High-selectivity bromine ion selective adsorbent and application thereof in seawater bromine extraction

Abstract

The invention belongs to the field of adsorbents, and particularly relates to a high-selectivity bromine ion selective adsorbent and application thereof in seawater bromine extraction. Sodium lignin sulfonate and glucose are used as precursor solutions to prepare a precursor solution, polyvinylpyrrolidone and melamine react with the precursor solution to prepare a homogeneous-phase composite solution, and the homogeneous-phase composite solution is used for preparing the bromine ion selective adsorbent. The preparation method comprises the following steps: preparing a porous organic precursor through freeze drying, calcining at a low temperature, impregnating with a urea solution, drying, calcining at a high temperature, reacting on the surface of the porous organic precursor through copper nitrate and sodium thiosulfate, and loading a copper-based active component, so as to prepare the high-selectivity bromine ion selective adsorbent which is adsorbed and desorbed in a weak electric field environment. The capacity retention rate is still 90% after 10 times of circulation, so that the high-selectivity bromine ion selective adsorbent still keeps good adsorption and cyclic regeneration capacity in a weak current environment, and is particularly suitable for extracting bromine from seawater.

Description

Technical Field

[0001] This invention relates to the field of adsorbent technology, specifically to a highly selective bromide ion adsorbent and its application in seawater bromine extraction. Background Technology

[0002] In the process of extracting bromine resources from seawater or high-salinity brine, bromide ions are usually present at extremely low concentrations and coexist with a large number of competing anions such as chloride ions, which places high demands on the selectivity and adsorption capacity of the adsorbent.

[0003] However, in certain special scenarios, such as atmospheric / natural electric fields where a weak electric field distribution exists in the air (e.g., an enhanced electric field before a thunderstorm), the charge distribution on the surface of bromide ion adsorbents (especially metal oxides) may undergo slight changes, leading to a slight alteration in the polarization of the adsorption sites.

[0004] Surrounding electromagnetic interference: The weak electromagnetic field near the solar substation may indirectly affect the migration behavior of ions in the water, thereby affecting the ion exchange rate of the adsorbent. In particular, such accidents are prone to occur if there is a slight leakage or grounding wire leakage, which may cause some properties of the adsorbent to fail during bromine extraction from seawater in the nearby area due to the presence of the weak electric field.

[0005] Based on this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a highly selective bromide ion selective adsorbent and its application in seawater bromine extraction, so as to solve the above-mentioned problems.

[0007] The purpose of this invention is to provide a highly selective bromide ion adsorbent and its application in seawater bromine extraction, which can be achieved through the following technical solutions:

[0008] In a first aspect, a highly selective bromide ion selective adsorbent is prepared by using sodium lignosulfonate and glucose as precursor solutions to prepare a precursor solution, reacting polyvinylpyrrolidone and melamine with the precursor solution to prepare a homogeneous composite solution, freeze-drying to obtain a porous organic precursor, first calcining at low temperature and then impregnating with urea solution, drying, and then calcining at high temperature, and loading copper-based active components onto its surface by reacting copper nitrate and sodium thiosulfate, thereby obtaining the highly selective bromide ion selective adsorbent.

[0009] Secondly, a method for manufacturing a highly selective bromide ion adsorbent includes the following steps: S1: Sodium lignosulfonate, glucose and deionized water are heated to react and obtain a precursor solution; S2: Polyvinylpyrrolidone and melamine are added to the precursor solution and heated to react, resulting in a homogeneous composite solution; S3: Freeze-dry the homogeneous composite solution to obtain porous organic precursor powder; S4: The porous organic precursor powder was calcined at 355~360℃ under a nitrogen atmosphere, and after natural cooling, it was dispersed in a urea solution, filtered, and the filter residue was dried to obtain the modified porous organic precursor. S5: The modified porous organic precursor is calcined at 820~830℃ under a nitrogen atmosphere to obtain a porous carbon framework. S6: A porous carbon framework is dispersed in an organic solvent, copper nitrate and sodium thiosulfate are added, and the mixture is heated to react. S7: The product obtained after the S6 reaction is completed is filtered, washed with water, and dried under vacuum to obtain the highly selective bromide ion selective adsorbent.

[0010] Furthermore, in S1, the mass ratio of sodium lignosulfonate to glucose is 1:(5~6).

[0011] Furthermore, in S1, the reaction temperature is 80~85℃.

[0012] Furthermore, in S2, the mass ratio of polyvinylpyrrolidone to melamine is 25:40.

[0013] Furthermore, in S2, the reaction temperature is 80~85℃.

[0014] Furthermore, in S4, the mass fraction of the urea solution is 13%.

[0015] Furthermore, ultrasonic-assisted dispersion is required when impregnating urea solution.

[0016] Furthermore, the organic solvent is one or more of methanol, ethanol, and propanol.

[0017] Thirdly, the application of the highly selective bromide ion selective adsorbent in seawater bromine extraction.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, a cross-linked network rich in phenolic hydroxyl and sulfonic acid groups is constructed through the synergistic polycondensation of sodium lignosulfonate and glucose. Low-temperature pre-carbonization retains some oxygen-containing functional groups. During high-temperature carbonization, ammonia generated from melamine decomposition and pyrrole / pyridine nitrogen formed from PVP pyrolysis are co-doped into the carbon framework. Simultaneously, the sulfur element inherent in sodium lignosulfonate is converted into thioether, thiol, and thiophene structures, forming uniformly distributed nitrogen-sulfur bifunctional sites. Based on this, the process is further optimized by employing a preliminary calcination followed by urea impregnation, and then final calcination, thereby constructing gradient channels with a size sieving effect and a stable five-membered ring Cu–N–S complex structure for densely anchoring active sites. This structure has a specific recognition ability for bromide ions, thus achieving highly selective capture of bromide ions. Furthermore, the special nitrogen-sulfur co-doped framework structure of this invention also remains stable under an electric field.

[0019] Although the adsorption capacity increases slightly under a weak electric field, without optimizing the structure and performance of the adsorbent, the capacity retention rate after 10 cycles will decrease from 78% to 5%, significantly reducing the number of cycles. However, the highly selective bromide ion adsorbent described in this invention maintains a capacity retention rate of 90% after 10 cycles under a weak electric field, demonstrating that it retains excellent adsorption and regeneration capabilities even in weak electric environments, making it particularly suitable for bromine extraction from seawater. Detailed Implementation

[0020] The present invention will be further described in detail below through specific embodiments.

[0021] Example 1 S1: Add 10g sodium lignosulfonate and 50g glucose (mass ratio 1:5) to 800mL deionized water to prepare a mixed solution with a total solid content of 7.5%. Stir the mixture at 80℃ for 4 hours to obtain the precursor solution. S2: Add 24g of polyvinylpyrrolidone (3% of the total mass of the solution) and 40g of melamine (5% of the total mass) to the precursor solution, and continue stirring at 85℃ for 5.5 hours to obtain a homogeneous composite solution; S3: The homogeneous composite solution was placed in a freeze dryer and dried at -40℃ and 20pa for 36 hours to obtain a porous organic precursor powder; S4: Place the porous organic precursor powder into a tube furnace, introduce nitrogen gas, heat to 360℃ and hold for 5 hours. After natural cooling, soak it in a 13% urea solution (material-liquid ratio 1g:8mL) and disperse it with ultrasonic assistance for 2 hours. Filter, dry the filter residue, and obtain the modified porous organic precursor. S5: The modified porous organic precursor is placed in a tube furnace, nitrogen is introduced, the temperature is raised to 820℃ and held for 5 hours, and then naturally cooled to obtain a nitrogen-sulfur co-doped porous carbon framework. S6: Disperse 10g of porous carbon framework in 400mL of ethanol, add 0.6g of copper nitrate (6%) and 0.52g of sodium thiosulfate (1.5 times the molar amount of copper nitrate), and stir the reaction at 52℃ for 7 hours. S7: Filter by suction, wash with deionized water until neutral, and dry under vacuum at 70°C for 18 hours to obtain adsorbent A1.

[0022] Example 2 S1: Add 10g sodium lignosulfonate and 60g glucose (mass ratio 1:6) to 1000mL deionized water to prepare a mixed solution. Stir the mixture at 85℃ for 3 hours to obtain the precursor solution. S2: Add 25g of polyvinylpyrrolidone and 40g of melamine to the precursor solution, and continue stirring at 80℃ for 6 hours to obtain a homogeneous composite solution; S3: The homogeneous composite solution was placed in a freeze dryer and dried for 36 hours to obtain a porous organic precursor powder; S4: Place the porous organic precursor powder into a tube furnace, introduce nitrogen gas, heat to 355℃ and hold for 5.5 hours. After natural cooling, soak it in a 13% urea solution (material-liquid ratio 1g:8mL) and disperse it with ultrasonic assistance for 2 hours. Filter, dry the filter residue, and obtain the modified porous organic precursor. S5: The modified porous organic precursor is placed in a tube furnace, nitrogen is introduced, the temperature is raised to 830℃ and held for 5 hours, and then naturally cooled to obtain a nitrogen-sulfur co-doped porous carbon framework. S6: Disperse 10g of porous carbon framework in 430mL of ethanol, add 0.6g of copper nitrate and 0.52g of sodium thiosulfate, and stir the reaction at 52℃ for 7 hours. S7: Filter by suction, wash with deionized water until neutral, and dry under vacuum to obtain adsorbent A2.

[0023] Comparative Example 1 S1: Add 10g sodium lignosulfonate and 50g glucose (mass ratio 1:5) to 800mL deionized water to prepare a mixed solution with a total solid content of 7.5%. Stir the mixture at 80℃ for 4 hours to obtain the precursor solution. S2: Add 24g of polyvinylpyrrolidone (3% of the total mass of the solution) and 40g of melamine (5% of the total mass) to the precursor solution, and continue stirring at 80℃ for 6 hours to obtain a homogeneous composite solution; S3: The homogeneous composite solution was placed in a freeze dryer and dried at -40℃ and 20pa for 36 hours to obtain a porous organic precursor powder; S4: Place the porous organic precursor powder into a tube furnace, introduce nitrogen gas, heat to 360℃ and hold for 2 hours, then heat to 820℃ and hold for 5 hours, and cool naturally to obtain a nitrogen-sulfur co-doped porous carbon framework. S5: Disperse 10g of porous carbon framework in 400mL of ethanol, add 0.6g of copper nitrate (6%) and 0.52g of sodium thiosulfate (1.5 times the molar amount of copper nitrate), and stir the reaction at 52℃ for 7 hours. S6: Filter by suction, wash with deionized water until neutral, and dry under vacuum at 70°C for 18 hours to obtain the adsorbent.

[0024] Comparative Example 2 The difference between this example and Example 1 is that the 13% urea solution is replaced with an ammonium nitrate solution with the same nitrogen content and a 17.3% urea solution. All other aspects are the same.

[0025] Comparative Example 3 The difference between this example and Example 1 is that the 13% urea solution is replaced with a 50% ethanol aqueous solution, while the rest are the same.

[0026] Comparative Example 4 The difference between this example and Example 1 is that only S4 is different; in this example, S4 is: the porous organic precursor powder is soaked in a 13% urea solution (material-liquid ratio 1g:8mL) and ultrasonically dispersed for 2 hours, filtered, and the filter residue is dried to obtain the modified porous organic precursor; the remaining steps are the same.

[0027] The above adsorbent was used to adsorb bromide ions in simulated seawater (bromine ion 68 mg / L, chloride ion 19000 mg / L) under the following conditions: pH=6.0, adsorbent-to-liquid ratio 1.0 g / L, 30℃, 2 hours. Desorption was performed using 0.3 mol / L ammonium thiocyanate solution at a liquid-to-liquid ratio of 15 mL / g for 60 minutes. The adsorption capacity was measured after 10 cycles. The "no electric field environment" refers to the current conventional experimental environment; while the 3.6V weak current environment refers to the application of a 3.6V DC power supply to the brine and during desorption. The results are shown in Table 1.

[0028] Table 1

[0029] The capacity retention rate after 10 cycles at 3.6V in Table 1 is indicated by " / ", meaning it cannot be measured.

[0030] As shown in Table 1, the process of first calcining, then impregnating urea, and finally calcining again is beneficial for forming a more stable nitrogen-sulfur co-doped porous carbon framework under an electric field environment.

[0031] Comparative Example 5 In Example 1, the capacity retention rate after 10 cycles at a voltage of 3.6V is shown in Table 2 when the mass fraction of the urea solution changes: Table 2

[0032] As shown in Table 2, the capacity retention rate increases with the increase of the urea solution mass fraction, but remains relatively stable within the 13%~20% range; however, it decreases significantly after exceeding 20%. Considering cost, a urea solution mass fraction of 13% is preferred.

[0033] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0034] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A highly selective bromide ion adsorbent, characterized in that: A precursor solution was prepared using sodium lignosulfonate and glucose as precursor solutions. A homogeneous composite solution was prepared by reacting polyvinylpyrrolidone and melamine with the precursor solution. A porous organic precursor was prepared by freeze drying. The precursor was first calcined at low temperature and then impregnated with urea solution. After drying, it was calcined at high temperature. Copper-based active components were loaded onto its surface by reacting copper nitrate and sodium thiosulfate, thereby obtaining the highly selective bromide ion selective adsorbent.

2. The method for manufacturing a highly selective bromide ion adsorbent according to claim 1, characterized in that, Includes the following steps: S1: Sodium lignosulfonate, glucose and deionized water are heated to react and obtain a precursor solution; S2: Polyvinylpyrrolidone and melamine are added to the precursor solution and heated to react, resulting in a homogeneous composite solution; S3: Freeze-dry the homogeneous composite solution to obtain porous organic precursor powder; S4: The porous organic precursor powder was calcined at 355~360℃ under a nitrogen atmosphere, and after natural cooling, it was dispersed in a urea solution, filtered, and the filter residue was dried to obtain the modified porous organic precursor. S5: The modified porous organic precursor is calcined at 820~830℃ under a nitrogen atmosphere to obtain a porous carbon framework. S6: A porous carbon framework is dispersed in an organic solvent, copper nitrate and sodium thiosulfate are added, and the mixture is heated to react. S7: The product obtained after the S6 reaction is completed is filtered, washed with water, and dried under vacuum to obtain the highly selective bromide ion selective adsorbent.

3. The manufacturing method according to claim 2, characterized in that: In S1, the mass ratio of sodium lignosulfonate to glucose is 1:(5~6).

4. The manufacturing method according to claim 2, characterized in that: In S1, the reaction temperature is 80~85℃.

5. The manufacturing method according to claim 2, characterized in that: In S2, the mass ratio of polyvinylpyrrolidone to melamine is 25:

40.

6. The manufacturing method according to claim 2, characterized in that: In S2, the reaction temperature is 80~85℃.

7. The manufacturing method according to claim 2, characterized in that: In S4, the mass fraction of the urea solution is 13%.

8. The manufacturing method according to claim 7, characterized in that: Ultrasonic dispersion is required when impregnating urea solution.

9. The manufacturing method according to claim 2, characterized in that: The organic solvent is one or more of methanol, ethanol, and propanol.

10. The application of the highly selective bromide ion selective adsorbent as described in claim 1 in bromine extraction from seawater.

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