-liquid separation is realized by vacuum filtration, pressure filtration, centrifugal separation or gravity settling; step (iii) further comprises: (iii) washing and drying the magnesium aluminium zinc hydrotalcite with water and recycling the washing water as a reaction medium in step (ii).

In some embodiments of the invention, scheme 2 further comprises: (iv) evaporating and concentrating the fifth filtrate to obtain carbonate or concentrated solution; (iii) recycling at least a portion of the carbonate or concentrate to step (ii).

In still another aspect of the invention, the invention provides the use of the method for preparing the magnesium-aluminum-zinc hydrotalcite in the recovery of aluminum-air battery electrolysis waste liquid, the production of the magnesium-aluminum-zinc hydrotalcite, and the improvement of PVC thermal stability and initial colorability. Compared with the prior art, the application has the following advantages: can realize the resource utilization of the electrolytic waste liquid of the aluminum-air battery, can reduce the production cost of the aluminum-air battery and the magnesium-aluminum-zinc hydrotalcite, and can obviously improve the initial colorability and the transparency of the PVC on the basis of improving the thermal stability of the PVC.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a flow diagram of a process for preparing magnesium aluminum zinc hydrotalcite according to scheme 1.

FIG. 2 is a flow diagram of a method for preparing magnesium aluminum zinc hydrotalcite according to scheme 2.

FIG. 3 is a flow chart of a method for preparing Mg-Al-Zn hydrotalcite according to the present invention using scheme 1.

FIG. 4 is a flow chart of a method for preparing magnesium aluminum zinc hydrotalcite according to the invention using scheme 2.

FIG. 5 is an SEM image of Mg-Al-Zn hydrotalcite prepared in example 1 of the present invention.

FIG. 6 is a TG-DSC graph of Mg-Al-Zn hydrotalcite prepared in example 1 of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In one aspect of the invention, a method for preparing magnesium aluminum zinc hydrotalcite is provided. According to an embodiment of the invention, the method comprises scheme 1 or scheme 2, wherein both scheme 1 and scheme 2 are proposed based on the same inventive concept, namely magnesium-aluminum hydrotalcite is obtained by reacting an aluminum source, a zinc source and a carbon source in electrolytic waste liquid based on the aluminum source and alkaline conditions. The preparation method can realize resource utilization of the electrolytic waste liquid of the aluminum-air battery, and obtain the magnesium-aluminum-zinc hydrotalcite with higher added value, so that the production cost of the magnesium-aluminum-zinc hydrotalcite can be effectively reduced, the prepared magnesium-aluminum-zinc hydrotalcite has lower impurity content, easy crystal form control, simple equipment operation, lower production cost, energy conservation and environmental protection, and easy realization of industrial production, and in addition, the prepared magnesium-aluminum-zinc hydrotalcite can be used for PVC to remarkably improve the thermal stability, initial colorability and transparency of the PVC.

The method for preparing magnesium-aluminum-zinc hydrotalcite according to the schemes 1 and 2 is described in detail below with reference to fig. 1 to 4.

According to an embodiment of the present invention, referring to fig. 1, scheme 1 includes S100 to S400:

s100: filtering the electrolytic waste liquid of the aluminum-air battery to obtain a first filtrate

According to the embodiment of the invention, the method is carried out on the basis of the filtrate obtained by filtering the waste electrolyte after the discharge of the aluminum-air battery as a main aluminum source and the alkaline condition, and the waste electrolyte can be an alkaline electrolyte system comprising potassium hydroxide and sodium hydroxide.

S200: mixing the first filtrate, a magnesium source and a zinc source for reaction to obtain a mixed solution containing hydroxide radical type magnesium-aluminum-zinc hydrotalcite

According to embodiments of the present invention, co-deposition may be employedPrecipitating or hydrothermal reacting magnesium source, zinc source and Al (OH) in the first filtrate (corresponding to the potassium metaaluminate solution in figure 3)₄ ^-The reaction generates hydroxyl type magnesium-aluminum-zinc hydrotalcite to realize Al (OH) in the filtrate₄ ^-And transferring to a solid state, thereby realizing the separation of aluminum and filtrate. It should be noted that the kind of the magnesium source and the zinc source used in the present invention is not particularly limited, and those skilled in the art can select them according to the actual needs, only the requirement that the magnesium source and the zinc source can react with Al (OH)₄ ^-The hydroxide type magnesium aluminum zinc hydrotalcite may be formed by the reaction, for example, the magnesium source may be one or more selected from magnesium hydroxide, magnesium chloride, magnesium oxide, magnesium sulfate, magnesium nitrate and magnesium carbonate, and the zinc source may be one or more selected from zinc hydroxide, zinc chloride, zinc oxide, zinc sulfate, zinc nitrate and zinc carbonate. In addition, the amount of the magnesium source and the zinc source in the present invention is not particularly limited, and those skilled in the art can select the amount according to actual needs, such as the aluminum content in the filtrate and the stoichiometric ratio of the magnesium-aluminum-zinc hydrotalcite, so as to fully utilize the aluminum in the filtrate, and avoid introducing too many impurity ions, and avoid the problem that the regeneration of the electrolytic waste liquid is affected by introducing too many impurity ions.

According to some embodiments of the present invention, when the first filtrate, the magnesium source, and the zinc source are mixed to perform a reaction, the reaction temperature may be 40 to 150 ℃, for example, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, or 140 ℃, and the reaction time may be 2 to 12 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or 11 hours, and the inventors found that, if the reaction temperature is too low or the reaction time is too short, the reaction is incomplete, and sufficient removal of aluminum in the filtrate cannot be achieved, which affects regeneration of the electrolytic waste liquid; if the reaction time is too long, the preparation efficiency is influenced, and the preparation efficiency can be ensured, the full reaction of the aluminum, the magnesium source and the zinc source is facilitated, and the separation of the aluminum and the regeneration of the electrolytic waste liquid are more facilitated by controlling the reaction conditions.

S300: carrying out solid-liquid separation on the mixed solution containing the hydroxyl type magnesium-aluminum-zinc hydrotalcite to obtain hydroxyl type magnesium-aluminum-zinc hydrotalcite and second filtrate

The method and apparatus for performing solid-liquid separation according to the embodiment of the present invention are not particularly limited, and those skilled in the art can select the method according to actual needs, for example, the method of performing solid-liquid separation by vacuum filtration, pressure filtration, centrifugal separation, gravity settling, or the like, and the apparatus such as a vacuum filter or a plate-and-frame filter press can be used for performing solid-liquid separation.

According to some embodiments of the present invention, it is understood with reference to fig. 3 that the second filtrate (corresponding to the filtrate used for electrolyte formulation in fig. 3) may be subjected to alkali supplementation to obtain a regenerated electrolyte for an aluminum air battery. The inventor finds that when the magnesium source and the zinc source are added into the first filtrate for reaction, because the additive is single, excessive impurity ions are not introduced, the filtrate is an alkaline solution comprising potassium hydroxide and sodium hydroxide, and the filtrate can be directly used as a regenerated electrolyte for an aluminum-air battery after alkali supplement, so that the purposes of fully recycling electrolytic waste liquid and reducing the production cost of the aluminum-air battery are achieved. Further, based on the existing aluminum air battery electrolysis waste liquid, a magnesium source and a zinc salt are added for reaction, aluminum is separated out, and OH in filtrate^-The concentration of (A) is usually 1-4 mol/L, the use requirement of the aluminum air battery can be better met after alkali supplement is carried out on the aluminum air battery, and OH in the regenerated electrolyte after alkali supplement is preferably selected^-The concentration of (2) is 5-8 mol/L, and the concentration can be specifically selected according to actual requirements such as the use requirement of the aluminum air battery. Wherein, sodium hydroxide and/or potassium hydroxide can be added into the second filtrate for alkali supplement.

According to further embodiments of the present invention, it can be understood by referring to fig. 3 that the hydroxide type magnesium aluminum zinc hydrotalcite (or filter cake containing hydroxide type magnesium aluminum zinc hydrotalcite) can be washed and dried with water, and the washing water is recycled to step S200 as a reaction medium for the co-precipitation method or hydrothermal method, so that the recycling of water can be further realized.

S400: reacting hydroxyl type magnesium-aluminum-zinc hydrotalcite with a carbon source, and filtering to obtain a third filtrate and magnesium-aluminum-zinc hydrotalcite

According to the embodiment of the invention, carbonate can be further introduced by utilizing a carbon source to provide interlayer anions for the preparation of the magnesium-aluminum-zinc hydrotalcite. It should be noted that the kind of the carbon source in the present invention is not particularly limited, and those skilled in the art can select the carbon source according to actual needs as long as the carbonate can be inserted between the layers of the magnesium aluminum zinc hydrotalcite, and the carbon source may be one or more selected from potassium carbonate, sodium bicarbonate, potassium bicarbonate and carbon dioxide.

According to some embodiments of the present invention, the hydroxide-type magnesium aluminum zinc hydrotalcite and the carbon source are reacted by either hydrothermal synthesis or roasting reduction. When a hydrothermal synthesis method is adopted, the reaction temperature of the hydrothermal synthesis can be 60-200 ℃, for example, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 160 ℃, 180 ℃ or 200 ℃, the reaction time can be 4-15 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours or 14 hours, and the like, and the controlled pH value can be 8-12, for example, 8.5, 9, 9.5, 10, 10.5, 11 or 12, and the inventors find that the crystal form of the finally prepared hydrotalcite is affected by peracid or overbase during the hydrothermal synthesis reaction, so that the crystal form of the formed hydrotalcite is not good, and the better hydrotalcite can be obtained by controlling the pH value of the mixed solution to 8-12; in addition, the temperature of the hydrothermal synthesis reaction is too high or too low, which affects the crystal form structure of the hydrotalcite and thus the thermal stability of the hydrotalcite.

According to some further embodiments of the present invention, when the calcination reduction method is adopted to realize the reaction of the hydroxyl type magnesium aluminum zinc hydrotalcite and the carbon source, the hydroxyl type magnesium aluminum zinc hydrotalcite may be calcined at 400 to 800 ℃ for 3 to 8 hours in advance, and then the calcined product and a solution containing the carbon source are mixed and stirred for 12 to 24 hours, wherein the calcination temperature may be 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, or 750 ℃ and the like, the calcination time may be 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours and the like, the hydroxyl of the hydroxyl type magnesium aluminum zinc hydrotalcite may be sufficiently removed by calcination treatment, so that carbonate is more easily inserted into the interlayer of the magnesium aluminum zinc hydrotalcite, and after the calcination is completed, when the calcined product and the carbon source solution are mixed, carbonate can be inserted into the interlayer structure without adjusting the pH value, so as to obtain the magnesium aluminum zinc hydrotalcite with a better crystal form.

According to still other embodiments of the present invention, it can be understood by referring to fig. 3 that the third filtrate (corresponding to the filtrate obtained after adding carbon source to perform reforming reaction and solid-liquid separation in fig. 3) can be further subjected to evaporation concentration to obtain carbonate or a concentrated solution, wherein the obtained carbonate can include potassium carbonate and/or sodium carbonate; in addition, part or all of the carbonate or the concentrated solution can be recycled in step S400, and the above operation can be adopted to realize the full utilization of the carbon source and avoid the discharge of excessive wastewater.

According to an embodiment of the present invention, referring to FIG. 2, scheme 2 includes S1-S3:

s1: filtering the electrolytic waste liquid of the aluminum-air battery to obtain a fourth filtrate

According to the embodiment of the invention, the method is carried out on the basis of the filtrate obtained by filtering the waste electrolyte after the discharge of the aluminum-air battery as a main aluminum source and the alkaline condition, and the waste electrolyte can be an alkaline electrolyte system comprising potassium hydroxide and sodium hydroxide.

S2: mixing the fourth filtrate, a magnesium source, a zinc source and a carbon source for reaction to obtain a mixed solution containing magnesium-aluminum-zinc hydrotalcite

According to the embodiment of the present invention, the magnesium source, the zinc source, the carbon source and the Al (OH) in the fourth filtrate (corresponding to the potassium metaaluminate-containing solution in FIG. 4) can be co-precipitated or hydrothermally mixed₄Reaction to produce Mg-Al-Zn hydrotalcite to obtain Al (OH) in filtrate₄ ^-And transferring to a solid state to further realize the separation of aluminum and filtrate, wherein the carbon source mainly provides interlayer anions for the preparation of the magnesium-aluminum-zinc hydrotalcite. It should be noted that the kinds of the magnesium source, the zinc source and the carbon source used in the present invention are not particularly limited, and those skilled in the art can select the actual needThe selection is carried out only if the magnesium source, the zinc source and the carbon source can react with Al (OH)₄ ^-The magnesium aluminum zinc hydrotalcite may be prepared by reacting magnesium, aluminum and zinc hydrotalcite, for example, the magnesium source may be one or more selected from magnesium hydroxide, magnesium chloride, magnesium oxide, magnesium sulfate, magnesium nitrate and magnesium carbonate, the zinc source may be one or more selected from zinc hydroxide, zinc chloride, zinc oxide, zinc sulfate, zinc nitrate and zinc carbonate, and the carbon source may be one or more selected from potassium carbonate, sodium bicarbonate, potassium bicarbonate and carbon dioxide. In addition, the amount of the magnesium source, the zinc source and the carbon source used in the present invention is not particularly limited, and those skilled in the art can select the amount according to actual needs, such as the aluminum content in the filtrate and the stoichiometric ratio of the magnesium-aluminum-zinc hydrotalcite, so as to fully utilize the aluminum in the filtrate.

According to some embodiments of the present invention, when the fourth filtrate, the magnesium source, the zinc source, and the carbon source are mixed to perform a reaction, the reaction temperature may be 40 to 150 ℃, for example, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, or 140 ℃, and the reaction time may be 2 to 12 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or 11 hours, and the inventors found that if the reaction temperature is too low or the reaction time is too short, the reaction may be incomplete, and the sufficient removal of aluminum in the filtrate cannot be achieved; if the reaction time is too long, the preparation efficiency is influenced, and the preparation efficiency can be ensured, the full reaction of the aluminum, the magnesium source and the zinc source is facilitated, and the recovery rate of the aluminum is improved by controlling the reaction conditions.

S3: carrying out solid-liquid separation on the mixed liquid containing the Mg-Al-Zn hydrotalcite to obtain a fifth filtrate and the Mg-Al-Zn hydrotalcite

The method and apparatus for performing solid-liquid separation according to the embodiment of the present invention are not particularly limited, and those skilled in the art can select the method according to actual needs, for example, the method of performing solid-liquid separation by vacuum filtration, pressure filtration, centrifugal separation, gravity settling, or the like, and the apparatus such as a vacuum filter or a plate-and-frame filter press can be used for performing solid-liquid separation.

According to some embodiments of the present invention, it can be understood by referring to fig. 4 that the magnesium aluminum zinc hydrotalcite (or the filter cake containing the magnesium aluminum zinc hydrotalcite) can be washed and dried with water, and the washing water is recycled to step S2 as a reaction medium for the co-precipitation method or the hydrothermal method, so that the recycling of water can be further achieved.

According to further embodiments of the present invention, it can be understood by referring to fig. 4 that the fifth filtrate (corresponding to the filtrate obtained by performing solid-liquid separation in fig. 4) can be further subjected to evaporative concentration to obtain carbonate or a concentrated solution, wherein the obtained carbonate can include potassium carbonate and/or sodium carbonate; in addition, part or all of the carbonate or the concentrated solution can be recycled to step S3, and the above operation can be used to achieve full utilization of carbon source and avoid excessive discharge of wastewater.

It should be noted that the specific forms of the magnesium source, the zinc source and the carbon source added in the present invention are not particularly limited, and those skilled in the art can select them according to the actual needs, for example, the three sources may be provided separately in a solid form or separately in a solution form, as long as the reaction requirements can be met.

In summary, the method for preparing magnesium-aluminum-zinc hydrotalcite according to the above embodiment of the present invention may have the following advantages: (a) when the scheme 1 is adopted, the magnesium source and the zinc source are added into the electrolytic waste liquid of the aluminum-air battery to generate the magnesium-aluminum-zinc hydrotalcite, the additive is single, and the recycling of the electrolytic waste liquid of the aluminum-air battery can be realized. (b) The prepared magnesium-aluminum-zinc hydrotalcite has the advantages of low impurity content, easy crystal form control, simple equipment operation, low production cost, energy conservation, environmental protection and easy realization of industrial production. (c) The magnesium-aluminum-zinc hydrotalcite with higher added value is recovered by utilizing the electrolysis waste liquid, so that the production cost of the aluminum-air battery and the preparation cost of the magnesium-aluminum-zinc hydrotalcite are greatly reduced. (d) The third filtrate in the scheme 1 and the fifth filtrate in the scheme 2 can be fully utilized by evaporation and concentration. (e) Provides a new direction for the preparation of the magnesium-aluminum-zinc hydrotalcite and the recycling of the electrolytic waste liquid of the aluminum-air battery. (f) The prepared magnesium-aluminum-zinc hydrotalcite can be used as a heat stabilizer of PVC, and can improve the initial colorability and transparency of PVC while improving the thermal stability of PVC.

In still another aspect of the invention, the invention provides the use of the method for preparing the magnesium-aluminum-zinc hydrotalcite in the recovery of aluminum-air battery electrolysis waste liquid, the production of the magnesium-aluminum-zinc hydrotalcite, and the improvement of PVC thermal stability and initial colorability. Compared with the prior art, the application has the following advantages: can realize the resource utilization of the electrolytic waste liquid of the aluminum-air battery, can reduce the production cost of the aluminum-air battery and the magnesium-aluminum-zinc hydrotalcite, and can obviously improve the initial colorability and the transparency of the PVC on the basis of improving the thermal stability of the PVC. It should be noted that the features and effects described for the above method for preparing magnesium-aluminum-zinc hydrotalcite are also applicable to the application, and are not described in detail herein.

The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Example 1

Filtering filtrate of waste electrolyte obtained after 100L of aluminum air battery is discharged into a 300L reaction kettle, wherein the aluminum content is 102.5g/L, heating and stirring, and when the solution temperature reaches 60 ℃, mixing according to the molar ratio of aluminum, magnesium and zinc of 1: 2.8: 0.2, respectively weighing 42.8kg of magnesium oxide and 6.2kg of zinc oxide, putting the magnesium oxide and the zinc oxide into a reaction kettle, heating and stirring the mixture to enable the reaction temperature to reach 120 ℃, and carrying out constant-temperature hydrothermal reaction for 6 hours; and (3) filtering the reactant by adopting a plate-and-frame filter press under pressure, wherein the concentration of the filtrate is regenerated alkali liquor and is 3.1mol/L, and then supplementing potassium hydroxide or sodium hydroxide in the regenerated alkali liquor to ensure that the concentration of the alkali liquor reaches 6 mol/L. At the temperature of the electrolyte of 60 ℃, the anode is aluminum alloy, the cathode is an air electrode, and the current density is 160mA/cm²Next, the discharge performance of the aluminum-air battery is tested, so that the use requirement of the aluminum-air battery can be well met; washing the filter cake with deionized water to pH 11, transferring the filter cake to a high-temperature reaction kettle, adding a potassium carbonate solution to pH 9, reacting at 180 ℃ for 6h, filtering and washing to neutrality, drying at 80 ℃ for 10h to obtain the magnesium-aluminum hydrotalcite,the filtrate is evaporated and concentrated to obtain potassium carbonate.

Example 2

The aluminum content of the filtered waste electrolyte after 100L of aluminum air battery discharge is 102.5g/L filtrate, 42.8kg of magnesium nitrate and 6.2kg of zinc nitrate are dissolved in 300L deionized water, and 157.2kg of potassium carbonate is dissolved in the deionized water. The three mixed liquids are stirred and dripped into a 500L reaction kettle. After the dropwise addition is finished, carrying out hydrothermal reaction for 8 hours at a constant temperature of 90 ℃; filtering under mechanical pressure, washing until the pH value is 7, and drying at 80 ℃ to obtain the magnesium-aluminum hydrotalcite.

FIG. 5 is an SEM image of the magnesium-aluminum-zinc hydrotalcite prepared in example 1, and it can be seen from the SEM image that the prepared magnesium-aluminum-zinc hydrotalcite has uniform particle size and good overall morphology; FIG. 6 is a TG-DSC curve of the Mg-Al-Zn hydrotalcite prepared in example 1. from the TG curve and the DSC curve in FIG. 6, it can be seen that the Mg-Al-Zn hydrotalcite has significant weight loss and endothermic heat absorption near 250 ℃ during the temperature rise process, which is due to the removal of crystal water between layers of the hydrotalcite in the temperature range; the endothermic peak near 400 ℃ corresponds to the removal of carbonate radicals between hydrotalcite layers, which indicates that the layered structure of hydrotalcite is destroyed.

In summary, the magnesium-aluminum hydrotalcite can be prepared by both methods, and the examples have the following beneficial effects: 1) example 1 magnesium aluminum zinc hydrotalcite can be prepared using a waste electrolyte of an aluminum-air battery, and the battery is tested by recycling the filtrate; 2) the process flow for preparing the magnesium-aluminum-zinc hydrotalcite is short, and the equipment investment is relatively low; 3) the method realizes the recycling of waste resources, has simple preparation process, is energy-saving and environment-friendly, and reduces the cost of the aluminum-air battery.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.