Functionalized salicylic acid modified porous resin adsorbent, and preparation method and application thereof

Abstract

This invention discloses a functionalized salicylic acid-modified porous resin adsorbent, its preparation method, and its application, belonging to the field of lithium adsorbent technology. This invention synthesizes a functionalized salicylic acid-modified porous resin adsorbent material. The preparation method is simple, low-cost, and highly efficient, and it can withstand a large number of competing ions such as Na+. + K + Ca 2+ Mg 2+ It can efficiently target and adsorb lithium ions in lithium-containing solutions where coexisting lithium ions, and also has good cycle performance. The maximum adsorption capacity for lithium ions can reach 42.6 mg / g, which effectively solves the technical problems of existing lithium adsorbents such as low adsorption capacity, poor selectivity, high preparation cost, and complex preparation process.

Description

Technical Field

[0001] This invention belongs to the field of lithium adsorbent technology, specifically relating to a functionalized salicylic acid modified porous resin adsorbent, its preparation method, and its application. Background Technology

[0002] Lithium, known as a "green energy metal" and a "strategic resource," is highly valuable in new energy batteries, energy storage technology, industrial manufacturing, and high-tech fields due to its light weight and high energy density. With the advancement of the global energy transition, the demand for lithium resources continues to grow rapidly. However, the development and utilization of lithium resources, whether through lithium extraction from salt lakes or the treatment of spent batteries, generates large amounts of low-concentration lithium-containing wastewater. The lithium in this wastewater is often lost in low-value forms, and the complex water quality conditions further complicate recycling efforts.

[0003] Developing efficient and environmentally friendly technologies for lithium recovery from various low-concentration lithium-containing wastewaters is of great significance. Currently, common recovery methods include solvent extraction, precipitation, electrochemical methods, membrane separation, and adsorption. Among these, adsorption has become the preferred method for targeted lithium-ion adsorption due to its excellent adsorption effect and selectivity. This method has advantages such as simple process, environmental friendliness, low cost, high stability, and high efficiency. Current adsorption materials can be divided into inorganic and organic adsorption materials. Inorganic adsorption materials can broadly include aluminum-based, manganese-based, and titanium-based adsorption materials.

[0004] Compared to inorganic adsorbents, polymeric resins can be designed with specific functional groups (such as crown ethers, phosphate esters, carboxylic acid groups, etc.) to precisely match Li. + The ionic radius and coordination properties of Li enhance the resistance to Li + The selective adsorption capacity of polymeric resins; the porous structure and high specific surface area of ​​polymeric resins provide more active sites, and the adsorption capacity per unit area is generally superior to that of inorganic adsorbents; polymeric resins also have a more open pore structure, Li + With low diffusion resistance and a faster adsorption rate than inorganic adsorbents, it is of great significance to study a polymeric resin adsorbent that is superior in selectivity, stability, adaptability, and processability for the recovery of lithium-containing wastewater with low concentrations and multiple ions. Summary of the Invention

[0005] In view of the content mentioned in the background art, the purpose of this invention is to provide a functionalized salicylic acid modified porous resin adsorbent, its preparation method and application, which effectively solves the technical problems of poor selectivity, low adsorption capacity, high preparation cost and complex process of existing lithium adsorbents.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution: This invention provides a functionalized salicylic acid-modified porous resin adsorbent, the structural formula of which is as follows: .

[0007] In a preferred embodiment, n in the structural formula ranges from 200 to 500.

[0008] The present invention also provides a method for preparing the above-mentioned functionalized salicylic acid modified porous resin adsorbent, comprising the following steps: Step 1: Mix the primary amino resin with the catalyst and solvent, and then slowly add ethyl salicylate solution dropwise under ice bath conditions while stirring the reaction. Step 2: Place the reactants in an oil bath for reflux reaction, and finally wash and dry to obtain the functionalized salicylic acid modified porous resin adsorbent DDC-NH2-SA.

[0009] In a preferred embodiment, the primary amino resin in step 1 is DDC-BiBB-NH2, which is prepared by reacting dodecanol with 2-bromoisobutyryl bromide under catalyst and solvent conditions to obtain DDC-BiBB; then polymerizing it with an amino-containing monomer to obtain the primary amino resin DDC-BiBB-NH2; the catalyst is triethylamine, the solvent is dichloromethane, and the amino-containing monomer is 2-aminoethyl methacrylate.

[0010] In a preferred embodiment, the catalyst in step 1 is sodium hydroxide or potassium hydroxide, and the solvent is N,N-dimethylformamide or dichloromethane.

[0011] In a preferred embodiment, the mass ratio of primary amino resin to ethyl salicylate in step 1 is 1:(1.3-1.5); the ethyl salicylate needs to be prepared as a 0.1-1.0 mol / L solution and added dropwise, and the volume ratio of the ethyl salicylate solution to the solvent used for mixing the primary amino resin is (2-2.5):5.

[0012] In a preferred embodiment, the reflux reaction temperature in the oil bath in step 2 is 110-130℃, and the reaction time is 18-24 h.

[0013] In a preferred embodiment, the solid content of the entire reaction system in steps 1 and 2 is controlled to be 10%-15%.

[0014] The present invention also provides the application of the above-mentioned functionalized salicylic acid modified porous resin adsorbent in lithium extraction.

[0015] As a preferred embodiment, the lithium extraction method is as follows: DDC-NH2-SA is packed into a solid-phase extraction column, and lithium-containing wastewater is flowed through the adsorption column, and the process is repeated multiple times to achieve separation.

[0016] When salicylic acid is grafted onto resin, it exists in an enol form. The oxygen atom in this enol form carries a lone pair of electrons and can act as an electron donor. When it encounters Li+ ions, the enol form loses a proton and forms a chemical bond with the lithium ion as an oxygen anion, further forming a stable ring structure. This ring structure enhances the stability of the resin's binding with the metal ion. In this invention, the enol form in the functionalized salicylic acid-modified porous resin adsorbent is deprotonated to form an electronegative oxygen atom, which becomes the main coordination site for lithium ions. The bidentate coordination forms a stable five- or six-membered chelate ring with the lithium ion, enabling the selective transfer and enrichment of lithium ions from the aqueous phase to the organic phase, thereby achieving efficient lithium extraction.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. The functionalized salicylic acid-modified porous resin adsorbent of the present invention is suitable for the recovery of lithium from complex lithium-containing wastewater and can achieve efficient adsorption of lithium ions in a strongly alkaline solution environment.

[0018] 2. The organic polymer resin adsorbent material prepared by the one-step method of the present invention is in the form of microspheres with a porous structure and high specific surface area, which can provide more active sites. By adjusting the degree of crosslinking and the type of functional groups, it can adapt to a wider pH range and meet the operational requirements of industrial adsorption columns. Attached Figure Description

[0019] Figure 1 This is the Fourier transform infrared spectrum of the functionalized salicylic acid-modified porous resin adsorbent of the present invention.

[0020] Figure 2 The adsorption capacity of the functionalized salicylic acid-modified porous resin adsorbent of this invention varies at different pH values.

[0021] Figure 3 This invention compares the functionalized salicylic acid-modified porous resin adsorbent with the diketone adsorbent, using isothermal adsorption and Langmuir fitting.

[0022] Figure 4 This invention demonstrates the selective adsorption capacity of the functionalized salicylic acid-modified porous resin adsorbent for lithium ions.

[0023] Figure 5 This is the 1H NMR spectrum of the functionalized salicylic acid-modified porous resin adsorbent of the present invention.

[0024] Figure 6 This invention describes the preparation process of the functionalized salicylic acid-modified porous resin adsorbent. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] Example 1 A method for preparing a functionalized salicylic acid-modified porous resin adsorbent, comprising the following steps: 1. Preparation of primary amino resin: Under nitrogen protection, 5 g of dodecanol was weighed and added to a dry two-necked flask, followed by 100 mL of anhydrous dichloromethane and stirring to dissolve. Then, under ice bath conditions, 15 mL of triethylamine was added and stirred for 10 min. Finally, 10 mL of 2-bromoisobutyryl bromide was slowly added dropwise. The ice bath was removed, the temperature was raised to 26 °C, and the mixture was stirred for 12 h under nitrogen protection in the dark to obtain crude DDC-BiBB. The crude product was washed once with saturated sodium bicarbonate and once with saturated brine to obtain pure DDC-BiBB. 5 g of pure DDC-BiBB and 3.0 g of 2-aminoethyl methacrylate were weighed, and 0.5 mL of PMDETA was measured. The mixture was dissolved in 36 mL of anhydrous DMF under nitrogen protection. After vacuuming and nitrogen purging to remove oxygen, 35 mg of purified CuBr catalyst was added, and the mixture was stirred at 40 °C in the dark for 20 h. After purification and drying, the primary amino resin DDC-BiBB-NH2 was obtained.

[0028] The reaction process is as follows:

[0029] 2. Add 2 g of the above primary amino resin DDC-BiBB-NH2, 0.5 g of sodium hydroxide solid, and 100 mL of anhydrous dichloromethane to a dry three-necked flask and stir to mix. Then, slowly add ethyl salicylate solution (prepared by 2.8 g of ethyl salicylate and 45 mL of anhydrous dichloromethane) dropwise under ice bath conditions and stir to react for 2 h. Place the reactants in an oil bath and slowly heat to 120 °C. Reflux the mixture under magnetic stirring for 24 h. Cool, rinse the reactants with pure water by vacuum filtration, then rinse with ethanol solution, and finally dry in a vacuum drying oven at 60 °C for 12 h to obtain the functionalized salicylic acid modified porous resin adsorbent DDC-NH2-SA.

[0030] The functionalized salicylic acid-modified porous resin adsorbent prepared in this embodiment was observed by infrared spectroscopy. Figure 1 Infrared spectrum of functionalized salicylic acid-modified porous resin adsorbent: The image shows that the adsorbent at 3600 cm⁻¹... -1 The characteristic infrared peak of amino groups appeared at 1663 cm⁻¹. -1 The stretching vibration at C=O indicates the formation of a ketone group, proving the successful synthesis of the adsorbent material.

[0031] Example 2 1. Prepare lithium nitrate aqueous solutions with a lithium element concentration of 200 mg / L and pH values ​​of 2, 4, 6, 8, 10, 12, and 14 respectively; take 20 mL of each solution and put it into seven 50 mL Erlenmeyer flasks.

[0032] 2. Weigh out 7 portions of the adsorbent material DDC-NH2-SA (20 mg each) prepared in Example 1, and put the weighed material into conical flasks containing lithium ion aqueous solutions of different concentrations. Place them in a constant temperature shaker with parameters set to 25°C, 180 rpm and 24 h for adsorption experiments.

[0033] 3. Take the ion solutions before and after adsorption in the conical flask, and use an atomic absorption spectrometer (AAS) to determine the lithium ion concentration in the solution.

[0034] Figure 2 The figure shows the adsorption capacity variation at different pH levels. As shown, the material exhibits relatively stable performance at different pH levels, with better adsorption performance in alkaline environments, reaching a maximum adsorption capacity of 46.2 mg / g at pH 12.

[0035] Example 3 The scaled-up DDC-NH2-SA was packed into a solid-phase extraction (SPE) column. A variable-speed peristaltic pump was used to control the flow rate of the sample solution into the adsorption column until all the sample solution had passed through the column. A new adsorption column was then used, and the adsorption process was repeated three times. The final effluent was filtered through a polyethersulfone membrane and diluted before the lithium-ion concentration was determined using atomic absorption spectrometry.

[0036] Figure 3 The isothermal adsorption and fitting curves show that as the lithium concentration in the prepared solution increases, the adsorption performance of the DDC-NH2-SA adsorbent material of this invention gradually increases, eventually reaching an adsorption capacity of approximately 42.6 mg / g. In comparison, the maximum adsorption capacity of commercially available diketone resin adsorbents (structural formula below) is only 5.1 mg / g, indicating that the DDC-NH2-SA of this invention has superior lithium adsorption performance.

[0037]

[0038] Figure 4 The selective adsorption capacity of the functionalized salicylic acid-modified porous resin adsorbent for lithium ions shows that the adsorbent material of the present invention can separate lithium ions from a mixed solution containing lithium ions, sodium ions, potassium ions, calcium ions, and magnesium ions, proving that the adsorbent material of the present invention also has the potential to separate and recover lithium elements in complex lithium-containing wastewater.

[0039] Figure 5 The 1H NMR spectrum of the functionalized salicylic acid-modified porous resin adsorbent; 1 H NMR (400 MHz, DMSO): δ 0.85 (t, 3H), 1.25 (m, 20H), 1.80 (s, 3H), 2.10-2.30 (m, 2H), 2.50(s), 3.30-3.60 (m, 4H), 4.00-4.30 (m, 2H), 6.80-7.50 (m, 4H), 8.00-9.00 (s,1H). Figure 6 This describes the preparation process of functionalized salicylic acid-modified porous resin adsorbents.

[0040] Comparative Example The primary amino resin DDC-BiBB-NH2 prepared in step 1 of Example 1 of this invention was directly used as the adsorbent and packed into a solid-phase extraction column (SPE) using the same testing method as in Example 3. Under the same parameters, the maximum adsorption capacity was measured to be 13.7 mg / g. The comparison shows that the lithium adsorption performance of the functionalized salicylic acid-modified porous resin adsorbent of this invention is significantly improved after graft modification.

[0041] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A functionalized salicylic acid-modified porous resin adsorbent, characterized in that, Its structural formula is as follows: 。 2. The functionalized salicylic acid-modified porous resin adsorbent according to claim 1, characterized in that, In the structural formula, n ranges from 200 to 500.

3. The method for preparing the functionalized salicylic acid-modified porous resin adsorbent according to claim 1 or 2, characterized in that, Includes the following steps: Step 1: Mix the primary amino resin with the catalyst and solvent, and then slowly add ethyl salicylate solution dropwise under ice bath conditions while stirring the reaction. Step 2: Place the reactants in an oil bath for reflux reaction, and finally wash and dry to obtain the functionalized salicylic acid modified porous resin adsorbent DDC-NH2-SA.

4. The preparation method of the functionalized salicylic acid modified porous resin adsorbent according to claim 3, characterized in that, The primary amino resin mentioned in step 1 is DDC-BiBB-NH2, which is prepared by reacting dodecanol with 2-bromoisobutyryl bromide under the conditions of a catalyst and a solvent to obtain DDC-BiBB; then polymerizing it with an amino-containing monomer to obtain the primary amino resin DDC-BiBB-NH2; the catalyst is triethylamine, the solvent is dichloromethane, and the amino-containing monomer is 2-aminoethyl methacrylate.

5. The preparation method of the functionalized salicylic acid modified porous resin adsorbent according to claim 3, characterized in that, The catalyst in step 1 is sodium hydroxide or potassium hydroxide, and the solvent is N,N-dimethylformamide or dichloromethane.

6. The preparation method of the functionalized salicylic acid modified porous resin adsorbent according to claim 3, characterized in that, In step 1, the mass ratio of primary amino resin to ethyl salicylate is 1:(1.3-1.5); the ethyl salicylate needs to be prepared as a 0.1-1.0 mol / L solution and added dropwise, and the volume ratio of the ethyl salicylate solution to the solvent used for mixing primary amino resin is (2-2.5):

5.

7. The method for preparing the functionalized salicylic acid-modified porous resin adsorbent according to claim 3, characterized in that, The reflux reaction temperature in the oil bath described in step 2 is 110-130℃, and the reaction time is 18-24 h.

8. The method for preparing the functionalized salicylic acid-modified porous resin adsorbent according to claim 3, characterized in that, In steps 1 and 2, the solid content of the entire reaction system is controlled at 10%-15%.

9. The application of the functionalized salicylic acid modified porous resin adsorbent according to claim 1 or 2 in lithium extraction.

10. The application according to claim 9, characterized in that, The lithium extraction method is as follows: DDC-NH2-SA is packed into a solid phase extraction column, and lithium-containing wastewater is flowed through the adsorption column. This process is repeated multiple times to achieve separation.

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