Ion-sieve adsorbent membrane, method for preparing the same, and use thereof

Abstract

The application provides an ion sieve adsorbent membrane and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing a titanium source, a solvent, a weak acid and a lithium source, and then adding the mixture into a polyimide fiber membrane to obtain a polyimide fiber membrane with titanium-based ion sieve precursors deposited on the surface through a hydrothermal reaction; (2) performing calcination treatment on the polyimide fiber membrane with titanium-based ion sieve precursors deposited on the surface to obtain a titanium-based ion sieve composite polyimide fiber membrane; (3) mixing a block copolymer, a second titanium source and an acidic solution, and then spraying the mixture on the surface of the titanium-based ion sieve composite polyimide fiber membrane, and then performing heating and ultraviolet irradiation treatment to obtain the ion sieve adsorbent membrane. The application in-situ grows ion sieves by means of a polyimide fiber membrane as a matrix through a hydrothermal crystallization method, and then sprays a layer of porous titanium dioxide on the ion sieves, so that the lithium ion sieve adsorption capacity is improved, and the problem that the adsorption sites are covered is avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium extraction from salt lakes, and relates to an ion sieve adsorbent film and a preparation method and application thereof. BACKGROUND

[0002] With the increasing consumption of lithium resources year by year, the traditional ore lithium extraction technology cannot meet people's needs, and it is very important to develop a method for quickly and low-cost extracting lithium from brine or seawater rich in lithium resources. At present, there are various ways to extract lithium from liquid resources, the most common of which is the adsorbent method, which uses inorganic or organic adsorbents to repeatedly extract lithium by adsorbing and desorbing lithium. The adsorbent not only has specific selective "Li" performance, but also has excellent cycle performance.

[0003] At present, the biggest problem of inorganic adsorbents is difficult to utilize and recycle. The prepared adsorbents are mostly powders, which are not easy to disperse in lithium-containing resource solutions and are difficult to recycle. Therefore, researchers often combine ion sieves and molding technologies to manufacture macroscopic ion sieves, such as granulation, membrane casting and foaming, etc. However, this molding method directly mixes ion sieves and organic polymers, and a considerable amount of ion sieves are covered by the polymer, resulting in a decrease in adsorption capacity.

[0004] CN117658216A discloses a preparation method of a porous cubic manganese-based lithium ion sieve adsorbent, which comprises the following steps: S10, mixing a lithium source and cubic manganese carbonate according to a molar ratio of Li to Mn of 0.1-1.6, and then grinding to obtain a mixed powder; S20, calcining the mixed powder to obtain a porous cubic manganese-based lithium ion sieve adsorbent.

[0005] CN115069208A discloses a porous fiber bundle-shaped titanium-based lithium adsorbent and a preparation method thereof. The titanium-based lithium adsorbent has a fiber bundle morphology; the diameter of the fiber is 1-1000 microns, and the length is 100-10000 microns; and the titanium-based lithium adsorbent has a porous morphology.

[0006] The above scheme uses pore-forming methods to improve the contact area, but still cannot solve the problem of covering of lithium ion sieve adsorption sites. SUMMARY

[0007] The purpose of the present application is to provide an ion sieve adsorbent film and a preparation method and application thereof. The present application uses polyimide fiber membrane as the substrate to grow ion sieves in situ by hydrothermal crystallization method, and then sprays a layer of porous titanium dioxide thereon, which improves the adsorption capacity of the lithium ion sieve adsorption film and avoids the problem of covering of the adsorption sites.

[0008] To achieve the purpose of the present application, the following technical solutions are adopted:

[0009] In a first aspect, the present application provides a method for preparing an ion sieve adsorbent membrane, the method comprising the following steps:

[0010] (1) mixing a first titanium source, a solvent, a weak acid and a lithium source to obtain a mixed solution, mixing the mixed solution with a polyimide fiber membrane, and subjecting to a hydrothermal reaction to obtain a polyimide fiber membrane with titanium-based ion sieve precursors deposited on the surface thereof;

[0011] (2) subjecting the polyimide fiber membrane with titanium-based ion sieve precursors deposited on the surface thereof to a calcination treatment to obtain a titanium-based ion sieve composite polyimide fiber membrane;

[0012] (3) mixing a block copolymer, a second titanium source and an acidic solution to obtain a mixed solution, spraying the mixed solution on the surface of the titanium-based ion sieve composite polyimide fiber membrane, and subjecting to a heating and ultraviolet irradiation treatment to obtain the ion sieve adsorbent membrane.

[0013] In the present application, the polyimide fiber membrane is used as a substrate, and the titanium-based ion sieve is fixed on the surface of the polyimide fiber membrane by in-situ hydrothermal growth method, so as to realize the formation of lithium ions. Due to the limited growth space of the ion sieve caused by the surface curvature of the nanofiber, the ion sieve presents a needle-like morphology on the surface of the fiber, thereby greatly improving the specific surface area of the ion sieve, which is beneficial to fully contact with the lithium-containing solution for lithium extraction. A layer of porous titanium dioxide is deposited on the surface of the polyimide fiber loaded ion sieve membrane by spraying method. The photocatalytic effect of titanium dioxide can make the membrane have self-cleaning effect, and the photocatalytic degradation of the membrane blocked by organic matter pollution in actual application. The hydrophilicity of titanium dioxide is more conducive to the full immersion of the membrane and the lithium-containing solution, and the porosity will not block the contact between the ion sieve and the solution.

[0014] Preferably, the first titanium source in step (1) comprises any one or a combination of at least two of tetrabutyl titanate, isobutyl titanate, isopropyl titanate or titanium acetylacetonate, and typical but non-limiting combinations include a combination of tetrabutyl titanate and isobutyl titanate, a combination of isobutyl titanate and isopropyl titanate, or a combination of tetrabutyl titanate and titanium acetylacetonate, etc.

[0015] Preferably, the solvent in step (1) comprises ethanol and / or ethylene glycol.

[0016] Preferably, the weak acid in step (1) comprises any one or a combination of at least two of acetic acid, acetic acid or glacial acetic acid.

[0017] Preferably, the volume ratio of the solvent and the weak acid in step (1) is 1:(0.1-0.3), for example, 1:0.1, 1:0.15, 1:0.2, 1:0.25 or 1:0.3, etc., and the value range is not limited to the listed values, and other values not listed in the value range are also applicable.

[0018] Preferably, the lithium source in step (1) comprises a lithium source solution.

[0019] Preferably, the lithium-containing compound in the lithium source solution in step (1) comprises lithium hydroxide, lithium acetate, lithium chloride or lithium nitrate, or a combination of any one or at least two thereof, and typical but non-limiting combinations include a combination of lithium hydroxide and lithium nitrate, a combination of lithium acetate and lithium nitrate, or a combination of lithium chloride and lithium nitrate, etc.

[0020] Preferably, the solvent of the lithium source solution in step (1) comprises ethanol.

[0021] Preferably, the molar ratio of lithium in the lithium source to titanium in the first titanium source in step (1) is 1:(0.5-1.5), such as 1:0.5, 1:0.8, 1:1, 1:1.2 or 1:1.5, etc., and the range is not limited to the listed values, and other values not listed within the range are also applicable.

[0022] Preferably, the mass concentration of the first titanium source in the mixed solution in step (1) is 10%-15%, such as 10%, 11%, 12%, 14% or 15%, etc., and the range is not limited to the listed values, and other values not listed within the range are also applicable.

[0023] Preferably, the polyimide fiber membrane in step (1) is prepared by the following method:

[0024] 4,4-diamino diphenyl ether (ODA), 3,5-diamino benzoic acid (DABA), and pyromellitic dianhydride (PMDA) are mixed and stirred, and then left to stand to remove bubbles to obtain a spinning solution, and the spinning solution is subjected to electrospinning treatment to obtain polyimide nanofibers, and the polyimide nanofibers are dried and then subjected to heating treatment to obtain the polyimide fiber membrane.

[0025] The polyimide has excellent thermal stability and can satisfy high-temperature calcination of titanium-based ion sieves without changing its own properties, the polyimide prepared by the method has carboxyl side groups, and can be crosslinked by thermal decarboxylation at high temperatures, thereby causing the fibers to bond and shrink between them, thereby improving the compressive strength and hydrolysis resistance of the fibers.

[0026] Preferably, the molar ratio of 4,4-diamino diphenyl ether, 3,5-diamino benzoic acid and pyromellitic dianhydride is 1:(0.8-1.2):(1.8-2.5), such as 1:0.8:1.8, 1:1:1.8, 1:1:2, 1:1.2:2.3 or 1:1.1:2.5, etc., and the range is not limited to the listed values, and other values not listed within the range are also applicable.

[0027] Preferably, the total mass concentration of the 4,4-diaminodiphenyl ether, 3,5-diaminobenzoic acid and pyromellitic dianhydride in the spinning solution is 15% to 20%, such as 15%, 16%, 18%, 19% or 20%, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0028] Preferably, the mixing and stirring time is 10 to 24 hours, such as 10 hours, 12 hours, 15 hours, 20 hours or 24 hours, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0029] Preferably, the standing and defoaming time is 12 to 16 hours, such as 12 hours, 13 hours, 14 hours, 15 hours or 16 hours, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0030] Preferably, the humidity of the electrospinning treatment is 40% to 70%, such as 40%, 45%, 50%, 60% or 70%, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0031] Preferably, the voltage of the electrospinning treatment is 14 to 20 kV, such as 14 kV, 15 kV, 16 kV, 18 kV or 20 kV, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0032] Preferably, the needle-to-receiver distance of the electrospinning treatment is 15 to 25 cm, such as 15 cm, 18 cm, 20 cm, 22 cm or 25 cm, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0033] Preferably, the rotation speed of the electrospinning treatment is 150 to 400 rpm, such as 150 rpm, 180 rpm, 200 rpm, 300 rpm or 400 rpm, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0034] Preferably, the heating treatment includes one-step heating treatment and two-step heating treatment.

[0035] Preferably, the temperature of the one-step heating treatment is 100 to 300°C, such as 100°C, 150°C, 200°C, 250°C or 300°C, and the like, not only limited to the listed values, other values not listed in the range of values are also applicable.

[0036] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0037] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0038] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0039] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0040] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0041] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0042] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0043] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0044] Preferably, the one-step heating treatment is performed at a temperature of 350-420℃, for example, 350℃, 360℃, 380℃, 400℃ or 420℃, etc., not limited to the listed values, other values not listed within the range of values are also applicable.

[0045] Preferably, the block copolymer of step (3) comprises any one or a combination of at least two of P123, F127 or F108, and typical but non-limiting combinations include a combination of P123 and F127, a combination of P123 and F108, or a combination of F127 and F108, etc.

[0046] Preferably, the second titanium source of step (3) comprises any one or a combination of at least two of tetrabutyl titanate, isobutyl titanate, isopropyl titanate or titanium acetylacetonate, and typical but non-limiting combinations include a combination of tetrabutyl titanate and isobutyl titanate, a combination of isobutyl titanate and isopropyl titanate, or a combination of tetrabutyl titanate and titanium acetylacetonate, etc.

[0047] Preferably, the molar ratio of the second titanium source and the block copolymer of step (3) is 1: (0.01-0.1), such as 1:0.01, 1:0.02, 1:0.05, 1:0.08 or 1:0.1, etc., and other values not listed in the range are also applicable.

[0048] Preferably, the acidic solution of step (3) comprises ethanol, hydrochloric acid and deionized water.

[0049] Preferably, the concentration of the hydrochloric acid is 20-40 wt%, such as 20 wt%, 25 wt%, 30 wt%, 35 wt% or 40 wt%, etc.

[0050] Preferably, the volume ratio of the ethanol, hydrochloric acid and deionized water is 1: (0.1-0.2):1, such as 1:0.1:1, 1:0.12:1, 1:0.15:1, 1:0.18:1 or 1:0.2:1, etc., and other values not listed in the range are also applicable.

[0051] Preferably, the mass concentration of the second titanium source in the mixed solution of step (3) is 2%-7%, such as 2%, 3%, 5%, 6% or 7%, etc., and other values not listed in the range are also applicable.

[0052] Preferably, the heating and holding treatment is performed after the mixing of step (3).

[0053] Preferably, the temperature of the heating and holding treatment of step (3) is 30-40℃, such as 30℃, 32℃, 35℃, 38℃ or 40℃, etc., and other values not listed in the range are also applicable.

[0054] Preferably, the heating and holding process of step (3) is performed for a time period of 2-4 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, or the like, and other non-enumerated values within this range are also applicable.

[0055] Preferably, the carrier gas for the spraying of step (3) comprises any one or a combination of at least two of nitrogen, argon, or helium, and exemplary but non-limiting combinations include a combination of argon and helium, a combination of nitrogen and helium, or a combination of nitrogen and argon, or the like.

[0056] Preferably, the flow rate for the spraying of step (3) is 2-5 mL / min, such as 2 mL / min, 2.5 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, or the like, and other non-enumerated values within this range are also applicable.

[0057] Preferably, the spraying of step (3) is performed for a time period of 10-60 seconds, such as 10 seconds, 20 seconds, 30 seconds, 50 seconds, 60 seconds, or the like, and other non-enumerated values within this range are also applicable.

[0058] Preferably, the spraying of step (3) is followed by an aging process.

[0059] Preferably, the aging process is performed at a temperature of 20-30 °C, such as 20 °C, 22 °C, 25 °C, 28 °C, 30 °C, or the like, and other non-enumerated values within this range are also applicable.

[0060] Preferably, the aging process is performed at a humidity of 50-80%, such as 50%, 55%, 60%, 70%, 80%, or the like, and other non-enumerated values within this range are also applicable.

[0061] Preferably, the aging process is performed for a time period of 20-40 hours, such as 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, or the like, and other non-enumerated values within this range are also applicable.

[0062] Preferably, the heating and UV irradiation process of step (3) is performed at a temperature of 100-130 °C, such as 100 °C, 105 °C, 110 °C, 120 °C, 130 °C, or the like, and other non-enumerated values within this range are also applicable.

[0063] Preferably, the heating and UV irradiation process of step (3) is performed for a time period of 2-6 hours, such as 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or the like, and other non-enumerated values within this range are also applicable.

[0064] In a second aspect, the present application provides an ion-sieve adsorbent membrane prepared by the method of the first aspect.

[0065] In a third aspect, the present application provides an application of the ion-sieve adsorbent membrane of the second aspect to the extraction of lithium from salt lakes.

[0066] Compared with the prior art, the present application has the following beneficial effects:

[0067] (1) The present application uses a polyimide fiber membrane as a substrate, and deposits a titanium-based lithium ion sieve on the surface of the polyimide fiber membrane and then deposits a layer of porous titanium dioxide, which not only improves the adsorption capacity of the lithium ion sieve, but also avoids the phenomenon of hole blockage caused by the covering of the lithium ion sieve by the polymer, thereby improving the service life of the lithium ion sieve.

[0068] (2) The lithium ion sieve adsorbent membrane of the present application has good lithium extraction and adsorption performance, and the adsorption capacity can reach 28.88 mg / g or more, the adsorption capacity retention rate after 20 cycles can reach 93.51% or more, by adjusting the proportions of the raw materials and the reaction parameters, the adsorption capacity of the ion-sieve adsorbent membrane prepared can reach 29.89 mg / g, the desorption rate can reach 97.12% or more, and the adsorption capacity retention rate after 20 cycles can reach 94.27%. BRIEF DESCRIPTION OF DRAWINGS

[0069] Figure 1 Figure 1 is an SEM image of the ion-sieve adsorbent membrane prepared in Example 1 of the present application.

[0070] Figure 2 Figure 2 is a TEM image of the ion-sieve adsorbent membrane prepared in Example 1 of the present application.

[0071] Figure 3 Figure 3 is an XRD image of the ion-sieve adsorbent membrane prepared in Example 1 of the present application.

[0072] Figure 4 Figure 4 is a reaction schematic diagram of the preparation of the polyimide fiber membrane in Example 1 of the present application. DETAILED DESCRIPTION

[0073] The technical solutions of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0074] Example 1

[0075] This embodiment provides an ion-sieve adsorbent membrane, and the preparation method of the ion-sieve adsorbent membrane is as follows:

[0076] (1) 2.240 g of 4,4-diaminodiphenyl ether, 1.685 g of 3,5-diaminobenzoic acid and 4.883 g of pyromellitic dianhydride (molar ratio of 1:1:2) were weighed and dissolved in N,N-dimethylacetamide to prepare a 15 wt% solution, stirred for 14 h until mixed uniformly, and left to stand for 12 h to degas to obtain a spinning solution. Polyimide acid (PAA) nanofibers were obtained by electrospinning under the condition of room temperature and humidity of 65%, electrospinning voltage of 16 kV, distance between needle tip and receiver of 22 cm, and rotation speed of 200 rpm. The polyimide acid nanofibers were placed in an oven at 85°C overnight for drying, then heated to 280°C in a muffle furnace for 2 h, and then heated to 400°C for 20 min to obtain a heat-crosslinked polyimide fiber membrane (reaction schematic diagram for preparing the polyimide fiber membrane is shown in Figure 4 The tetrabutyl titanate was dissolved in a mixture of anhydrous ethanol and acetic acid in a volume ratio of 1:0.2 to prepare a 12 wt% solution, and lithium hydroxide ethanol solution was added thereto and stirred until mixed uniformly, wherein n(Li):n(Ti) = 1:0.5, and then the polyimide fiber membrane was loaded into an autoclave together with the solution to perform a 160°C hydrothermal reaction for 18 h to obtain a polyimide fiber membrane with titanium-based ion sieve precursor deposited on the surface, wherein the mass ratio of the total mass of lithium hydroxide and tetrabutyl titanate to the mass of the polyimide fiber was 1.3:1;

[0077] (2) After the hydrothermal reaction, the polyimide fiber membrane with titanium-based ion sieve precursor deposited on the surface was placed in a muffle furnace and calcined at 400°C for 2 h to obtain Li2TiO3 fixed on the polyimide fiber. The obtained solid was immersed in a 0.5 mol / L hydrochloric acid solution for 15 h, washed until the washing liquid was neutral, and vacuum dried at 65°C for 12 h to obtain a titanium-based ion sieve composite polyimide fiber membrane:

[0078] (3) Tetrabutyl titanate and P123 in a molar ratio of 1:0.05 were dissolved in a mixture of ethanol, 30 wt% hydrochloric acid and deionized water (volume ratio of ethanol, hydrochloric acid and deionized water 1:0.1:1), the concentration of tetrabutyl titanate was 4 wt%, and after heating at 35°C for 2 h, the mixture was loaded into an airbrush and sprayed on the surface of the polyimide fiber loaded with H2TiO3 membrane at a flow rate of 3 mL / min for 40 s. Then the membrane was placed in an environment with humidity of 70% for aging for 30 h, and then heated at 110°C for 3 h while assisted by ultraviolet irradiation to remove the block copolymer, thereby obtaining the ion sieve adsorbent membrane.

[0079] The SEM image of the ion sieve adsorbent membrane is shown in Figure 1 As can be seen from the SEM image, the ion sieve adsorbent membrane has a long strip fiber structure as a substrate, and a relatively dense needle-like titanium-based ion sieve structure is grown in situ on the substrate. Figure 1

[0080] The TEM image of the ion sieve adsorbent membrane is shown in​Figure 2 As shown in Figure 2 It can be seen that the H2TiO3 is tightly coated with a layer of titanium dioxide outside, with a thickness of about 15-30 nm, and the coating layer has different shades of color, with the lighter part being porous.

[0081] The XRD pattern of the ion sieve adsorbent film is shown in Figure 3 As shown in Figure 3 It can be seen that there are peaks of PI and titanium dioxide, and the main peak of the ion sieve adsorbent film is clear and corresponds to PDF card #33-0831, proving that the titanium ion sieve is synthesized on the polyimide.

[0082] Example 2

[0083] This example provides an ion sieve adsorbent film, and the preparation method thereof is as follows:

[0084] (1) 2.240 g of 4,4-diaminodiphenyl ether, 1.3485 g of 3,5-diaminobenzoic acid, and 4.395 g of pyromellitic dianhydride (molar ratio of 1:0.8:1.8) were weighed and dissolved in N,N-dimethylacetamide to prepare an 18 wt% solution, stirred for 18 h until mixed uniformly, and deaerated for 14 h to obtain a spinning solution. Polyimide acid (PAA) nanofibers were obtained by electrospinning in an environment with a room temperature humidity of 40%, an electrospinning voltage of 14 kV, a needle tip to receiver distance of 15 cm, and a rotation speed of 400 rpm. The polyimide acid nanofibers were placed in an oven at 85°C overnight for drying, then heated to 100°C in a muffle furnace for 2.5 h, and then heated to 350°C for 40 min to obtain a heat-crosslinked polyimide fiber membrane. Isobutyl titanate was dissolved in a mixture of ethylene glycol and acetic acid in a volume ratio of 1:0.1 to prepare a 10 wt% solution, and lithium acetate ethanol solution was added thereto and stirred until mixed uniformly, wherein n(Li):n(Ti)=1:0.8. Then, the polyimide fiber membrane was loaded into an autoclave together with the solution to perform a 100°C hydrothermal reaction for 20 h to obtain a polyimide fiber membrane with titanium ion sieve precursor deposited on the surface, wherein the mass ratio of the total mass of lithium acetate and isobutyl titanate to the mass of the polyimide fiber is 1:1.

[0085] (2) After the hydrothermal reaction, the polyimide fiber membrane with titanium ion sieve precursor deposited on the surface obtained was placed in a muffle furnace and calcined at 450°C for 1 h to obtain Li2TiO3 fixed on the polyimide fiber. The obtained solid was immersed in a 0.5 mol / L hydrochloric acid solution for 15 h, washed until the washing liquid was neutral, and vacuum dried at 65°C for 12 h to obtain a titanium ion sieve composite polyimide fiber membrane:

[0086] (3) Tetra-butyl titanate and F127 with a molar ratio of 1:0.01 were dissolved in a mixture of ethanol, 25wt% hydrochloric acid and deionized water (volume ratio of ethanol, hydrochloric acid and deionized water was 1:0.15:1), and the concentration of tetra-butyl titanate was 2wt%. After heating at 30°C for 4h, the mixture was loaded into a spray gun and sprayed on the surface of the polyimide fiber loaded H2TiO3 film at a flow rate of 2mL / min for 60s. Then the film was placed in an environment with a humidity of 50% for aging for 40h, and then heated at 100°C for 6h while assisted by ultraviolet irradiation to remove the block copolymer, thereby obtaining the ion sieve adsorbent film.

[0087] Example 3

[0088] This example provides an ion sieve adsorbent film, and a preparation method of the ion sieve adsorbent film is as follows:

[0089] (1) 2.240g of 4,4-diamino diphenyl ether, 2.022g of 3,5-diamino benzoic acid and 6.103g of pyromellitic dianhydride (molar ratio of 1:1.2:2.5) were weighed and dissolved in N,N-dimethylacetamide to prepare a 20wt% solution, and stirred for 24h until mixed uniformly, and then left to stand for 16h to remove bubbles to obtain a spinning solution. Polyimide acid (PAA) nanofibers were obtained by electrospinning in an environment with a room temperature and a humidity of 70%, an electrospinning voltage of 20kV, a distance between a needle tip and a receiver of 25cm and a rotation speed of 150rpm. The polyimide acid nanofibers were placed in an oven at 85°C overnight for drying, and then heated to 300°C in a muffle furnace for 1h, and then heated to 420°C for 20min to obtain a heat-crosslinked polyimide fiber film. Isobutyl titanate was dissolved in a mixture of anhydrous ethanol and acetic acid with a volume ratio of 1:0.3 to prepare a 15wt% solution, and lithium acetate ethanol solution was added thereto and stirred until mixed uniformly, wherein n(Li):n(Ti)=1:1.5, and then the polyimide fiber film was loaded into an autoclave together with the solution to perform a 180°C hydrothermal reaction for 4h to obtain a polyimide fiber film with titanium-based ion sieve precursors deposited on the surface, wherein the mass ratio of the total mass of lithium acetate and isobutyl titanate to the mass of the polyimide fiber was 2:1.

[0090] (2) After the hydrothermal reaction, the polyimide fiber film with titanium-based ion sieve precursors deposited on the surface was placed in a muffle furnace and calcined at 300°C for 4h to obtain H4Ti5O 12 The obtained solid was immersed in a 0.5mol / L hydrochloric acid solution for 15h, washed until the pH of the washing liquid was neutral, and vacuum dried at 65°C for 12h to obtain a titanium-based ion sieve composite polyimide fiber film:

[0091] (3) isopropryl titanate and F108 with a molar ratio of 1:0.1 were dissolved in a mixture of ethanol, 20wt% hydrochloric acid and deionized water (volume ratio of ethanol, hydrochloric acid and deionized water 1:0.2:1), the concentration of isopropryl titanate was 7wt%, heated at 40℃ for 2h and then loaded into a spray gun, sprayed on the polyimide fiber loaded H4Ti5O 12 The film was then placed in an environment with humidity of 80% for aging for 20h, and then heated at 130℃ for 2h while assisted by ultraviolet irradiation to remove the block copolymer, to obtain the ion-sieve adsorbent film.

[0092] Example 4

[0093] The difference between this example and Example 1 is only that the mass ratio of the total mass of lithium hydroxide and tetrabutyl titanate to the mass of polyimide fiber is 0.3:1, and other conditions and parameters are exactly the same as those in Example 1.

[0094] Example 5

[0095] The difference between this example and Example 1 is only that the mass ratio of the total mass of lithium hydroxide and tetrabutyl titanate to the mass of polyimide fiber is 2.5:1, and other conditions and parameters are exactly the same as those in Example 1.

[0096] Example 6

[0097] The difference between this example and Example 1 is only that the molar ratio of tetrabutyl titanate and P123 is 1:0.005, and other conditions and parameters are exactly the same as those in Example 1.

[0098] Example 7

[0099] The difference between this example and Example 1 is only that the molar ratio of tetrabutyl titanate and P123 is 1:0.15, and other conditions and parameters are exactly the same as those in Example 1.

[0100] Example 8

[0101] The difference between this example and Example 1 is only that a commercially available polyimide fiber film is used, and other conditions and parameters are exactly the same as those in Example 1.

[0102] Comparative Example 1

[0103] The difference between this comparative example and Example 1 is only that step (3) is not performed, and other conditions and parameters are exactly the same as those in Example 1.

[0104] Comparative Example 2

[0105] The difference between this comparative example and Example 1 is only that no block copolymer is added in step (3), and other conditions and parameters are exactly the same as those in Example 1.

[0106] Performance test:

[0107] 1. Adsorption capacity test: The ion sieve adsorbent film prepared in the above examples and comparative examples was weighed and placed in a solution containing lithium (Li + with a concentration of 100 mg / L and a pH of 10) at a solid-liquid ratio of 1 g: 100 mL, and was placed in a constant temperature oscillator (150 r / min) at 25°C for 8 h of adsorption. The lithium ion content in the solution was measured, and the adsorption capacity was calculated according to the following formula:

[0108]

[0109] where Q e (mg / g) is the equilibrium adsorption capacity, C0and C e are the initial concentration and the equilibrium concentration (mg / L) of Li + , respectively, V (L) is the volume of the mixed solution, and m (g) is the mass of the ion sieve adsorbent

[0110] 2. Desorption rate test: The lithium ion sieve after adsorption was placed in a constant temperature oscillator (150 r / min) at 25°C for 8 h of desorption using 0.5 mol / L HCl. After desorption, the supernatant was collected after filtration with a filter membrane, the lithium ion concentration of the test solution was measured, and the desorption amount was calculated. The desorption amount calculation formula is:

[0111]

[0112] where Q des (%) is the desorption rate; C des (mg / L) is the concentration of lithium in the desorption solution; V' (L) is the volume of the desorption solution; and m' (g) is the mass of the composite adsorbent after adsorption recovery

[0113] 3. Adsorption capacity retention rate test: The above adsorption-acid washing steps were repeated 20 times. The acid washing was performed by placing the lithium ion sieve after adsorption in a constant temperature oscillator (150 r / min) at 25°C for 8 h of desorption using 0.5 mol / L HCl. The adsorption capacity after the 20th cycle was tested, and the percentage of the first adsorption capacity was calculated. The test results are shown in Table 1:

[0114] Table 1

[0115]

[0116] As can be seen from Table 1, according to Examples 1-3, the lithium ion sieve adsorbent film described in the present application has good lithium adsorption performance, the adsorption capacity can reach 28.88 mg / g or more, the desorption rate can reach 97.12% or more, and the adsorption capacity retention rate after 20 cycles can reach 93.51% or more.

[0117] From the comparison of Example 1 and Examples 4-5, it can be seen that in the preparation process of the lithium ion sieve adsorbent film according to the present application, the mass ratio of the total mass of the lithium-containing compound and the first titanium source to the mass of the polyimide fiber membrane will affect the amount of titanium-based ion sieve loaded on the polyimide fiber, and in turn affect the performance of the lithium ion sieve film. Controlling the mass ratio of the total mass of the lithium-containing compound and the first titanium source to the mass of the polyimide fiber membrane to be 00.5-2:1, the amount of titanium-based ion sieve loaded on the polyimide fiber is more appropriate. If the amount of titanium-based ion sieve loaded on the polyimide fiber is too low, most of the polyethylene amine fiber is not shielded and directly contacts the alkaline lithium-containing solution, and the polyethylene amine fiber is severely hydrolyzed. If the amount of titanium-based ion sieve loaded on the polyimide fiber is too high, the adsorption capacity does not increase significantly, and too much titanium-based ion sieve cannot be effectively loaded.

[0118] From the comparison of Example 1 and Examples 6-7, it can be seen that in the preparation process of the lithium ion sieve adsorbent film according to the present application, the ratio of the second titanium source to the block polymer will affect its performance. Controlling the molar ratio of the second titanium source to the block polymer to be 1:0.01-0.1, the performance of the lithium ion sieve film prepared is better. If the amount of block copolymer is too small, it cannot play a sufficient pore-forming role, resulting in that the ion sieve is tightly covered by titanium dioxide, the lithium ion channel is lengthened, and the adsorption capacity and desorption rate are low. If the amount of block copolymer is too large, the pore volume of the titanium dioxide coating layer increases, which is beneficial to the adsorption and deintercalation of lithium ions, but after repeated cycles, the titanium is dissolved and the adsorption capacity retention rate is low.

[0119] From the comparison of Example 1 and Example 8, it can be seen that the polyimide prepared by the method according to the present application contains carboxyl side groups, which can undergo thermal decarboxylation crosslinking at high temperature, thereby causing the fibers to adhere and shrink between them, thereby improving the compressive strength and hydrolysis resistance of the fibers. Compared with commercially available polyimide membranes, the titanium-based ion sieve compounded with the self-made polyimide membrane has better cyclic lithium extraction performance.

[0120] From the comparison of Example 1 and Comparative Example 1, it can be seen that a layer of porous titanium dioxide is deposited on the surface of the polyimide fiber loaded ion sieve film by spraying. The photocatalytic effect of titanium dioxide can make the film have self-cleaning effect. In practical application, the photocatalytic degradation of the film blocked by organic matter pollution can be achieved. The hydrophilicity of titanium dioxide is more conducive to the full wetting of the film with the lithium-containing solution, and the porosity does not block the contact between the ion sieve and the solution.

[0121] From the comparison of Example 1 and Comparative Example 2, it can be seen that no block copolymer is added for pore formation when depositing titanium dioxide. The titanium dioxide deposited on the surface of the polyimide fiber loaded ion sieve film has no porous structure, which is not conducive to the transmission of lithium ions and in turn has low adsorption capacity and desorption rate.

[0122] The applicant states that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A method of making an ion-sieve adsorbent membrane, characterized by, The preparation method comprises the following steps: (1) mixing a first titanium source, a solvent, a weak acid and a lithium source to obtain a mixed solution, mixing the mixed solution with a polyimide fiber membrane, and obtaining a polyimide fiber membrane with a titanium-based ion sieve precursor deposited on the surface through a hydrothermal reaction; (2) performing calcination treatment on the polyimide fiber membrane with the titanium-based ion sieve precursor deposited on the surface to obtain a titanium-based ion sieve composite polyimide fiber membrane; (3) mixing a block copolymer, a second titanium source and an acidic solution to obtain a mixed solution, spraying the mixed solution on the surface of the titanium-based ion sieve composite polyimide fiber membrane, and performing heating and ultraviolet irradiation treatment to obtain the ion sieve adsorbent membrane; In step (1), the first titanium source comprises any one or a combination of at least two of tetrabutyl titanate, isobutyl titanate, isopropyl titanate or titanium acetylacetonate. In step (3), the block copolymer comprises any one or a combination of at least two of P123, F127 or F108. In step (3), the second titanium source comprises any one or a combination of at least two of tetrabutyl titanate, isobutyl titanate, isopropyl titanate or titanium acetylacetonate.

2. The production method according to claim 1, wherein In step (1), the solvent comprises ethanol and / or ethylene glycol.

3. The production method according to claim 1, wherein In step (1), the weak acid comprises any one or a combination of at least two of acetic acid, acetic acid or glacial acetic acid.

4. The production method according to claim 1, wherein In step (1), the volume ratio of the solvent to the weak acid is 1:(0.1-0.3).

5. The production method according to claim 1, wherein In step (1), the lithium source comprises a lithium source solution.

6. The production method according to claim 5, wherein In step (1), the lithium-containing compound in the lithium source solution comprises any one or a combination of at least two of lithium hydroxide, lithium acetate, lithium chloride or lithium nitrate.

7. The production method according to claim 5, wherein In step (1), the solvent of the lithium source solution comprises ethanol.

8. The production method according to claim 1, wherein In step (1), the molar ratio of lithium in the lithium source to titanium in the first titanium source is 1:(0.5-1.5).

9. The production method according to claim 1, wherein In step (1), the mass concentration of the first titanium source in the mixed solution is 10%-15%.

10. The production method according to claim 1, wherein In step (1), the polyimide fiber membrane is prepared by the following method: After mixing, stirring and then standing and degassing 4,4-diamino diphenyl ether, 3,5-diamino benzoic acid and pyromellitic dianhydride with N,N-dimethylacetamide to obtain a spinning solution, performing electrospinning treatment on the spinning solution to obtain polyimide nanofibers, and then drying and heating the polyimide nanofibers to obtain the polyimide fiber membrane.

11. The production method according to claim 10, wherein The molar ratio of 4,4-diamino diphenyl ether, 3,5-diamino benzoic acid and pyromellitic dianhydride in the spinning solution is 1:(0.8-1.2):(1.8-2.5).

12. The production method according to claim 10, wherein The total mass concentration of 4,4-diamino diphenyl ether, 3,5-diamino benzoic acid and pyromellitic dianhydride in the spinning solution is 15%-20%.

13. The production method according to claim 10, wherein The mixing and stirring time is 10-24h.

14. The production method according to claim 10, wherein The standing and degassing time is 12-16h.

15. The production method according to claim 10, wherein The humidity of the electrospinning treatment is 40%-70%.

16. The production method according to claim 10, wherein The voltage of the electrospinning treatment is 14-20kV.

17. The production method according to claim 10, wherein The distance from the needle tip to the receiver of the electrospinning treatment is 15-25cm.

18. The production method according to claim 10, wherein The rotation speed of the electrospinning treatment is 150-400rpm.

19. The production method according to claim 10, wherein The heating treatment comprises one-step heating treatment and two-step heating treatment.

20. The production method according to claim 19, wherein The temperature of the one-step heating treatment is 100-300℃.

21. The production method according to claim 19, wherein The time of the one-step heating treatment is 1-2.5h.

22. The preparation method according to claim 19, characterized in that, The temperature of the two-step heating treatment is 350-420℃.

23. The production method according to claim 19, wherein The time of the two-step heating treatment is 20-40min.

24. The production method according to claim 1, wherein The mass ratio of the total mass of the first titanium source and the lithium-containing compound to the mass of the polyimide fiber membrane in the mixed solution of step (1) is (0.5-2):

1.

25. The production method according to claim 1, wherein The temperature of the hydrothermal reaction in step (1) is 100-180℃.

26. The production method according to claim 1, wherein The time of the hydrothermal reaction in step (1) is 4-20h.

27. The production method according to claim 1, wherein The temperature of the calcination treatment in step (2) is 300-450℃.

28. The production method according to claim 1, wherein The time of the calcination treatment in step (2) is 1-4h.

29. The production method according to claim 1, wherein After the calcination treatment in step (2), acid immersion, washing and drying treatment are performed.

30. The production method according to claim 1, wherein The molar ratio of the second titanium source to the block copolymer in step (3) is 1:(0.01-0.1).

31. The production method according to claim 1, wherein The acidic solution in step (3) comprises ethanol, hydrochloric acid and deionized water.

32. The preparation method according to claim 31, characterized in that, The concentration of the hydrochloric acid is 20-40wt%.

33. The production method according to claim 31, wherein The volume ratio of the ethanol, hydrochloric acid and deionized water is 1:(0.1-0.2):

1.

34. The production method according to claim 1, wherein The mass concentration of the second titanium source in the mixed solution in step (3) is 2%-7%.

35. The preparation method according to claim 1, characterized in that, After the mixing in step (3), heating and holding treatment is performed.

36. The preparation method according to claim 35, characterized in that, The temperature of the heating and holding treatment in step (3) is 30-40℃.

37. The preparation method according to claim 35, characterized in that, The time of the heating and holding treatment in step (3) is 2-4h.

38. The preparation method according to claim 1, characterized in that, The flow rate of the spraying in step (3) is 2-5mL / min.

39. The production method according to claim 1, wherein The time of the spraying in step (3) is 10-60s.

40. The preparation method according to claim 1, characterized in that, After the spraying in step (3), aging is performed.

41. The preparation method according to claim 40, characterized in that, The temperature of the aging is 20-30℃.

42. The preparation method according to claim 40, characterized in that, The humidity of the aging is 50-80%.

43. The preparation method according to claim 40, characterized in that, The time of the aging is 20-40h.

44. The preparation method according to claim 1, characterized in that, The temperature of the heating and ultraviolet irradiation treatment in step (3) is 100-130℃.

45. The preparation method according to claim 1, characterized in that, The time of the heating and ultraviolet irradiation treatment in step (3) is 2-6h.

46. An ion-sieve adsorbent membrane characterized by, The ion-sieve adsorbent membrane is prepared by the method according to any one of claims 1-45.

47. Use of the ion-sieve adsorbent membrane of claim 46, wherein, The ion-sieve adsorbent membrane is used for lithium extraction from salt lakes.

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