A broad-spectrum anionic dye adsorbent and its preparation method and application

Abstract

The present application relates to the technical field of dye adsorbent chemistry, and particularly relates to a broad-spectrum anionic dye adsorbent as well as a preparation method and application thereof, the adsorbent is a novel high-performance PEI / SA adsorbent, can efficiently adsorb various anionic dyes, has a large adsorption capacity, a high adsorption rate, is biodegradable, and can be recycled. The adsorbent provided by the present application has a simple preparation process, does not need heating, is completed in one step, and has no pollutant emission in the preparation process; does not need further cleaning, purification, and can be directly used after product drying; and product preparation does not need special equipment. The present application solves the problem of a complex and lengthy preparation process of traditional adsorbents. The present application has low investment cost, strong practicability, and is easy to realize industrialization and popularization. The adsorbent provided by the present application can be used for adsorbing Congo red, amino black 10B, acid blue 25, acid magenta, methyl orange, acid green 25, sunset yellow, indigo carmine, alizarin red S, direct red 7, titan yellow, and methyl blue.

Description

Technical Field

[0001] The present invention relates to the technical field of dye adsorbent chemistry, and in particular to a polyethyleneimine / sodium alginate adsorbent, its preparation and its application in adsorbing anionic dyes. Background Art

[0002] Organic dyes in dyeing and printing wastewater, especially those that are difficult to degrade, easily accumulate, and are highly toxic, can cause serious environmental pollution and harm human health. Therefore, dyeing and printing wastewater must be purified before discharge. Common purification methods include photocatalytic degradation, membrane separation, electrochemical degradation, and biological methods. However, these methods suffer from high energy consumption, high costs, and low efficiency. Adsorption is another method for purifying dyeing and printing wastewater, widely used due to its flexible design, ease of operation, low cost, high removal efficiency, and wide applicability. Adsorbents used in adsorption are generally divided into three categories in industry: oxygen-containing compounds (such as silica gel), carbon-based materials (such as activated carbon), and polymeric adsorbents. The hydrophilicity and polarity of oxygen-containing compound adsorbents enhance the interaction between the adsorbent and the pollutant, thereby removing dyes. Carbon-based adsorbents utilize the large surface area provided by their porous structure to remove dyes. Polymeric adsorbents are composite materials containing polar and non-polar components within a porous polymer matrix and are often used for adsorbing organic dyes. However, current adsorbents still suffer from complex preparation methods, secondary pollution during the preparation process, poor dye removal performance, limited dye removal types, or difficulty in recycling after dye removal. Therefore, developing new adsorbents with strong dye removal capabilities, a wide range of dye removal types, easy recycling after dye removal, while also ensuring a simple preparation method and no secondary pollution during the preparation process remains a challenge to be solved. Summary of the Invention

[0003] In response to the shortcomings and drawbacks of existing technologies, the primary objective of the present invention is to provide a method for preparing a broad-spectrum anionic dye adsorbent. This adsorbent has a simple preparation process, requiring no heating and can be prepared in a single step. The preparation process produces no pollutants and causes no secondary pollution. The product does not require further cleaning or purification, and can be used directly after drying. No special equipment is required for preparation. This method addresses the complex and lengthy preparation process of conventional adsorbents. It also offers low investment costs, strong practicality, and ease of industrialization.

[0004] Another object of the present invention is to provide a polyethyleneimine / sodium alginate (PEI / SA) adsorbent prepared using the above-described method, which has high adsorption capacity for a broad spectrum of anionic dyes. This adsorbent is broad-spectrum, capable of adsorbing a variety of anionic dyes, exhibits high adsorption capacity and adsorption efficiency, is biodegradable, and is recyclable.

[0005] Another object of the present application is to provide the use of the PEI / SA adsorbent as described above, which can adsorb various anionic dyes.

[0006] The object of the present application is achieved by the following technical solutions:

[0007] In a first aspect, a method for preparing a broad-spectrum anionic dye adsorbent comprises the following steps:

[0008] S1: Dissolve PEI and SA in water at ambient temperature, stir until uniform, to obtain a PEI / SA solution;

[0009] S2: Add polyether to the PEI / SA solution prepared in S1, stir until uniform, to obtain a PEI / SA / polyether solution;

[0010] S3: Place the PEI / SA / polyether solution prepared in S2 at ambient temperature to obtain a PEI / SA / polyether gel (referred to as PEI / SA gel);

[0011] S4: Freeze-dry the gel prepared in S3 to obtain a PEI / SA adsorbent;

[0012] S5: Cut the product obtained in S4 into pieces (particle size about 1 mm).

[0013] In S1, the concentration of PEI is 1-5%, preferably 5%.

[0014] In S1, the weight average molecular weight of PEI is 300-70000.

[0015] In S1, the concentration of SA is 1-5%, preferably 3%.

[0016] In S1, the mass ratio of PEI / SA is 1:1, 1:3, 1:5, 3:3, 5:3, preferably 5:3.

[0017] In S1, the preparation temperature of PEI / SA is ambient temperature, and the stirring time is 30 min.

[0018] In S2, the amount of polyether is 1 times, 1.5 times, 2 times of PEI, preferably 2 times of PEI.

[0019] In S2, the preparation temperature is ambient temperature, and the stirring time is 10 min.

[0020] In S3, the standing time is 1 h, 3 h, 5 h, 7 h; preferably 5 h.

[0021] In S4, the freeze-drying time is 24 h.

[0022] In said S5, the obtained product is chopped into particles with a diameter not exceeding 1 mm, preferably 0.5 mm.

[0023] In a second aspect, an anionic dye adsorbent prepared by the above preparation method is a polyethyleneimine / sodium alginate (PEI / SA) adsorbent containing polyethyleneimine (PEI), sodium alginate (SA) and polyether.

[0024] Thirdly, the adsorbent is used for adsorption of anionic dyes, including Congo Red (CR), Amido Black 10B (AB-10B), Acid Blue 25 (AB-25), Acid Fuchsin (AF), Methyl Orange, Acid Green 25, Sunset Yellow, Indigo Carmine, Alizarin Red S, Direct Red 7, Taitan Yellow, Methyl Blue, etc.

[0025] The present invention has the following advantages and effects compared to the prior art:

[0026] (1) The present invention provides a novel broad-spectrum anionic dye adsorbent PEI / SA, which can adsorb a variety of anionic dyes, has a large adsorption capacity, high adsorption rate, is biodegradable, and can be recycled.

[0027] (2) The present invention provides a process for preparing the PEI / SA adsorbent. This process is simple, and the product preparation is completed in one step without heating. No pollutants are emitted during the preparation process. The product does not require further cleaning or purification, and can be used directly after drying. No special equipment is required for product preparation. This solves the problem of the traditional adsorbent preparation process being complex and lengthy. The process has low investment costs, strong practicality, and is easily commercializable.

[0028] (3) The PEI / SA adsorbent provided by the present invention can adsorb a variety of anionic dyes, including Congo red (CR), amino black 10B (AB-10B), acid blue 25 (AB-25), acid fuchsin (AF), methyl orange, acid green 25, sunset yellow, indigo carmine, alizarin red S, direct red 7, tatanium yellow, methyl blue, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Example 1 is a flow chart for preparing PEI / SA adsorbent.

[0030] Figure 2 Comparison of PEI / SA adsorbent before and after adsorption of different anionic and cationic dyes.

[0031] Figure 3 The adsorption capacity and removal rate results of the adsorbent prepared in Example 1 after being recycled 6 times. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the accompanying drawings.

[0033] In the following examples, unless otherwise mentioned, the materials or reagents used are conventional commercial products, and the operations used are conventional technical operations.

[0034] Example 1 Preparation of PEI / SA adsorbent

[0035] (1) PEI was added to water and stirred to obtain a 5% PEI solution. 1% SA was then added to the PEI solution and stirred for 30 min to completely dissolve the SA, thereby obtaining a PEI / SA mixed solution A, in which the mass ratio of PEI to SA was 5:1.

[0036] (2) Add polyethylene glycol diglycidyl ether to solution A and stir for 10 min to obtain PEI / SA / polyether solution B. The mass ratio of PEI, SA and polyethylene glycol diglycidyl ether is 5:1:10.

[0037] (3) Pour the mixed solution B into a polytetrafluoroethylene mold (10 cm × 10 cm), let it stand at room temperature for 5 h, and then demold to obtain the PEI / SA gel.

[0038] (4) Freeze-dry the gel obtained in step 3 for 24 h.

[0039] (5) The obtained material is chopped into pieces with a diameter not exceeding 1 mm.

[0040] Figure 1 This is the flow chart of adsorbent preparation.

[0041] Example 2 Preparation of PEI / SA adsorbent

[0042] Compared with Example 1, the main difference is that the PEI / SA mass ratio is different, specifically:

[0043] (1) PEI was added to water and stirred to obtain a 5% PEI solution. 3% SA was then added to the PEI solution and stirred for 30 min to completely dissolve the SA, thereby obtaining a PEI / SA mixed solution A, in which the mass ratio of PEI to SA was 5:3.

[0044] (2) Add polyethylene glycol diglycidyl ether to solution A and stir for 10 min to obtain PEI / SA / polyether solution B. The mass ratio of PEI, SA and polyethylene glycol diglycidyl ether is 5:3:10.

[0045] (3) Pour the mixed solution B into a polytetrafluoroethylene mold (10 cm × 10 cm), let it stand at room temperature for 5 h, and then demold to obtain the PEI / SA gel.

[0046] (4) Freeze-dry the gel obtained in step 3 for 24 h.

[0047] (5) The obtained material is chopped into pieces with a diameter not exceeding 1 mm.

[0048] Example 3 Preparation of PEI / SA adsorbent

[0049] Compared with Example 2, the main difference is that the PEI / SA adsorbent is made into a membrane, specifically:

[0050] (1) PEI was added to water and stirred to obtain a 5% PEI solution. 3% SA was then added to the PEI solution and stirred for 30 min to completely dissolve the SA, thereby obtaining a PEI / SA mixed solution A, in which the mass ratio of PEI to SA was 5:3.

[0051] (2) Add polyethylene glycol diglycidyl ether to solution A and stir for 10 min to obtain PEI / SA / polyether solution B. The mass ratio of SA, PEI and polyethylene glycol diglycidyl ether is 5:3:10.

[0052] (3) Pour the mixed solution B into a polytetrafluoroethylene mold (10 cm × 10 cm), let it stand at room temperature for 5 h, and then demold to obtain the PEI / SA gel.

[0053] (4) The gel obtained in step 3 was freeze-dried to obtain a 10 cm × 10 cm × 0.12 cm gel.

[0054] Example 4: Adsorption of CR Anionic Dyes by PEI / SA Adsorbent

[0055] The adsorbent prepared in Example 1 was used to adsorb CR. 0.025 g of the adsorbent was added to 50 mL of a CR dye solution with an initial concentration of 1700 mg / L. The solution was shaken on a constant temperature shaker at 30°C, 200 rpm, and a pH of 3 for 24 hours. After shaking, the adsorption capacity and adsorption rate were calculated. Adsorption capacity = (pre-adsorption concentration - post-adsorption concentration) × dye solution volume / adsorbent dosage; adsorption rate = (pre-adsorption concentration - post-adsorption concentration) / pre-adsorption concentration. Calculations show that when the adsorption rate is above 90%, 2861.93 mg / g of CR dye can be adsorbed.

[0056] Figure 2 a1 in the figure is the picture before the dye solution is adsorbed. Figure 2 a2 in the figure is the picture after 24 h of adsorption.

[0057] Example 5 PEI / SA adsorbent adsorbs AB-10B anionic ionic dye

[0058] AB-10B was adsorbed with the adsorbent prepared in Example 1. 0.025 g of the adsorbent was placed in a 50 mL AB-10B dye solution with an initial concentration of 750 mg / L, and shaken in a constant-temperature shaker at 30°C, 200 r / min, and pH 3 for 24 h. After the shaking was completed, the adsorption amount and the adsorption rate were calculated, respectively. The adsorption amount = (pre-adsorption concentration - post-adsorption concentration) x dye solution volume / adsorbent amount; the adsorption rate = (pre-adsorption concentration - post-adsorption concentration) / pre-adsorption concentration. It was calculated that when the adsorption rate was 90% or more, 1368.08 mg / g of AB-10B dye could be adsorbed.

[0059] Figure 2 b1 in FIG. is a graph before adsorption of the dye solution, Figure 2 b2 in FIG. is a graph after 24 h of adsorption.

[0060] Example 6 PEI / SA adsorbent adsorbs AB-25 anionic ionic dye

[0061] AB-25 was adsorbed with the adsorbent prepared in Example 2. 0.025 g of the adsorbent was placed in a 50 mL AB-25 dye solution with an initial concentration of 2300 mg / L, and shaken in a constant-temperature shaker at 30°C, 200 r / min, and pH 3 for 24 h. After the shaking was completed, the adsorption amount and the adsorption rate were calculated, respectively. The adsorption amount = (pre-adsorption concentration - post-adsorption concentration) x dye solution volume / adsorbent amount; the adsorption rate = (pre-adsorption concentration - post-adsorption concentration) / pre-adsorption concentration. It was calculated that when the adsorption rate was 90% or more, 4233.99 mg / g of AB-25 dye could be adsorbed.

[0062] Figure 2 c1 in FIG. is a graph before adsorption of the dye solution, Figure 2 c2 in FIG. is a graph after 24 h of adsorption.

[0063] Example 7 PEI / SA adsorbent adsorbs AF anionic ionic dye

[0064] AF was adsorbed using the adsorbent prepared in Example 2. 0.025 g of the adsorbent was added to 50 mL of an AF dye solution with an initial concentration of 800 mg / L. The solution was shaken on a constant temperature shaker at 30°C, 200 rpm, and a pH of 3 for 24 hours. After shaking, the adsorption capacity and adsorption rate were calculated. Adsorption capacity = (pre-adsorption concentration - post-adsorption concentration) × dye solution volume / adsorbent dosage; adsorption rate = (pre-adsorption concentration - post-adsorption concentration) / pre-adsorption concentration. Calculations show that when the adsorption rate is above 90%, 1561.38 mg / g of AF dye can be adsorbed.

[0065] Figure 2 The d1 in the figure is the figure before the dye solution is adsorbed. Figure 2 The d2 in the figure is the graph after 24 h of adsorption.

[0066] Example 8 Recyclability of PEI / SA adsorbent

[0067] The PEI / SA adsorbent prepared in Example 1 was added to aqueous solutions of CR, AB-10B, AB-25, and AF, respectively. The PEI / SA adsorbent dosage was fixed at 0.5 g / L, the adsorption temperature was 30°C, the initial dye solution concentration was 100 mg / L, and the pH of the solution was adjusted to 3. Adsorption was performed in a thermostatic oscillator at 200 r / min for 24 hours. After six cycles of use, the dye removal efficiency remained as high as 99.8%.

[0068] Figure 3 This is a graph of the adsorption capacity and removal rate of the adsorbent PEI / SA after it was recycled 6 times.

[0069] Example 9 Biodegradability of PEI / SA Adsorbent

[0070] The PEI / SA membrane prepared in Example 3 was cut into 1 cm × 1 cm membrane samples and buried in soil at a depth of 15 cm for 6 months. During the experiment, the soil was kept moist by sprinkling water daily, except on rainy days. Samples were removed every 2 months, cleaned of soil from the surface, rinsed repeatedly with distilled water, and freeze-dried to constant weight. The degradation rate was calculated as follows: Degradation rate = (sample weight after degradation / sample weight before degradation) × 100%. The experimental results showed that the PEI / SA adsorbent was completely degraded after 6 months.

[0071] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a broad-spectrum anionic dye adsorbent, characterized in that: The following steps are involved: S1: At room temperature, dissolving polyethyleneimine and sodium alginate in water and stirring uniformly to obtain a PEI / SA solution; the mass fraction of polyethyleneimine in the PEI / SA solution is 1-5%, and the mass fraction of sodium alginate is 1-5%; the weight average molecular weight of the polyethyleneimine is 300-70,000; S2: adding polyether to the PEI / SA solution prepared in S1 and stirring uniformly to obtain a PEI / SA / polyether solution; the polyether is polyethylene glycol diglycidyl ether, and the amount used is 1 times, 1.5 times or 2 times that of PEI; S3: at ambient temperature, allowing the PEI / SA / polyether solution prepared in S2 to stand to obtain a PEI / SA / polyether gel, i.e., a PEI / SA gel; S4: freeze-drying the PEI / SA gel prepared in S3 to obtain a PEI / SA adsorbent.

2. The preparation method according to claim 1, wherein: In the PEI / SA solution, the mass ratio of polyethyleneimine to sodium alginate is 1:1, 1:3, 1:5, 3:3 or 5:

3.

3. The preparation method according to claim 2, wherein: In the PEI / SA solution, the mass ratio of polyethyleneimine to sodium alginate is 5:

3.

4. The preparation method according to claim 1, wherein: In S3, the standing time is 1 h, 3 h, 5 h or 7 h.

5. The preparation method according to claim 1, wherein: In S4, the freeze-drying time is 24 h.

6. A broad-spectrum anionic dye adsorbent prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the adsorbent according to claim 6 in the adsorption of anionic dyes.

8. The use according to claim 7, characterized in that: The anions include Congo red, amido black 10B, acid blue 25, acid fuchsin, methyl orange, acid green 25, sunset yellow, indigo carmine, alizarin red S, direct red 7, tatanium yellow, and methyl blue.

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