A pillar arene supramolecular hydrogel-based dye adsorbent, a preparation method and application thereof

Abstract

The application belongs to the technical field of water treatment, and provides a dye adsorbent based on a pillar arene supramolecular hydrogel and a preparation method and application thereof, wherein the pillar arene supramolecular hydrogel WS is obtained by cross-linking poly(4-styrene sulfonic acid sodium) (PSS) to water-soluble pillar arene WP5 derived from quaternary ammonium salt, and the specific preparation method is as follows: PSS is added to a WP5 aqueous solution, and the WP5 aqueous solution is fully cross-linked under stirring at 40 DEG C, and then the WP5 aqueous solution is cooled to room temperature and left overnight to complete gelation, thereby obtaining the WS. The supramolecular hydrogel has the advantages of low cost, high adsorption efficiency, good adsorption selectivity, easy recycling and the like, and can be easily and industrially produced from cheap and readily available raw materials. The supramolecular hydrogel can efficiently adsorb anionic dyes in water, and has a maximum adsorption capacity of 1309.57 mg / g for chrome black T, and can completely adsorb chrome black T in 5 min, and can effectively separate anionic and cationic dyes, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a dye adsorbent based on columnar aromatic hydrocarbon supramolecular hydrogel, its preparation method and application, specifically its application in removing organic anionic dyes from wastewater. Background Technology

[0002] Organic dyes are widely used in the textile, leather, and cosmetic industries as dyeing and printing agents. However, untreated organic dyes in wastewater cause significant harm to the environment and organisms. Therefore, separating and eliminating organic dyes from wastewater is an urgent priority to protect the environment and organisms. Commonly used methods include photocatalysis, adsorption, flocculation, and ion exchange. Among these methods, adsorption stands out due to its economic feasibility, ease of operation, and high removal efficiency. However, some traditional adsorption materials, such as activated carbon, zeolite, and ion exchange resins, have drawbacks such as poor chemical modifiability, low adsorption selectivity, and non-recyclability.

[0003] Therefore, the preparation of efficient, low-cost, high-adsorption-capacity, highly selective, and regenerable adsorbents is of great significance for treating dyes in wastewater. Supramolecular polymer gels, as adsorbents, have the following advantages: 1. Supramolecular polymer gels are constructed from molecules through various non-covalent interactions, avoiding cumbersome organic synthesis; 2. Supramolecular polymer gels can introduce functional groups through monomers, potentially leading to selective adsorption and other properties; 3. The adsorption performance of supramolecular polymer gels is superior to that of a single monomer, achieving a scale-up effect; 4. Supramolecular polymer gels are degradable under external stimuli, environmentally friendly, and recyclable.

[0004] Columnar [n]aromatics are an important class of supramolecular macrocyclic host molecules, composed of hydroquinone units linked by methylene bridges, possessing a rigid structure and electron-rich cavities. Columnar [n]aromatics are simple to synthesize, require low-cost raw materials, are easily functionalized, and exhibit rich host-guest chemical properties. These advantages make them ideal building blocks for constructing supramolecular polymer gels. The applications of constructing supramolecular polymer gels based on host-guest interactions of columnar [n]aromatics are extensive, including sensing, drug delivery, light harvesting, bioimaging, and adsorption materials. Especially as adsorbents, columnar [n]aromatic-based supramolecular polymer gels possess high adsorption efficiency, are easy to prepare, and are recyclable, providing conditions for preparing supramolecular polymer gels with excellent adsorption properties. Summary of the Invention

[0005] The purpose of this invention is to provide a dye adsorbent based on columnar aromatic supramolecular hydrogel, its preparation method and application, specifically its application in removing organic anionic dyes from wastewater. As an adsorbent, it can efficiently adsorb anionic dyes and selectively separate cationic and anionic dyes.

[0006] This invention is achieved by the following technical solution: a dye adsorbent based on columnar aromatic supramolecular hydrogel, wherein the columnar aromatic supramolecular hydrogel WS is a quaternary ammonium salt-derived water-soluble columnar aromatic hydrocarbon WP5 that crosslinks poly(4-styrene sulfonate), i.e., PSS. The structural formulas of the columnar aromatic hydrocarbon WP5 and poly(4-styrene sulfonate) in the dye adsorbent are shown below: .

[0007] The method for preparing the dye adsorbent based on columnar aromatic supramolecular hydrogel involves adding PSS to an aqueous solution of WP5, controlling the molar ratio of sodium sulfonate groups in WP5 to PSS to be 100:1 to 1:1, stirring at 40°C to allow for full cross-linking, cooling to room temperature, and allowing to stand overnight to complete gelation, thereby obtaining the supramolecular gel WS.

[0008] Furthermore, the molar ratio of the sodium sulfonate groups in WP5 to PSS is 1:1. The PSS has a specification of Mw~70000.

[0009] The present invention also provides the application of the dye adsorbent based on columnar aromatic supramolecular hydrogel in the removal of dyes from aqueous solutions.

[0010] The dye is at least one of Orange Yellow G, Chrome Black T, or sodium acid fuchsin. The specific method is as follows: Prepare 50 mg / L aqueous solutions of Orange Yellow G, Chrome Black T, malachite green chloride, and sodium acid fuchsin for later use; transfer 19 mL of each of the prepared dye aqueous solutions to each location, then add 19 mg of supramolecular hydrogel WS dry powder to each, stir at a uniform speed, and take samples of the solution at regular intervals, taking 1 mL of suspension each time; filter the suspension using a water-based membrane filter; determine the absorbance of each sample at different time intervals using UV-Vis absorption spectroscopy, and calculate the residual dye concentration in each sample using Beer-Lambert law.

[0011] The present invention also provides the application of the dye adsorbent based on columnar aromatic supramolecular hydrogel in the selective adsorption of dyes in wastewater, wherein the concentration of dyes in the wastewater is 50 mg / L.

[0012] The specific method for selective adsorption is as follows: Take 20 mL of the cationic dye / anionic dye binary blend system solution, take out 1 mL of the solution and filter it with a water membrane filter, take the supernatant to detect the absorbance, and record it as the initial absorbance of the mixed dye; add 19 mg of supramolecular hydrogel WS powder to the cationic dye / anionic dye binary blend system solution and mix well, take samples at 5 min and 30 min respectively and monitor the residual concentration of dye.

[0013] Furthermore, the dyes in the cationic / anionic dye binary blend system are Chrome Black T and Malachite Green Chloride, both with a concentration of 50 mg / L.

[0014] After the supramolecular hydrogel WS powder has finished adsorbing, it is regenerated. The specific method is as follows: after adsorption, the supramolecular hydrogel WS powder adsorbent is filtered, added to a saturated ethanol solution of NaOH, stirred for 2 hours to release the adsorbed dye molecules, filtered, washed with deionized water, and vacuum dried overnight at 40°C to complete the regeneration.

[0015] The water-soluble pillar[5]arene WP5 involved in this invention was synthesized according to the published literature: MA Y, JI X, XIANGF, et al. A cationic water-soluble pillar[5]arene: synthesis and host–guest complexation with sodium 1-octanesulfonate [J]. Chemical Communications, 2011, 47(45): 12340-2.

[0016] The poly(4-styrene sulfonate) PSS involved in this invention has a specification of Mw~70000 and was purchased from Adamas.

[0017] The columnar aromatic supramolecular gel dye adsorbent WS described in this invention exhibits selective adsorption of dyes; when cationic and anionic dyes are mixed, only anionic dyes are adsorbed.

[0018] In this invention, the preparation principle of the columnar aromatic supramolecular gel dye adsorbent WS is as follows: there is an electrostatic interaction between the quaternary ammonium salt-derived water-soluble columnar aromatic hydrocarbon WP5 and the negatively charged poly(4-styrene sulfonate) PSS, thereby forming a supramolecular polymer gel.

[0019] Compared with existing technologies, the columnar aromatic hydrocarbon supramolecular gel dye adsorbent WS described in this invention is made from inexpensive and readily available raw materials, is simple and convenient to prepare, consumes little energy, and can efficiently adsorb anionic dyes. The adsorbed dyes can also be recycled and reused, and it can effectively separate anionic and ionic dye ions. It is a green and environmentally friendly dye adsorbent. Attached Figure Description

[0020] Figure 1 The UV absorption spectra of WS for the adsorption of Orange G, Eriochrome Black T, sodium salt of acid fuchsin, and chloride of malachite green are shown in the figure. In the figure: (a) is the adsorption of Orange G by WS, (b) is the adsorption of Eriochrome Black T by WS, (c) is the adsorption of sodium salt of acid fuchsin by WS, and (d) is the adsorption of chloride of malachite green by WS.

[0021] Figure 2 The graph shows the selective adsorption effect of WS on the binary mixed solution of chrome black T-malachite green chloride; in the figure: (a) is the macroscopic change, (b) is the ultraviolet change;

[0022] Figure 3 The graph shows a comparison of the adsorption effects of WS and activated carbon on chrome black T. In the graph: (a) is the UV absorption spectrum of activated carbon (AC) on the adsorption effect of chrome black T over time, and (b) is the adsorption efficiency of both on chrome black T over time.

[0023] Figure 4 The fitting results and parameters of WS for Chrome Black T using the Langmuir model are shown.

[0024] Figure 5 The bar chart shows the adsorption efficiency of WS on Chrome Black T after five consecutive cycles of use. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[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 to which this invention pertains, and all materials publicly cited herein and cited by them are incorporated herein by reference.

[0027] Equivalent technologies of the specific embodiments described herein that are apparent to those skilled in the art through routine experimentation are included in this application.

[0028] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the instruments and equipment used in the following examples are all standard laboratory instruments and equipment; unless otherwise specified, the experimental materials used in the following examples were all purchased from regular biochemical reagent stores.

[0029] Example 1: Preparation of supramolecular hydrogel: 255.38 mg (0.113 mol) of columnar aromatic hydrocarbon WP5 powder and 232.6 mg (0.113 mol) of poly(4-styrene sulfonate) PSS powder were added to 0.5 mL of water. This ratio is the optimal ratio (1:1). The mixture was stirred at 40 °C to allow it to fully crosslink. After cooling to room temperature, it was allowed to stand overnight to complete gelation, which yielded a supramolecular polymer hydrogel, labeled as WS.

[0030] The PSS used in this invention has a specification of Mw~70000. The water-soluble pillar[5]arene used was synthesized according to the published literature: MA Y, JI X, XIANG F, et al. A cationic water-soluble pillar[5]arene: synthesis and host–guest complexation with sodium 1-octanesulfonate[J]. Chemical Communications, 2011, 47(45): 12340-2.

[0031] Example 2: Adsorption of dyes in aqueous solution by supramolecular hydrogel WS: 19 mL each of 50 mg / L aqueous solutions of Orange Yellow G, Chrome Black T, Malachite Green Chloride, and Acid Fuchs Red Sodium Salt dyes were measured and placed in four reagent bottles. Four 19 mg portions of gel powder were weighed and added to the respective reagent bottles. The mixture was stirred at a constant speed, and samples were taken periodically. Subsequently, the samples were filtered using an aqueous membrane filter, and the supernatant was analyzed to calculate the residual dye concentration in each sample. The results are as follows: Figure 1 As shown, WS has almost no adsorption effect on cationic dyes, but has a very good effect on three anionic dyes. The adsorption efficiencies for Orange G, Eriochrome Black T, and Acid Fuchs Sodium Salt are 88.13%, 99.66%, and 97.26%, respectively.

[0032] Example 3: Langmuir isotherm study of supramolecular hydrogel WS on Eriochrome Black T: In the adsorption isotherm study, five 5 mL sample vials were used, and 5 mg of supramolecular hydrogel WS was placed in each vial. Then, 5 mL of Eriochrome Black T solution with a concentration of 200–900 mg / L was added to each vial. The mixture was continuously stirred for 36 h to ensure adsorption equilibrium was reached. Samples were then taken and filtered through an aqueous inorganic membrane filter. Finally, the residual dye concentration was determined using UV-Vis absorption spectroscopy. Figure 4 As shown, the adsorption results of Chrome Black T were fitted using the Langmuir model, and the maximum adsorption capacity of WS for Chrome Black T was calculated to be 1309.57 mg / g. This result is better than the maximum adsorption capacity of all previously reported adsorbents for Chrome Black T.

[0033] Example 4: Selective adsorption effect of supramolecular hydrogel WS on cationic and anionic dyes: 10 mL each of 100 mg / L Chrome Black T and Malachite Green chloride dye solutions were mixed. 1 mL of the mixture was taken and filtered through a water-based membrane filter. The absorbance of the supernatant was measured and recorded as the initial absorbance of the mixed dye. 19 mg of the gel powder was weighed and added to reagent bottles. Samples were taken at 5 min and 30 min to monitor the residual dye concentration. Figure 2 As shown, WS has a very good selective adsorption effect, and can completely adsorb chrome black T in 5 minutes without affecting malachite green chloride.

[0034] Example 5: Performance Comparison Test of Supramolecular Hydrogel WS and Activated Carbon Regarding Chrome Black T: 19 mL of 50 mg / L Chrome Black T dye solution was measured into a reagent bottle. 19 mg of dry gel powder WS and 19 mg of activated carbon (AC) powder were weighed and added to the reagent bottle, stirred uniformly, and samples were taken periodically and filtered through a filter membrane. Finally, the absorbance of each filtrate sample at each time point was measured using UV-Vis absorption spectroscopy. The residual dye concentration in each sample was calculated using Beer-Lambert's law. The results are as follows: Figure 3 As shown, WS exhibits better adsorption rate and efficiency for Chrome Black T than activated carbon.

[0035] Example 6: Recycling Test of Supramolecular Hydrogel WS Adsorbent: The aqueous solution of supramolecular hydrogel WS powder after adsorbing Eriochrome Black T was filtered and dried, then added to a saturated ethanol solution of NaOH. The solution was stirred at room temperature for 2 hours to release the adsorbed Eriochrome Black T. The solution was then filtered and washed, vacuum dried overnight at 40°C, collected, weighed, and used for the next recycling test. Results are as follows: Figure 5 As shown, even after 5 cycles of testing, the adsorption performance of supramolecular hydrogel WS for Chrome Black T remained almost unchanged.

[0036] Example 7: Preparation of supramolecular hydrogel: WP5 powder and PSS powder were mixed at a molar ratio of 100:1, and the remaining methods were the same as those described in Example 1.

[0037] Example 8: WP5 powder and PSS powder were mixed at a molar ratio of 10:1, and the remaining methods were the same as those described in Example 1.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dye adsorbent based on columnar aromatic hydrocarbon supramolecular hydrogel, characterized in that: The water-soluble columnar aromatic hydrocarbon WP5, derived from a quaternary ammonium salt and based on columnar aromatic hydrocarbon supramolecular hydrogel WS, crosslinks with sodium poly(4-styrene sulfonate), i.e., PSS. The structural formulas of the columnar aromatic hydrocarbon WP5 and sodium poly(4-styrene sulfonate) of the dye adsorbent are shown below: .

2. The method for preparing the dye adsorbent based on columnar aromatic hydrocarbon supramolecular hydrogel as described in claim 1, characterized in that: PSS was added to the aqueous solution of WP5, and the molar ratio of sodium sulfonate groups in WP5 to PSS was controlled to be 100:1 to 1:

1. The mixture was stirred at 40°C to allow it to fully crosslink. After cooling to room temperature, it was allowed to stand overnight to complete the gelation, thus obtaining the supramolecular gel WS.

3. The preparation method according to claim 2, characterized in that: The molar ratio of sodium sulfonate groups in WP5 to PSS is 1:

1.

4. The preparation method according to claim 2, characterized in that: The specifications of the PSS are Mw~70000.

5. The application of the dye adsorbent based on columnar aromatic supramolecular hydrogel as described in claim 1 in the removal of dyes from aqueous solutions.

6. The application according to claim 5, characterized in that: The dye is at least one of Orange Yellow G, Chrome Black T, malachite green chloride, or sodium acid fuchsin. The specific method is as follows: Prepare 50 mg / L aqueous solutions of Orange Yellow G, Chrome Black T, malachite green chloride, and sodium acid fuchsin for later use; transfer 19 mL of each of the prepared dye aqueous solutions to each sample, then add 19 mg of supramolecular hydrogel WS dry powder to each sample, stir at a uniform speed, and take samples of the solution at regular intervals, taking 1 mL of suspension each time; filter the suspension using a water-based membrane filter; determine the absorbance of each sample at different time intervals using UV-Vis absorption spectroscopy, and calculate the residual dye concentration in each sample using Beer-Lambert law.

7. The application of the dye adsorbent based on columnar aromatic supramolecular hydrogel as described in claim 1 in the selective adsorption of dyes in wastewater, characterized in that: The concentration of dye in the wastewater is 50 mg / L.

8. The application according to claim 7, characterized in that: The specific method for selective adsorption is as follows: Take 20 mL of the cationic dye / anionic dye binary blend system solution, take out 1 mL of the solution and filter it with an aqueous membrane filter, take the supernatant and measure the absorbance, and record it as the initial absorbance of the mixed dye. 19 mg of supramolecular hydrogel WS powder was added to a binary blend of cationic and anionic dyes and mixed thoroughly. Samples were taken at 5 min and 30 min to monitor the residual concentration of the dyes.

9. The application according to claim 8, characterized in that: The dyes in the binary blend system of cationic / anionic dyes are Chrome Black T and Malachite Green chloride, both with a concentration of 50 mg / L.

10. The application according to claim 8, characterized in that: After the supramolecular hydrogel WS powder has finished adsorbing, it is regenerated. The specific method is as follows: after adsorption, the supramolecular hydrogel WS powder adsorbent is filtered, added to a saturated ethanol solution of NaOH, stirred for 2 hours to release the adsorbed dye molecules, filtered, washed with deionized water, and vacuum dried overnight at 40°C to complete the regeneration.

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