CN115041134B

CN115041134B - Carbonized gel material with lithium adsorption performance and preparation method and application thereof

Info

Publication number: CN115041134B
Application number: CN202210637753.8A
Authority: CN
Inventors: 王敏; 吕肖斐; 王怀有
Original assignee: Qinghai Institute of Salt Lakes Research of CAS
Current assignee: Qinghai Institute of Salt Lakes Research of CAS
Priority date: 2022-06-08
Filing date: 2022-06-08
Publication date: 2023-09-22
Anticipated expiration: 2042-06-08
Also published as: CN115041134A

Abstract

The application discloses a carbonized gel material with lithium adsorption performance, and a preparation method and application thereof. The preparation method of the carbonized gel material with the lithium adsorption performance comprises the following steps: mixing the gel skeleton material with water, and adding a lithium adsorption material to obtain a first mixed solution; dissolving chitosan, sodium carboxymethyl cellulose and calcium chloride in a hydrochloric acid solution to obtain a second mixed solution; the second mixed liquid is taken as a receiving liquid, and the first mixed liquid is dripped into the second mixed liquid to form gel balls; crosslinking the gel balls; freezing the gel ball after the crosslinking treatment at low temperature; and carbonizing the gel balls subjected to low-temperature freezing in a protective atmosphere to obtain the carbonized gel material with lithium adsorption performance. The carbonized gel material with the lithium adsorption performance prepared by the application can keep stable structure in the recovery and desorption processes of lithium ions, and overcomes the characteristic that the gel material is easy to swell in solution to cause the reduction of adsorption capacity.

Description

Carbonized gel material with lithium adsorption performance and preparation method and application thereof

Technical Field

The application belongs to the technical field of adsorbent preparation, and particularly relates to a carbonized gel material with lithium adsorption performance, and a preparation method and application thereof.

Background

The hydrogel is a high polymer material with a three-dimensional network structure, can absorb a large amount of water to swell and is insoluble in water, is often used for adsorbing metal ions because of a simple preparation mode, a certain water-retaining property and a unique network structure, and common hydrogel materials such as calcium alginate, chitosan, polyacrylamide, polyacrylic acid and cellulose gel have obvious ion adsorption performance. Chinese patent CN112876611a discloses a method for preparing a conductive polysaccharide composite hydrogel, wherein the hydrogel is prepared by mixing a polymerizable hydrogen bond donor, a non-polymerizable hydrogen bond donor and a hydrogen bond acceptor in a certain ratio, adding a polysaccharide solid powder, and finally crosslinking to initiate formation of a polymerizable crosslinked polysaccharide eutectic solvent liquid mixture solution. And then the solution is heated to initiate polymerization reaction to prepare the composite hydrogel, and the conductive polysaccharide composite hydrogel has high conductivity and compressive strength and has wide application prospect in the field of flexible electronic materials.

The hydrogel type adsorption material is prepared by mixing inorganic materials with specific adsorption performance into gel precursors, and obtaining solid gel materials with various forms through certain heating, alkali treatment and crosslinking reaction. The preparation method of the adsorbent is simple and convenient in process, the used solvents and medicines have biological safety, environmental pollution is not easy to cause, and the gel has certain adsorption performance, and after the specific metal ion adsorbent powder is combined, metal ions in the solution can be efficiently recovered. However, the gel material has a large defect in the practical use process, for example, chitosan cannot be stably present in an acid solution, most lithium ion adsorbents need to be acidized, the gel material is shaped to have certain requirements on the powder load content, if the load amount is too large, the gel material is difficult to be shaped, and the mechanical stability of the gel material is poor, because the humidity of the environment is easy to dry and shrink or swell, and the gel material is unfavorable for the practical production process of recycling lithium.

For the gel material, the mechanical property can be improved by a composite crosslinking or drying carbonization mode. The crosslinking mode is common, for example, polyacrylamide (PAM) is a linear high molecular polymer, and the mechanical property is poor. Polyvinyl alcohol (PVA) is a water-soluble synthetic polymer, is nontoxic, and is moderately crosslinked after being combined, so that firm microcrystalline crosslinking bonds can be formed, and the mechanical strength of the hydrogel is improved. Chinese patent CN114163657a discloses a preparation of an extrudable (3D printing) hydrogel based on metal dynamic coordination bonds, by compounding natural macromolecular polysaccharide, acrylamide, water-soluble B vitamins and metal cations according to a certain proportion, a modified interpenetrating network system hydrogel is formed, and inherent defects of low mechanical strength, poor self-healing performance and the like of the traditional hydrogel are improved. And the hydrogel can also meet the requirement of 3D printing, and is extruded from the equipment and stacked to form a special shape. Chinese patent CN107418083a discloses a stable and durable polyvinyl chloride material and a preparation method thereof, and the material is subjected to composite modification by chitosan, resin and the like, so that the heat resistance of the polyvinyl chloride is improved, and the service life of the product is prolonged.

For the gel material, freeze drying or high-temperature carbonization can also be used for controlling the morphology structure and the particle size of the material, the particle size of the gel adsorbent prepared by a common physical extrusion mode is too large and needs to be further crushed, water and partial gel frameworks in large gel particles can be removed by high temperature or freeze drying, so that the particle size is reduced, the structure becomes loose and porous, and the structure size is designed by the mode, so that the solid adsorbent particles meeting the actual requirements can be prepared. The freeze drying mode can efficiently form holes and endow gel balls with certain mechanical strength, and Chinese patent CN101401956A discloses a preparation mode of chitosan porous particles, and the prepared chitosan balls are subjected to condensation treatment by using a whole set of equipment and then freeze drying, so that porous chitosan particles with through pore channels can be obtained. Chinese patent CN104084179a discloses a polymer monolithic column, its preparation method and application. The whole column firstly carries out initiation crosslinking on glycidyl methacrylate to obtain jelly emulsion, then carries out low-temperature polymerization to obtain a gel column, and finally adopts a freeze-drying gel technology, so that the prepared whole column has a multi-level pore structure and excellent permeability, and is beneficial to separation of hydrophobic small molecules. However, freeze drying cannot avoid the swelling property of gel materials when meeting water or solvents, and freeze drying equipment has high cost and low working efficiency, and is not beneficial to mass production.

Chinese patent CN111558350a discloses a method for preparing HTO/cellulose aerogel microspheres for extracting lithium from seawater, which comprises adding α -cellulose into an ionic liquid, heating and stirring in an oil bath to obtain a cellulose solution, adding ion sieve HTO powder into the cellulose solution, dripping the HTO/cellulose mixed solution into an ethanol coagulation bath to obtain hydrogel microspheres, and freeze-drying. The HTO/cellulose aerogel microspheres prepared in this way are easy to recycle, have rich pore channel structures, and can enable more lithium adsorption active sites on the HTO to be directly exposed to lithium-containing solution, thereby realizing rapid and efficient adsorption and desorption of lithium.

The stability of the gel material can be improved very quickly through heating and carbonization, and the treatment mode can lead the gel to be pyrolyzed and produce gas, so that the gel can be generally used for preparing carbonized gel with a macroporous structure, has wide application, and can be used for adsorbing materials, medical carriers, nano material carriers and the like. Chinese patent CN107056318A discloses a preparation method of carbon nanotube-carbon aerogel by activating and carbonizing carbon nanotube-polysaccharide sol at high temperature. The material not only has the excellent performance of the carbon nano tube, but also has a special edge structure with adjustable morphology, and has the advantages of large specific surface area, high porosity, uniform pore size, uniform distribution and the like. The method can also be used for preparing lithium adsorption particles, and Chinese patent CN110215896A discloses a porous silicon sphere supported lithium carbide adsorption resin, which is prepared by mixing aluminum hydroxide and silica sol, adding uric acid, nitric acid and the like, uniformly stirring, reacting to obtain aluminum hydroxide/urea formaldehyde resin doped silica gel microspheres, and further sintering the gel microspheres to remove urea formaldehyde resin to obtain the porous silicon sphere supported lithium adsorption resin. The preparation process of the porous silicon sphere supported lithium adsorption resin is simple, the obtained porous silicon sphere supported lithium adsorption resin is spherical, the specific surface area is large, the particle size distribution is uniform, the product performance is stable, and the lithium extraction efficiency is high.

The current granulating mode of the adsorption column filling lithium adsorbent has multiple channels and characteristics, gel material compounding is a promising granulating technology, and the common gel composite adsorbent has the defects of easy swelling, poor thermal stability and poor mechanical stability in the practical application process although the adsorption quantity is high and the preparation process has no pollution to the environment. Some solutions such as freeze drying, carbon nanotube preparation, electrostatic spinning and other technical means can greatly increase the production cost of the adsorbent. In addition, the adsorbent generally needs acid washing and desorption treatment in the adsorption process of lithium ions, but the hydrogel spheres are not modified and have poor thermal stability and acid and alkali resistance.

Disclosure of Invention

The application mainly aims to provide a carbonized gel material with lithium adsorption performance, and a preparation method and application thereof, so as to overcome the defects in the prior art.

In order to achieve the above object, the technical solution adopted in the embodiment of the present application includes:

the embodiment of the application provides a preparation method of a carbonized gel material with lithium adsorption performance, which comprises the following steps:

mixing a gel framework material with water to obtain a hydrogel system, and adding a lithium adsorption material to obtain a first mixed solution, wherein the gel framework material comprises sodium alginate, polyvinyl alcohol and polyacrylic acid;

dissolving chitosan, sodium carboxymethyl cellulose and calcium chloride in a hydrochloric acid solution to obtain a second mixed solution;

the second mixed liquid is taken as a receiving liquid, and the first mixed liquid is dripped into the second mixed liquid to form gel balls;

crosslinking the gel balls;

freezing the gel ball after the cross-linking treatment at low temperature;

and carbonizing the gel balls subjected to low-temperature freezing in a protective atmosphere to obtain the carbonized gel material with lithium adsorption performance.

Further, the content of the sodium alginate in the first mixed solution is 1-5wt%.

Further, the content of the polyacrylic acid in the first mixed solution is 1-5wt%.

Further, the content of the polyvinyl alcohol in the first mixed solution is 0.3-1.5wt%.

Further, the mass ratio of the first mixed solution to the second mixed solution is 1:1-1:5.

Further, the particle size of the gel balls is 1-3mm.

Further, the lithium adsorption material comprises any one or more of layered aluminum hydroxide, a lithium titanium ion sieve and a lithium manganese ion sieve, and preferably comprises layered H ₂ TiO ₃ Spinel type H ₄ Ti ₅ O ₁₂ Any one or a combination of a plurality of the above.

Further, the mass ratio of the lithium adsorption material to the first mixed solution is 10-30:100.

further, the mass ratio of the gel skeleton material to the lithium adsorption material is 1:1-1:18.

Further, the preparation method comprises the following steps: dissolving 10-15wt% of anhydrous calcium chloride by adopting 0.1-0.5mol/L of dilute hydrochloric acid, and adding 0.5-2wt% of chitosan and 1-3wt% of sodium carboxymethyl cellulose after the anhydrous calcium chloride is uniformly dissolved to obtain the second mixed solution.

Further, the preparation method comprises the following steps:

mixing a cross-linking agent, an initiator and an alcohol solvent, heating the obtained mixed solution to 50-60 ℃, and then adding the gel balls for reaction.

Further, the preparation method comprises the following steps: placing the gel balls subjected to the crosslinking treatment into condensate liquid for low-temperature freezing;

wherein the condensate is prepared from ethanol, glycol and glycerin, the ethanol content is 60-90wt%, the glycol content is 5-10wt% and the glycerin content is 10-30wt%.

Further, the low-temperature freezing temperature is-10 ℃ to-20 ℃ and the time is 12h to 48h.

Further, the preparation method comprises the following steps:

placing the gel balls subjected to low-temperature freezing into a reaction chamber, heating the temperature in the reaction chamber to 100-150 ℃ at a first heating rate in protective atmosphere, maintaining for 0.5-1h, then continuously heating to 300-400 ℃ at a second heating rate, maintaining for 3-5h, and performing carbonization treatment; wherein the first heating rate is greater than the second heating rate.

Embodiments of the application alsoProvides the carbonized gel material with lithium adsorption performance prepared by the preparation method, the carbonized gel material with lithium adsorption performance has porous adsorption sites and abundant through porous structures, and the specific surface area is 20-50m ² Per gram, particle size of 400-800 μm。

Further, the loading amount of the carbonized gel material with the lithium adsorption performance to the specific lithium adsorption material is 80-90wt%.

The embodiment of the application also provides a lithium adsorbent, which comprises the carbonized gel material with the lithium adsorption performance.

Compared with the prior art, the application has the following beneficial effects:

(1) The preparation method of the carbonized gel material with lithium adsorption performance utilizes the ternary gel composite lithium adsorption material to prepare the solid particle adsorbent which can be used as an adsorption column filling material and is beneficial to recovery.

(2) The ternary gel is used as a framework supporting material, a lithium adsorption material is compounded, and moderate crosslinking is performed, so that the strength of the gel is enhanced; the hydrogel balls are further carbonized after being pretreated, so that porous particles are formed, the thermal stability of the carbonized gel particles is improved, acid and alkali resistance is realized, and acid washing desorption can be stably performed.

(3) The application can also achieve the purposes of improving the load capacity of the carbonized gel material and keeping the adsorption capacity of lithium, the powder is uniformly wrapped by the gel structure, and after the moisture is removed by carbonization, the adsorption capacity of the carbonized gel material is not reduced compared with that of the powder adsorbent, but is improved to some extent, because the porous carbonized gel has certain adsorption performance.

(4) The carbonized gel material with the lithium adsorption performance prepared by the application has the advantages of porous adsorption sites and large specific surface area, and the time required for the carbonized gel material to reach adsorption equilibrium is 5-8 hours faster than that of the adsorbent powder, which indicates that the carbonized gel material can be used as a high-performance adsorption material for rapidly recovering lithium ions.

(5) The application can further control the morphology and the particle size of the carbonized gel ball by controlling the particle size of the hydrogel ball, so that the specific surface area of the carbonized gel ball is increased, the particle size is maintained at 400-800 mu m, and the carbonized gel ball is suitable for filling an adsorption column.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.

FIG. 1 is a photograph showing the appearance of milky white gel ball in example 1 of the present application.

FIG. 2 is a photograph showing the appearance of the gel sphere TH350-1 in example 1 of the present application.

FIG. 3 is an internal photograph of the gel sphere TH350-1 in example 1 of the present application.

FIG. 4 is a graph comparing the stability in acid of different adsorbents in example 15 of the present application.

FIG. 5 is a graph comparing the adsorption equilibrium of lithium by different adsorbents in example 16 of the present application.

Detailed Description

The application will be more fully understood from the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the present application are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the application, which may be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present application in virtually any appropriately detailed embodiment.

Aiming at the defects that the existing lithium ion adsorbent granulating technology is difficult to achieve loose and porous and poor in stability, the application firstly adopts a physical blending mode to mix the adsorbent powder and the hydrogel, so that the network structure of the gel can uniformly cover the adsorbent powder, and then utilizes the heating carbonization treatment to volatilize moisture in the gel sphere and digest part of the gel structure, thereby achieving the effects of carbonization pore-forming and structure stabilization.

The main purpose of the application is as follows: 1. the gel components are proportionally combined to be used as the matrix material of the adsorbent powder, so that the acid resistance and the alkali resistance of the material can be improved to a certain extent. 2. The optimal technological parameters of the combination of the hydrogel and the adsorbent powder are determined, the stable loading of the powder in the hydrogel structure is ensured, the unfolding of the gel network structure is ensured, and the method is suitable for carbonization pore-forming. 3. Through controlling the carbonization temperature rising condition, a porous sphere particle is prepared, and the gel sphere is ensured not to be mutually adhered, collapse and break during carbonization through pretreatment. 4. Through the particle size control of the hydrogel microsphere, the adsorbent particles with the particle size controlled in the range of 400-800 mu m can be prepared after carbonization and moisture removal, and the method can be suitable for filling an ion exchange column. 5. The carbonized adsorbent ball can maintain the adsorption performance, and the structure is kept stable and is not easy to damage in the acid treatment process.

One aspect of the embodiments of the present application provides a method for preparing a carbonized gel material having lithium adsorption performance, including:

crosslinking the gel balls;

freezing the gel ball after the cross-linking treatment at low temperature;

According to the hydrogel, the stability of the hydrogel can be improved only by certain cross-linking, solidification and carbonization pretreatment, wherein cellulose and chitosan in the receiving liquid can play a role in wrapping the outer surface of the gel layer in the forming process of the hydrogel ball, and the effect is better when the total content of the chitosan and the cellulose is controlled to be 1-4wt% of the receiving liquid.

In some preferred embodiments, the sodium alginate is present in the first mixed liquor in an amount of 1-5wt%.

In some preferred embodiments, the polyacrylic acid is present in the first mixed liquor in an amount of 1 to 5wt%.

In some preferred embodiments, the polyvinyl alcohol is present in the first mixed liquor in an amount of 0.3 to 1.5wt%.

In some preferred embodiments, the mass ratio of the first mixed liquor to the second mixed liquor is 1:1-1:5.

In some preferred embodiments, the gel spheres have a particle size of 1-3mm.

In some preferred embodiments, the lithium adsorption material may include any one or a combination of a plurality of layered aluminum hydroxide, lithium titanium ion sieve, lithium manganese ion sieve, etc., but is not limited thereto.

In the embodiment of the application, the specific lithium adsorption material comprises lithium titanium ion sieve, lithium manganese ion sieve, layered aluminum hydroxide and other powder, the weight ratio of the gel skeleton material to the adsorbent powder is in the range of 1:1-1:18, so that the water content of the gel ball is not excessive, and the gel ball is not easy to collapse and crack after carbonization.

In some more preferred embodiments, the lithium-adsorbing material preferably comprises layered H ₂ TiO ₃ Spinel type H ₄ Ti ₅ O ₁₂ Any one or a combination of a plurality of the above.

In some preferred embodiments, the mass ratio of the lithium adsorption material to the first mixed solution is 10-30:100.

in some preferred embodiments, the mass ratio of the gel matrix material to the lithium adsorbent material is from 1:1 to 1:18.

In some preferred embodiments, the preparation method comprises: dissolving 10-15wt% of anhydrous calcium chloride by adopting 0.1-0.5mol/L of dilute hydrochloric acid, and adding 0.5-2wt% of chitosan and 1-3wt% of sodium carboxymethyl cellulose after the anhydrous calcium chloride is uniformly dissolved to obtain the second mixed solution.

In some preferred embodiments, the preparation method comprises:

mixing a cross-linking agent, an initiator and an alcohol solvent, heating the obtained mixed solution to 50-60 ℃, and then adding the gel balls for reaction;

preferably, the initiator comprises potassium persulfate and/or ammonium persulfate, and the initiator content is 0.5-1.6wt% of the weight of the gel sphere.

In some preferred embodiments, the crosslinker comprises N, N-methylenebisacrylamide and the crosslinker content is 8-15wt% based on the weight of the gel beads.

In some preferred embodiments, the alcohol solvent comprises isopropanol and the mass ratio of alcohol solvent to gel spheres is from 2 to 5:1.

in some preferred embodiments, the preparation method comprises: placing the gel balls subjected to the crosslinking treatment into condensate liquid for low-temperature freezing;

In some more preferred embodiments, the low temperature freezing is at a temperature of-10 ℃ to-20 ℃ for a period of 12 hours to 48 hours.

In some preferred embodiments, the preparation method comprises:

In some more preferred embodiments, the first ramp rate is from 5 to 10 ℃/min.

In some more preferred embodiments, the second ramp rate is 2-5 ℃/min.

In some more specific embodiments, the preparation and performance testing steps of the carbonized gel material with lithium adsorption performance (i.e. carbonized gel spheres) of the present application include:

(1) Dissolving sodium alginate, polyvinyl alcohol and polyacrylic acid powder in water, stirring, slowly adding lithium adsorbent powder, stirring and dispersing uniformly to prepare solution A. Chitosan, sodium carboxymethyl cellulose and anhydrous calcium chloride are dissolved in hydrochloric acid solution to prepare solution B.

(2) A hollow hard tube with a certain caliber (1-3 mm) is prepared, the hollow tube is connected with a peristaltic pump, the hollow tube is vertically placed by a clamp, the solution A slowly drops from the hollow tube after being pumped from the peristaltic pump, and the solution B is placed below the hollow tube to be received, so that a milky white gel ball with the particle size of 1-3mm is formed.

(3) Adding a crosslinking initiator into isopropanol, stirring and dissolving, heating the solution to 50-60 ℃ in a water bath, adding the gel balls prepared in the step (2), continuously stirring, reacting for a certain time, changing the gel balls into light yellow, flushing the gel balls with deionized water for several times, and filtering the yellow gel balls for later use.

(4) Pretreatment is carried out before carbonization and heating: the condensate is prepared, the gel balls are placed in the condensate and stored for a certain time at a low temperature, so that the gel balls can be pretreated to ensure that the particles are not bonded, ice crystals are formed in the hydrogel after low-temperature freezing, and pores are easier to generate during carbonization.

(5) Placing the gel balls in the step (4) in a crucible, and performing inert gas protection on a tubular reaction furnace, wherein the temperature is firstly quickly raised to 100-150 ℃, and then slowly raised to 300-400 ℃ after a period of time, and a certain period of time is maintained. The carbonized gel balls are dry porous particles with reduced particle size and are washed with deionized water for a plurality of times, and then acid resistance detection experiments and adsorption experiments are carried out.

The maintenance time is 0.5-1h at 100-150 ℃ and 3-5h at 300-400 ℃, the gel skeleton is completely digested due to the overlong time, and the insufficient water removal and the incomplete pore canal are caused due to the overlong time.

The acid resistance detection is to stand the carbonized gel ball in 1mol/L hydrochloric acid solution, take out and dry after a period of time, weigh and calculate the weight loss.

The adsorption experiment is to put a certain mass of carbonized gel balls into a self-made lithium-containing solution, shake the solution in water bath for 12-24 hours, and detect and calculate the equilibrium adsorption capacity of the carbonized gel balls.

Another aspect of the embodiment of the application provides the carbonized gel material with lithium adsorption performance prepared by the preparation method, wherein the carbonized gel material with lithium adsorption performance has porous adsorption sites and a rich and through porous structure, and the specific surface area is 20-50m ² Per gram, particle size of 400-800 μm。

In some preferred embodiments, the loading of the carbonized gel material with lithium adsorption properties to the specific lithium adsorption material is 80-90wt%.

In another aspect, the embodiment of the application also provides a lithium adsorbent, which comprises the carbonized gel material with the lithium adsorption performance.

In the specific implementation process, the following points are particularly important:

1. in the application, the cross-linking initiation of the ternary gel-lithium ion adsorbent composite sphere is a key stage, and the gel skeleton can be more stable and the adsorbent powder is more uniformly wrapped by carrying out certain heating cross-linking reaction on the ternary gel.

2. The carbonization pretreatment stage is extremely important, after condensate is prepared according to a certain proportion, gel particles can be independently dispersed in the condensate, after the condensate is stored for a period of time at a low temperature, the gel balls are frozen and firm, a plurality of fine ice crystals are formed in the gel balls, rapid sublimation during heating treatment is facilitated, channels are formed, and the channels are mutually communicated, so that the specific surface area of the gel balls can be greatly improved.

3. In the carbonization temperature rising process, a certain temperature interval and a certain temperature rising speed are controlled, so that the sphere can be ensured to form a porous structure and is complete, the carbonization temperature is 300-400 ℃ and the effect is best, the gel skeleton part is digested, the ice crystals are removed, and a through pore canal is formed inside the gel sphere.

The carbonized gel balls are dry porous particles with reduced particle size and are washed with deionized water for a plurality of times, and then acid resistance detection experiments and adsorption experiments are carried out.

In the specific implementation process, the acid resistance detection is to stand the carbonized gel ball in 1mol/L hydrochloric acid solution, take out and dry the gel ball after a period of time, weigh the gel ball and calculate the weight loss of the gel ball.

The adsorption experiment is to put a certain mass of carbonized gel ball into self-made lithium-containing solution, shake the solution in water bath for 12-24h, and detect and calculate the equilibrium adsorption capacity.

Example 1

(1) 1g of sodium alginate, 1g of polyvinyl alcohol and 0.5g of polyacrylic acid powder are dissolved in 97.5g of water, stirred and slowly added with 10g of lithium adsorbent H ₂ TiO ₃ The powder is uniformly stirred and dispersed to prepare a first mixed solution, namely a feed solution; 2g of chitosan, 6g of sodium carboxymethyl cellulose and 30g of anhydrous calcium chloride are dissolved in 300g of hydrochloric acid solution, wherein the concentration of hydrochloric acid is 0.5mol/L, so as to prepare a second mixed solution, namely a receiving solution.

(2) A hollow tube with the caliber of 1.5mm is connected with a peristaltic pump, the hollow tube is vertically arranged, the feed liquid slowly drops from the hollow tube after being pumped from the peristaltic pump, and the receiving liquid is arranged below the hollow tube to be received, so that a milky white gel ball with the particle size of 1.3-1.5 mm is formed, and the milky white gel ball is shown in the attached figure 1.

(3) Adding 1.5g of potassium persulfate and 20g of N, N-methylene bisacrylamide into 300g of isopropanol, stirring and dissolving, heating the solution to 60 ℃ in a water bath, adding the milky white gel ball prepared in the step (2), continuously stirring, reacting for 12h, and filtering the yellow gel ball for later use.

(4) 180g of ethanol, 30g of ethylene glycol and 90g of glycerol are mixed into condensate, the yellow gel balls obtained in the step (3) are placed in the condensate, and the condensate is taken out after being placed at the temperature of minus 20 ℃ for 24 hours, and the frozen gel balls are obtained after filtration.

(5) And (3) placing the gel balls filtered in the step (4) in a tubular reaction furnace through a crucible for nitrogen protection, firstly raising the temperature in the reaction furnace from room temperature to 150 ℃ at a speed of 10 ℃/min, then preserving heat for 1h, raising the temperature in the furnace from 150 ℃ to 350 ℃ at a speed of 5 ℃/min, preserving heat for 4h at 350 ℃, and then reducing the temperature. The gel balls after high-temperature carbonization are taken out, washed and filtered by deionized water for three times, and stored for standby, and finally the prepared gel balls are named as TH350-1, the particle size after carbonization is 600-800 mu m, the gel balls have abundant through hole-shaped structures, the detailed figures are shown in fig. 2 and 3, and the loading amounts of adsorbent powder before and after carbonization are shown in table 1.

Example 2

This embodiment differs from embodiment 1 in that: step (1) 2g of sodium alginate, 1g of polyvinyl alcohol and 0.3g of polyacrylic acid powder are dissolved in 96.7g of water, stirred and slowly added with 25g of lithium adsorbent H ₂ TiO ₃ And (3) stirring and dispersing the powder uniformly to prepare a first mixed solution. The hydrogel spheres with the adsorbent powder accounting for 20 weight percent are prepared. The gel ball after carbonization was named TH350-2. The loading of the adsorbent powder before and after carbonization is shown in table 1.

Example 3

This embodiment differs from embodiment 1 in that: step (1) 1g sodium alginate, 5g polyvinyl alcohol, 1.5g polyacrylic acid powder were dissolved in 92.5g water, stirred and slowly added with 43g lithium adsorbent H ₂ TiO ₃ After the powder was uniformly stirred and dispersed, a first mixed solution was prepared, and the rest of the steps were the same as in example 1. The hydrogel spheres with the adsorbent powder accounting for 30 weight percent are prepared. The gel ball after carbonization was named TH350-3. The loading of the adsorbent powder before and after carbonization is shown in table 1.

Example 4

This embodiment differs from embodiment 1 in that: step (1) 1.5g sodium alginate, 1g polyvinyl alcohol, 0.5g polyacrylic acid powder were dissolved in 97g water, stirred and slowly added with 43g lithium adsorbent H ₂ TiO ₃ After the powder was uniformly stirred and dispersed, a first mixed solution was prepared, and the rest of the steps were the same as in example 1. The hydrogel with the adsorbent powder accounting for 30 weight percent is preparedA ball. The gel ball after carbonization was named TH350-4. The loading of the adsorbent powder before and after carbonization is shown in table 1.

Example 5

The other steps are the same as in example 1, but the temperature raising process in step (5) is to raise the temperature from room temperature to 150 ℃, then keep the temperature for 1h, then raise the temperature in the furnace from 150 ℃ to 400 ℃ at a speed of 5 ℃/min, and keep the temperature for 2h at 400 ℃, the prepared gel balls are TH400-1, the particle size after carbonization is 600 μm-700 μm, and the load of the adsorbent powder before and after carbonization is shown in Table 1.

Example 6

The other steps are the same as in example 1, but the temperature raising process in step (5) is to raise the temperature from room temperature to 150 ℃, then keep the temperature for 1h, then raise the temperature in the furnace from 150 ℃ to 300 ℃ at a speed of 5 ℃/min, and keep the temperature for 5h at 300 ℃, the prepared gel balls are TH300-1, the particle size after carbonization is 600 μm-700 μm, and the load of the adsorbent powder before and after carbonization is shown in Table 1.

TABLE 1 examples 1-6 various charred gel particle sizes and related parameters

Sample ID	Carbonization dewatering amount	Load of adsorbent powder before carbonization	Load of adsorbent powder after carbonization
				TH350-1	85.1％	10％	61％
TH350-2	76.4％	20％	85％
				TH350-3	62.3％	30％	80％
TH350-4	66.5％	30％	90％
				TH300-1	82.9.％	10％	53％
TH400-1	88.6％	10％	80％

As shown in the table above, the carbonization dewatering can effectively improve the proportion of the adsorbent powder in the solid adsorbent particles, the maximum content of the adsorbent powder in the hydrogel balls is only 30wt% before carbonization treatment, but after dewatering, the specific gravity of the adsorbent powder in the particles can be improved to 53-90wt%, so that the optimal adsorption effect can be exerted. In addition, different carbonization temperatures have a certain influence on the dehydration effect, for example, the highest carbonization temperature of TH300-1 is 300 ℃, dehydration is insufficient, certain moisture is still kept in the final microsphere, the carbonized adsorbent powder accounts for 53wt%, the highest carbonization temperature of TH350-1 is 350 ℃, the carbonized adsorbent powder accounts for 61wt%, the highest carbonization temperature of TH400-1 is 350 ℃, and the carbonized adsorbent powder accounts for 80wt%. The higher the temperature, the more moisture is removed and the corresponding adsorbent powder fraction will also increase.

In addition, the loading of the carbonized adsorbent powder, such as TH350-2, can be improved by adjusting the proportion of the gel component and the adding amount of the adsorbent powder, wherein the content of the adsorbent powder before carbonization is 20wt%, the content of the gel component is 3wt%, and the loading of the adsorbent powder after dehydration and carbonization can reach 85wt%. The content of the adsorbent powder before carbonization of TH350-3 and TH350-4 is 30wt%, but under the same carbonization treatment condition, the load of the adsorbent powder of TH350-4 can be increased to 90wt%, and the load of the adsorbent powder of TH350-4 is only 85wt%, because the content of the gel component in the preparation process of TH350-4 is only 2wt%, and the content of the gel component in the preparation process of TH350-3 is up to 5.2wt%, which indicates that the content of the gel component can be properly reduced on the premise of ensuring that the hydrogel spheres can be molded and the adsorbent powder is wrapped, so that the proportion of the adsorbent powder is increased, and the aim of improving the adsorption effect is fulfilled.

Example 7

This embodiment differs from embodiment 1 in that: the diameter of the hollow tube in the step (2) is 1mm, the particle size of the gel balls obtained by dripping is 1.0mm-1.2mm, and the rest steps are the same as those in the example 1, and the particle size after carbonization is 400 mu m-500 mu m.

Example 8

This embodiment differs from embodiment 1 in that: the diameter of the hollow tube in the step (2) is 2mm, the particle size of the gel balls obtained by dripping is 1.75mm-1.8mm, and the rest steps are the same as those in the example 1, and the particle size after carbonization is 570 mu m-710 mu m.

Example 9

This embodiment differs from embodiment 1 in that: the diameter of the hollow tube in the step (2) is 2.5mm, the particle size of the gel balls obtained by dripping is 2.4-2.6mm, and the rest steps are the same as those in the example 1, and the particle size after carbonization is 600-750 mu m.

Example 10

This embodiment differs from embodiment 1 in that: the diameter of the hollow tube in the step (2) is 3mm, the particle size of the gel balls obtained by dripping is 2.5-2.8mm, and the rest steps are the same as those in the example 1, and the particle size after carbonization is 700-800 mu m.

Example 11

This embodiment differs from embodiment 1 in that: in step (3), 0.55g of potassium persulfate was added to 300g of isopropanol, and 8.8g of N, N-methylenebisacrylamide as a crosslinking agent was added, and the other steps were the same as in example 1. The gel ball obtained in this way has moderate crosslinking degree, can keep basic stable structure after carbonization, is loose and porous, and has a specific surface area of 49.1m ² /g。

Example 12

This embodiment differs from embodiment 1 in that: 1.76g of potassium persulfate was added to 300g of isopropanol in step (3), and 16.5g of N, N-methylenebisacrylamide as a crosslinking agent was added thereto, and the other steps were the same as in example 1. The gel spheres thus obtained had a higher degree of crosslinking and a stable charring structure, but the pore structure was less distributed than the particles of example 1, and the specific surface area was lower, only 20m ² /g。

Example 13

This embodiment differs from embodiment 1 in that: the condensed liquid in the step (4) consists of 240g of ethanol, 15g of ethylene glycol and 45g of glycerin, and the yellow gel balls are stored in the condensed liquid, and the temperature condition is set to be minus 20 ℃ for 12 hours. The rest of the procedure is the same as in example 1. Although the freezing time is short, the carbonization and dehydration effects are not affected.

Example 14

This embodiment differs from embodiment 1 in that: the condensed liquid in the step (4) is composed of 210g of ethanol, 30g of ethylene glycol and 60g of glycerin, and the yellow gel balls are stored in the condensed liquid at the temperature of-10 ℃ for 48 hours. The rest of the procedure is the same as in example 1. Although the freezing temperature is higher, the formation of ice crystals and the carbonization pore-forming effect are not affected due to the longer time.

Example 15

The three carbonized gel balls TH300-1, TH350-1 and TH400-1 are respectively taken 2g and put into a hydrochloric acid solution of 300g and 1mol/L, and after 7d, 15d, 30d and 60d storage, the dissolution loss conditions of the gel balls are compared, and the weight loss is found to be less than 0.2%, as shown in figure 4, the carbonized gel balls can exist in acid liquid stably, and the adsorbent is suitable for acid washing and recycling.

Example 16

In example 4, the amount of the lithium adsorbent powder added in step (1) was 16g, the rest was the same as in example 4, the final gel pellet was TH400-2, when the lithium adsorbent powder in step (1) was 22.5g, the rest was the same as in example 4, the final gel pellet was TH400-3, the lithium ion adsorbent powders used in TH400-1, TH400-2, TH400-3 and the gel pellet were used as adsorbents, after all the adsorbents were subjected to acid stripping treatment, the elution amount of lithium ions was tested, and then an adsorption experiment was performed, in which a solution having a lithium ion concentration of 1.0g/L was prepared using lithium chloride, then 2g of the adsorbent was added to a conical flask, and then 100g of lithium chloride solution was added, and after 12 hours of water bath shaking, the lithium ion concentration in the solution was detected, and the equilibrium adsorption amount was calculated. As a result, it was found that the adsorption capacity of the adsorbent particles TH400-3 at a high loading could be 15mg/g, while the powder material H was used ₂ Ti0 ₃ The adsorption capacity is 13mg/g, and the dynamic experiment results prove that as shown in the figure 5, TH400-1, TH400-2 and TH400-3 need 3-4 hours to reach adsorption equilibrium, and H ₂ Ti0 ₃ It takes 7-8 hours to reach adsorption equilibrium.

In addition, the inventors have conducted experiments with other materials, process operations, and process conditions as described in this specification with reference to the foregoing examples, and have all obtained desirable results.

While the application has been described with reference to an illustrative embodiment, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the application. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the application without departing from the scope thereof. Therefore, it is intended that the application not be limited to the particular embodiment disclosed for carrying out this application, but that the application will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.

Claims

1. The preparation method of the carbonized gel material with the lithium adsorption performance is characterized by comprising the following steps of:

mixing a gel framework material with water to obtain a hydrogel system, and adding a lithium adsorption material to obtain a first mixed solution, wherein the gel framework material comprises sodium alginate, polyvinyl alcohol and polyacrylic acid, the content of the sodium alginate in the first mixed solution is 1-5wt%, the content of the polyacrylic acid in the hydrogel system is 1-5wt%, and the content of the polyvinyl alcohol in the hydrogel system is 0.3-1.5wt%; the lithium adsorption material comprises any one or a combination of a plurality of layered aluminum hydroxide, a lithium titanium ion sieve and a lithium manganese ion sieve, the mass ratio of the gel framework material to the lithium adsorption material is 1:1-1:18, and the mass ratio of the lithium adsorption material to the first mixed solution is 10-30:100;

dissolving 10-15wt% of anhydrous calcium chloride by adopting 0.1-0.5mol/L dilute hydrochloric acid, and adding 0.5-2wt% of chitosan and 1-3wt% of sodium carboxymethyl cellulose after the anhydrous calcium chloride is uniformly dissolved to obtain a second mixed solution;

the second mixed liquid is taken as a receiving liquid, the first mixed liquid is dripped into the second mixed liquid to form gel balls, and the mass ratio of the first mixed liquid to the second mixed liquid is 1:1-1:5;

mixing a cross-linking agent, an initiator and an alcohol solvent, heating the obtained mixed solution to 50-60 ℃, and then adding the gel balls for cross-linking treatment, wherein the initiator is potassium persulfate and/or ammonium persulfate, and the content of the initiator is 0.5-1.6wt% of the weight of the gel balls; the cross-linking agent is N, N-methylene bisacrylamide, and the content of the cross-linking agent is 8-15wt% of the weight of the gel ball; the alcohol solvent is isopropanol, and the mass ratio of the alcohol solvent to the gel balls is 2-5:1, a step of;

freezing the gel balls subjected to the crosslinking treatment at a low temperature in condensate, wherein the condensate is prepared from ethanol, glycol and glycerin, the ethanol content is 60-90wt%, the glycol content is 5-10wt%, the glycerin content is 10-30wt%, and the total content of the ethanol, the glycol and the glycerin is 100wt%;

placing the gel balls subjected to low-temperature freezing in a reaction chamber, heating the temperature in the reaction chamber to 100-150 ℃ at a first heating rate in protective atmosphere, maintaining for 0.5-1h, then continuously heating to 300-400 ℃ at a second heating rate, maintaining for 3-5h, and carbonizing to obtain a carbonized gel material with lithium adsorption performance; wherein the first heating rate is greater than the second heating rate.

2. The method of manufacturing according to claim 1, characterized in that: the particle size of the gel ball is 1-3mm.

3. The method of manufacturing according to claim 1, characterized in that: the low-temperature freezing temperature is-10 ℃ to-20 ℃ and the time is 12h to 48h.

4. The method of manufacturing according to claim 1, characterized in that: the first heating rate is 5-10 ℃/min, and the second heating rate is 2-5 ℃/min.

5. A carbonized gel material with lithium adsorption property prepared by the preparation method of any one of claims 1 to 4, characterized in that: the carbonized gel material with lithium adsorption performance has porous adsorption sites and abundant and through porous structures, and the specific surface area is 20-50m ² /g, particle size of 400-800 μm; the loading capacity of the carbonized gel material with the lithium adsorption performance on the specific lithium adsorption material is 80-90wt%.

6. A lithium adsorbent comprising the carbonized gel material with lithium adsorption property of claim 5.