CN115041134A

CN115041134A - Carbonized gel material with lithium adsorption performance and preparation method and application thereof

Info

Publication number: CN115041134A
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: 2022-09-13
Anticipated expiration: 2042-06-08
Also published as: CN115041134B

Abstract

The invention 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 lithium adsorption performance comprises the following steps: mixing the gel framework material with water, and adding a lithium adsorption material to obtain a first mixed solution; dissolving chitosan, sodium carboxymethylcellulose and calcium chloride in a hydrochloric acid solution to obtain a second mixed solution; dripping the first mixed solution into the second mixed solution by taking the second mixed solution as a receiving solution to form gel balls; performing cross-linking treatment on the gel spheres; freezing the gel balls subjected to crosslinking treatment at low temperature; and carbonizing the gel balls frozen at low temperature in a protective atmosphere to obtain the carbonized gel material with lithium adsorption performance. The carbonized gel material with lithium adsorption performance prepared by the invention 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 the adsorption capacity.

Description

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

Technical Field

The invention 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 molecular material with a three-dimensional network structure, can absorb a large amount of water to swell and is insoluble in water, the hydrogel is usually used for adsorbing metal ions because of a simple preparation method, certain water retention and a unique network structure, common hydrogel materials such as calcium alginate, chitosan, polyacrylamide, polyacrylic acid and cellulose gel have obvious ion adsorption performance, the gel material has certain affinity performance to inorganic substances, and can be used for preparing inorganic-gel composite materials through load modification and can be used in various fields such as optics, electrics, medicine and the like. Chinese patent CN112876611A discloses a preparation method of conductive polysaccharide composite hydrogel, which is prepared by mixing a polymerizable hydrogen bond donor, a non-polymerizable hydrogen bond donor and a hydrogen bond acceptor according to a certain proportion, then adding polysaccharide solid powder, and finally carrying out crosslinking to initiate the formation of a polymerizable crosslinked polysaccharide eutectic solvent liquid mixture solution. And heating the solution to initiate polymerization reaction to prepare the composite hydrogel, wherein 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 in a gel precursor, and performing certain heating, alkali treatment and crosslinking reaction to obtain solid gel materials in various forms. The preparation method of the adsorbent is simple and convenient in process, the used solvent and medicine have biological safety, the environmental pollution is not easy to cause, and the gel has certain adsorption performance, and can efficiently recover metal ions in the solution after being combined with the specific metal ion adsorbent powder. However, such gel materials have major defects in the actual use process, for example, chitosan cannot be stably present in an acid solution, most lithium ion adsorbents require acidification treatment, gel material forming has certain requirements on the content of powder load, if the load is too large, the gel material is difficult to form, and secondly, the hydrogel material has poor mechanical stability, because the humidity of the environment is easy to dry and shrink or swell, and is not beneficial to the actual production process of lithium recovery.

For such gel-like materials, mechanical properties can be generally improved by complex crosslinking or dry carbonization. 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 non-toxic, and can form firm microcrystalline cross-linked bonds by moderate cross-linking after the polyvinyl alcohol and the PVA are combined, so that the mechanical strength of the hydrogel is improved. Chinese patent CN114163657A discloses a preparation method of an extrudable (3D printing) hydrogel based on metal dynamic coordination bonds, which is characterized in that natural macromolecular polysaccharide, acrylamide, water-soluble B vitamins and metal cations are compounded according to a certain proportion to form a modified interpenetrating network system hydrogel, so that the inherent defects of low mechanical strength, poor self-healing performance and the like of the traditional hydrogel are improved. And the hydrogel can meet the requirements of 3D printing, and is extruded from 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 compositely modified 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.

The gel material can be subjected to freeze drying or high-temperature carbonization, the shape structure and the particle size of the material can also be controlled, the gel adsorbent prepared by a general physical extrusion mode has an overlarge particle size and needs to be further crushed, water in large gel particles and a part of gel frameworks can be removed by high-temperature or freeze drying, so that the particle size is reduced, the structure becomes loose and porous, and the solid adsorbent particles meeting the actual requirements can be prepared by designing the structure size in such a way. The method of freeze drying can efficiently form pores and endow the gel spheres with certain mechanical strength, and Chinese patent CN101401956A discloses a preparation method of chitosan porous particles. Chinese patent CN104084179A discloses a polymer monolithic column and a preparation method and application thereof. The monolithic column firstly carries out initiation crosslinking on glycidyl methacrylate to obtain jelly-like emulsion, then carries out low-temperature polymerization to obtain a gel column, and finally adopts a freeze-drying gel technology, so that the prepared monolithic column has a multi-stage pore-size structure and excellent permeability and is beneficial to separation of hydrophobic micromolecules. However, freeze-drying cannot avoid the characteristic that the gel material swells when meeting water or a solvent, and freeze-drying equipment is high in manufacturing cost and low in working efficiency, so that large-scale production is not facilitated.

Chinese patent CN111558350A discloses a preparation method of HTO/cellulose aerogel microspheres for seawater lithium extraction, which comprises the steps of adding alpha-cellulose into ionic liquid, heating and stirring in an oil bath to obtain a cellulose solution, then 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 finally carrying out freeze drying. The prepared HTO/cellulose aerogel microspheres are easy to recover, have rich pore channel structures, can enable more active sites on HTO to be adsorbed by lithium to be directly exposed in a lithium-containing solution, and realize rapid and efficient adsorption and desorption of lithium.

The stability of the gel material can be improved very fast by heating and carbonization, and the treatment mode can cause the gel to generate gas by pyrolysis, so the gel material 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 has the excellent performance of the carbon nano tube, has a special edge structure with adjustable appearance, 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 ball supported lithium carbide adsorption resin, wherein the adsorption resin is prepared by mixing aluminum hydroxide and silica sol, adding uric acid, nitric acid and the like, uniformly stirring, reacting to obtain silica gel microspheres doped with aluminum hydroxide/urea-formaldehyde resin, and further sintering the gel microspheres to remove the urea-formaldehyde resin, thereby obtaining the porous silicon ball supported lithium adsorption resin. The preparation process of the porous silicon ball supported lithium adsorption resin is simple, and the obtained porous silicon ball supported lithium adsorption resin is spherical, large in specific surface area, uniform in particle size distribution, stable in product performance and high in lithium extraction efficiency.

The granulation mode of the current adsorption column filling lithium adsorbent is multi-channel and multi-characteristic, gel material compounding is a promising granulation technology, and although the general gel composite adsorbent has high adsorption capacity and no pollution to the environment in the preparation process, the defects of easy swelling, poor thermal stability and poor mechanical stability exist in the practical application process. 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, in the adsorption process of lithium ions, the adsorbent generally needs acid-washing desorption treatment, but the hydrogel ball is not modified, has poor thermal stability and is not acid-base resistant.

Disclosure of Invention

The invention 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 aforementioned object, the embodiment of the present invention adopts a technical solution that includes:

the embodiment of the invention 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 carboxymethylcellulose and calcium chloride in a hydrochloric acid solution to obtain a second mixed solution;

dripping the first mixed solution into the second mixed solution by taking the second mixed solution as a receiving solution to form gel balls;

performing cross-linking treatment on the gel spheres;

freezing the gel balls subjected to crosslinking treatment at low temperature;

and carbonizing the gel balls frozen at low temperature 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 1-5 wt%.

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

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

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 ball is 1-3 mm.

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

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

furthermore, the mass ratio of the gel framework material to the lithium adsorbing material is 1:1-1: 18.

Further, the preparation method comprises the following steps: dissolving 10-15 wt% of anhydrous calcium chloride by using 0.1-0.5mol/L of dilute hydrochloric acid, and after uniformly dissolving, adding 0.5-2 wt% of chitosan and 1-3 wt% of sodium carboxymethylcellulose 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 crosslinking treatment in a condensate for low-temperature freezing;

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

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

Further, the preparation method comprises the following steps:

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

The embodiment of the invention also provides the carbonized gel material with lithium adsorption performance prepared by the preparation method, and the carbonized gel material with lithium adsorption performance has porous adsorption sites, abundant through porous structures and a specific surface area of 20-50m ² (g) a particle size of 400-。

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

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

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

(1) the preparation method of the carbonized gel material with the 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) According to the invention, ternary gel is used as a framework support material, a lithium adsorption material is compounded, and then proper crosslinking is carried out, so that the strength of the gel is enhanced; the hydrogel spheres are further pretreated and then carbonized to form porous particles, and the carbonized gel particles have improved thermal stability, acid and alkali resistance and can be stably subjected to acid washing and desorption.

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

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

(5) The invention 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 is increased, the particle size is maintained at 400-800 mu m, and the method is suitable for filling the 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 needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

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

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

Fig. 3 is a photograph of the inside of the gel ball 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 present invention 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 invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can 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 invention in virtually any appropriately detailed embodiment.

Aiming at the defects that the existing lithium ion adsorbent granulation technology is difficult to achieve looseness, porosity and poor stability, the invention 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 water in the gel ball and clear up part of the gel structure, thereby achieving the effects of carbonizing, forming pores and stabilizing the structure.

The main purposes of the invention are: 1. several gel components are combined in proportion to be used as a base 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 process parameters for compounding the hydrogel and the adsorbent powder are determined, the powder can be stably loaded in a hydrogel structure, and the network structure of the gel is ensured to be stretched, so that the method is suitable for carbonization and pore forming. 3. The porous spherical particles are prepared by controlling the temperature rising condition of carbonization, and the gel balls are prevented from being adhered, collapsed and broken during carbonization through pretreatment. 4. By controlling the particle size of the hydrogel microspheres, after carbonization and moisture removal, the adsorbent particles with the particle size controlled within the range of 400-800 mu m can be prepared, and the method can be suitable for filling ion exchange columns. 5. The carbonized adsorbent ball can maintain the adsorption performance, and keep the structure stable and not easy to damage in the acid treatment process.

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

dripping the first mixed solution into the second mixed solution by taking the second mixed solution as a receiving solution to form gel spheres;

performing crosslinking treatment on the gel spheres;

freezing the gel balls subjected to crosslinking treatment at low temperature;

In the embodiment of the invention, the stability of the hydrogel can be improved only by carrying out certain crosslinking curing and carbonization pretreatment on the hydrogel, wherein cellulose and chitosan in the receiving liquid can play a role in wrapping the outer surface of a gel layer in the hydrogel ball forming process, and the effect is better when the total content of the chitosan and the cellulose is controlled to be 1-4 wt% of the receiving liquid.

In some preferred embodiments, the content of sodium alginate in the first mixed solution is 1-5 wt%.

In some preferred embodiments, the content of the polyacrylic acid in the first mixed solution is 1 to 5 wt%.

In some preferred embodiments, the content of the polyvinyl alcohol in the first mixed solution is 0.3 to 1.5 wt%.

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

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

In some preferred embodiments, the lithium-adsorbing material may include, but is not limited to, any one or combination of layered aluminum hydroxide, lithium titanium ion sieve, lithium manganese ion sieve, and the like.

In the embodiment of the invention, the specific lithium adsorption material comprises powders such as a lithium titanium ion sieve, a lithium manganese ion sieve and layered aluminum hydroxide, and the weight ratio of the gel framework material to the adsorbent powder is 1:1-1:18, so that the water content of the gel spheres is not too much, and the gel spheres are 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 more of them.

In some preferred embodiments, the mass ratio of the lithium adsorbing 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 1:1 to 1: 18.

In some preferred embodiments, the preparation method comprises: dissolving 10-15 wt% of anhydrous calcium chloride by using 0.1-0.5mol/L of dilute hydrochloric acid, and after uniformly dissolving, adding 0.5-2 wt% of chitosan and 1-3 wt% of sodium carboxymethylcellulose 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 0.5-1.6 wt% of the weight of the gel ball.

In some preferred embodiments, the crosslinking agent comprises N, N-methylenebisacrylamide, and the crosslinking agent content is 8 to 15 wt% of the gel sphere weight.

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

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

In some more preferable embodiments, the low-temperature freezing temperature is-10 ℃ to-20 ℃ and the time is 12h to 48 h.

In some preferred embodiments, the preparation method comprises:

In some more preferred embodiments, the first ramp rate is 5-10 ℃/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 (i.e., carbonized gel spheres) with lithium adsorbing performance of the present invention comprise:

(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. Dissolving chitosan, sodium carboxymethylcellulose and anhydrous calcium chloride in hydrochloric acid solution to prepare solution B.

(2) Preparing a hollow hard tube with a certain caliber (1-3mm), connecting the hollow tube with a peristaltic pump, vertically placing the hollow tube by using a clamp, slowly dripping the solution A from the hollow tube after being extracted from the peristaltic pump, and placing the solution B below the hollow tube for receiving, thus forming the milky gel ball with the particle size of 1-3 mm.

(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 until the gel balls become light yellow, washing the gel balls with deionized water for several times, and filtering the yellow gel balls for later use.

(4) Before carbonization and temperature rise, pretreatment is carried out: preparing condensate, placing the gel balls in the condensate, and storing for a certain time at low temperature, so as to carry out pretreatment, ensure that the gel balls are not bonded between particles, form ice crystals in the hydrogel after low-temperature freezing, and more easily form pores during carbonization.

(5) And (4) placing the gel balls in the step (4) in a crucible, carrying out inert gas protection in a tubular reaction furnace, quickly heating to the temperature of 100-. The gel ball after carbonization is a gray brown dry porous particle with a reduced particle size, and is washed for multiple times by deionized water to perform an acid resistance detection experiment and an adsorption experiment.

The maintaining time in 100-150 ℃ is 0.5-1h, and the maintaining time in 300-400 ℃ is 3-5h, so that the gel framework is completely digested due to overlong time, and the water is insufficiently removed and the pore passages are not communicated due to overlong time.

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

The adsorption experiment comprises the steps of placing a certain mass of carbonized gel spheres in a self-made lithium-containing solution, oscillating in a water bath for 12-24h, detecting and calculating the equilibrium adsorption capacity of the gel spheres.

According to another aspect of the embodiment of the invention, the carbonized gel material with lithium adsorption performance prepared by the preparation method has porous adsorption sites, abundant through-hole-shaped structures and a specific surface area of 20-50m ² (g) a particle size of 400-。

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

Another aspect of the embodiments of the present invention also provides a lithium adsorbent, including the aforementioned carbonized gel material having lithium adsorption performance.

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

1. according to the invention, the crosslinking initiation of the ternary gel-lithium ion adsorbent composite sphere is a key stage, and the ternary gel is subjected to a certain heating crosslinking reaction, so that the gel framework is more stable, and the adsorbent powder is more uniformly coated.

2. The carbonization pretreatment stage is very important, after the condensate is prepared according to a certain proportion, the gel particles can be independently dispersed in the condensate, after the gel balls are stored for a period of time at low temperature, the gel balls are frozen and firm, a plurality of fine ice crystals are formed inside the gel balls, the gel balls are favorable for being quickly sublimated to form channels during heating treatment, the channels are communicated with each other, and the specific surface area of the gel balls can be greatly improved.

3. The carbonization temperature rise process can ensure that the spheres form a porous structure and are complete in sphere only by controlling a certain temperature range and temperature rise speed, the best effect is achieved when the carbonization temperature is 300-400 ℃, the gel framework is partially digested, the ice crystals are removed, and the through pore channels are formed in the gel spheres.

The gel ball after carbonization is a gray brown dry porous particle with a reduced particle size, and is washed for multiple times by deionized water to perform an acid resistance detection experiment and an adsorption experiment.

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

The adsorption experiment is that a certain mass of carbonized gel balls are placed in a self-made lithium-containing solution, water bath oscillation is carried out for 12-24h, and the equilibrium adsorption capacity is detected and calculated.

Example 1

(1) Dissolving 1g sodium alginate, 1g polyvinyl alcohol, 0.5g polyacrylic acid powder in 97.5g water, stirring and slowly adding 10g lithium adsorbent H ₂ TiO ₃ Uniformly stirring and dispersing the powder to prepare a first mixed solution, namely a feeding solution; 2g of chitosan, 6g of sodium carboxymethylcellulose and 30g of anhydrous calcium chlorideDissolved in 300g of hydrochloric acid solution with a hydrochloric acid concentration of 0.5mol/L to prepare a second mixed solution, namely a receiving solution.

(2) Preparing a hollow pipe, connecting the hollow pipe with the aperture of 1.5mm with a peristaltic pump, vertically placing the hollow pipe, pumping feed liquid from the peristaltic pump, slowly dripping from the hollow pipe, placing receiving liquid below for receiving, and thus forming milky white gel balls with the particle size of 1.3-1.5 mm, as shown in 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 in water bath to 60 ℃, adding the milky gel balls prepared in the step (2), continuously stirring, reacting for 12 hours, and filtering the yellow gel balls for later use.

(4) Mixing 180g of ethanol, 30g of ethylene glycol and 90g of glycerol to obtain condensate, placing the yellow gel balls obtained in the step (3) in the condensate, placing the condensate at the temperature of minus 20 ℃ for 24 hours, taking out the condensate, and filtering the condensate to obtain the frozen gel balls.

(5) And (3) putting the gel balls filtered in the step (4) into a tubular reaction furnace through a crucible for nitrogen protection, firstly heating the temperature in the reaction furnace from room temperature to 150 ℃ at the speed of 10 ℃/min, then preserving heat for 1h, then heating the temperature in the reaction furnace from 150 ℃ to 350 ℃ at the speed of 5 ℃/min, preserving heat for 4h at 350 ℃, and then cooling. Taking out the gel balls carbonized at high temperature, washing and filtering the gel balls by deionized water for three times, storing the gel balls for later use, and finally preparing the gel balls named as TH350-1, wherein the particle size after carbonization is 600-800 μm, the gel balls have a porous structure which is rich and through, and are shown in attached figures 2 and 3 in detail, and the loading capacity of the adsorbent powder before and after carbonization is shown in Table 1.

Example 2

The present example differs from example 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 The powder is stirred and dispersed evenly to prepare a first mixed solution. The hydrogel spheres with the adsorbent powder accounting for 20 wt% are prepared. The carbonized gel ball is named as TH 350-2. The adsorbent powder loading before and after carbonization is shown in table 1.

Example 3

This example differs from example 1 in that: step (1) dissolving 1g of sodium alginate, 5g of polyvinyl alcohol and 1.5g of polyacrylic acid powder in 92.5g of water, stirring and slowly adding 43g of lithium adsorbent H ₂ TiO ₃ The powder was uniformly stirred and dispersed to prepare a first mixed solution, and the rest of the procedure was the same as in example 1. Hydrogel spheres having a sorbent powder content of up to 30 wt.% were prepared. The carbonized gel ball is named as TH 350-3. The adsorbent powder loading before and after carbonization is shown in table 1.

Example 4

This example differs from example 1 in that: step (1) dissolving 1.5g of sodium alginate, 1g of polyvinyl alcohol and 0.5g of polyacrylic acid powder in 97g of water, stirring and slowly adding 43g of lithium adsorbent H ₂ TiO ₃ The powder was uniformly stirred and dispersed to prepare a first mixed solution, and the rest of the procedure was the same as in example 1. Hydrogel spheres with adsorbent powder content of up to 30 wt% were thus prepared. The carbonized gel ball is named as TH 350-4. The adsorbent powder loading before and after carbonization is shown in table 1.

Example 5

The rest steps are the same as example 1, but the temperature rise process in the step (5) is from room temperature to 150 ℃, then the temperature is kept for 1h, the temperature in the furnace is increased from 150 ℃ to 400 ℃ at the speed of 5 ℃/min, the temperature is kept for 2h at 400 ℃, the prepared gel ball is TH400-1, the particle size after carbonization is 600-700 μm, and the loading capacity of the adsorbent powder before and after carbonization is shown in Table 1.

Example 6

The rest steps are the same as example 1, but the temperature rise process in the step (5) is from room temperature to 150 ℃, then the temperature is kept for 1h, the temperature in the furnace is raised from 150 ℃ to 300 ℃ at the speed of 5 ℃/min, the temperature is kept for 5h at 300 ℃, the prepared gel spheres are TH300-1, the particle size after carbonization is 600-700 μm, and the loading capacity 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	Amount of carbonization and dehydration	Adsorbent powder loading capacity before carbonization	Capacity 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％

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

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

Example 7

The present example differs from example 1 in that: the diameter of the hollow tube in the step (2) is 1mm, the particle diameter of the gel ball obtained by dropping is 1.0mm-1.2mm, the rest steps are the same as the example 1, and the particle size after carbonization is 400 μm-500 μm.

Example 8

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

Example 9

The present example differs from example 1 in that: the diameter of the hollow tube in the step (2) is 2.5mm, the particle diameter of the gel ball obtained by dropping is 2.4-2.6mm, the rest steps are the same as the example 1, and the particle size after carbonization is 600-750 μm.

Example 10

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

Example 11

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

Example 12

This example differs from example 1 in that: in step (3), 1.76g of potassium persulfate and 16.5g of N, N-methylenebisacrylamide, which is a crosslinking agent, were added to 300g of isopropyl alcohol, and the procedure was the same as in example 1. The obtained gel spheres have high crosslinking degree and stable carbonized structure, but the pore structure is less in particle distribution and lower in specific surface area which is only 20m compared with the particles in example 1 ² /g。

Example 13

This example differs from example 1 in that: and (4) the condensate in the step (4) consists of 240g of ethanol, 15g of glycol and 45g of glycerol, and the yellow gel balls are stored in the condensate under the temperature condition of-20 ℃ for 12 hours. The rest of the procedure was the same as in example 1. Although the freezing time is short, the carbonization and dehydration effects are not influenced.

Example 14

This example differs from example 1 in that: and (4) the condensate in the step (4) consists of 210g of ethanol, 30g of glycol and 60g of glycerol, and the yellow gel balls are stored in the condensate under the temperature condition of-10 ℃ for 48 hours. The rest of the procedure was the same as in example 1. Although the freezing temperature is higher, the formation of ice crystals and the carbonization and pore-forming effects are not influenced due to longer time.

Example 15

2g of three carbonized gel spheres TH300-1, TH350-1 and TH400-1 are respectively taken and put into 1mol/L hydrochloric acid solution 300g, and after the gel spheres are stored for 7d, 15d, 30d and 60d, the gel sphere dissolution loss is compared, and as a result, the weight loss is less than 0.2 percent, as shown in figure 4, the gel spheres after carbonization can stably exist in the acid solution, and the adsorbent is suitable for acid washing and recycling.

Example 16

In the example 4, the addition amount of the lithium adsorbent powder in the step (1) is 16g, the rest steps are the same as those in the example 4, the finally prepared gel ball is TH400-2, when the addition amount of the lithium adsorbent powder in the step (1) is 22.5g, the rest steps are the same as those in the example 4, the finally prepared gel ball is TH400-3, the lithium ion adsorbent powder used by the TH400-1, the TH400-2, the TH400-3 and the gel ball is used as an adsorbent, after all the adsorbents are subjected to acid pickling and desorption treatment, the elution amount of lithium ions is tested, and then an adsorption experiment is performed, wherein the adsorption experiment is to prepare a solution with the lithium ion concentration of 1.0g/L by using lithium chloride, then 2g of the adsorbent is added into a conical flask, 100g of the lithium chloride solution is added, the lithium ion concentration in the solution is detected after water bath oscillation for 12 hours, and the equilibrium adsorption amount is calculated. As a result, it was found that the adsorption capacity of TH400-3 of the adsorbent particles with a high loading can reach 15mg/g, while the powder material H used ₂ Ti0 ₃ The adsorption capacity is 13mg/g, and the results of kinetic experiments prove that TH400-1, TH400-2 and TH400-3 require 3-4H to reach the adsorption equilibrium, while H requires 3-4H to reach the adsorption equilibrium as shown in figure 5 ₂ Ti0 ₃ It takes 7-8h to reach the adsorption equilibrium.

In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.

While the invention has been described with reference to illustrative embodiments, 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 invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention 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. A preparation method of a carbonized gel material with lithium adsorption performance is characterized by comprising the following steps:

performing crosslinking treatment on the gel spheres;

freezing the gel balls subjected to crosslinking treatment at low temperature;

2. The method of claim 1, wherein: the content of the sodium alginate in the first mixed solution is 1-5 wt%; and/or the content of the polyacrylic acid in the hydrogel system is 1-5 wt%; and/or, the content of the polyvinyl alcohol in the hydrogel system is 0.3-1.5 wt%;

and/or the mass ratio of the first mixed solution to the second mixed solution is 1:1-1: 5;

and/or the particle size of the gel ball is 1-3 mm.

3. The production method according to claim 1, characterized in that: the lithium adsorbing material comprises any one or combination of more of layered aluminum hydroxide, lithium titanium ion sieve and 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 more of; and/or the mass ratio of the lithium adsorbing material to the first mixed solution is 10-30: 100.

4. The production method according to claim 1, characterized in that: the mass ratio of the gel framework material to the lithium adsorbing material is 1:1-1: 18.

5. The method of claim 1, comprising: dissolving 10-15 wt% of anhydrous calcium chloride by using 0.1-0.5mol/L of dilute hydrochloric acid, and after uniformly dissolving, adding 0.5-2 wt% of chitosan and 1-3 wt% of sodium carboxymethylcellulose to obtain the second mixed solution.

6. The method of claim 1, comprising:

preferably, the initiator comprises potassium persulfate and/or ammonium persulfate, and the content of the initiator is 0.5-1.6 wt% of the weight of the gel spheres; and/or the cross-linking agent comprises N, N-methylene-bis-acrylamide, and the content of the cross-linking agent is 8-15 wt% of the weight of the gel spheres; and/or the alcohol solvent comprises isopropanol, and the mass ratio of the alcohol solvent to the gel spheres is 2-5: 1.

7. The method of claim 1, comprising: placing the gel balls subjected to crosslinking treatment in a condensate for low-temperature freezing;

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

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

8. The method of claim 1, comprising:

placing the gel balls frozen at low temperature into a reaction chamber, in a protective atmosphere, firstly heating the temperature in the reaction chamber to 150 ℃ at a first heating rate, maintaining the temperature for 0.5-1h, then continuously heating to 400 ℃ at a second heating rate, maintaining the temperature for 3-5h, and carrying out the carbonization treatment; wherein the first temperature rise rate is greater than the second temperature rise rate;

preferably, the first heating rate is 5-10 ℃/min;

preferably, the second heating rate is 2-5 ℃/min.

9. A carbonized gel material having lithium adsorbing properties prepared by the preparation method of any one of claims 1 to 8, characterized in that: the carbonized gel material with lithium adsorption performance has porous adsorption sites, abundant and through porous structures and a specific surface area of 20-50m ² (g) a particle size of 400-；

And/or the load capacity of the carbonized gel material with the lithium adsorption performance on the specific lithium adsorption material is 80-90 wt%.

10. A lithium adsorbent comprising the carbonized gel material having lithium adsorbing property as claimed in claim 9.