Potato starch beta-cyclodextrin composite nano sponge as well as preparation method and application thereof

Abstract

The invention relates to potato starch beta-cyclodextrin composite nano sponge as well as a preparation method and application thereof, and belongs to the field of chemical materials. The composite nano sponge is prepared by compounding beta-cyclodextrin, potato starch, chitosan and polyethyleneimine according to a mass ratio of 2.5: 2.08: 1: 2.5. The preparation method comprises the following steps: preparing polyethyleneimine into a solution, reacting with beta-cyclodextrin and epichlorohydrin, then blending with a potato starch solution subjected to alkali treatment and a chitosan mixed solution, dropwise adding into a melamine sulfate solution, molding, and freeze-drying. The nano sponge has a three-dimensional porous structure, the maximum adsorption capacities of the nano sponge to rare earth ions (such as Ce < 3 + > and Ho < 3 + >) respectively reach 143.7 mg / g and 145.78 mg / g, the selective removal rate in a mixed solution containing various competitive ions exceeds 82.12%, and the recovery efficiency of rare earth in industrial wastewater is higher than 93.76%. After five times of circulation, the removal rate is still maintained to be 71.48% or above, and the desorption rate exceeds 90.09%. The method has the advantages of green and cheap raw materials and simple process, and has significant application value in the field of rare earth resource recovery.

Description

Technical Field

[0001] The present invention belongs to the field of chemical materials and relates to potato starch β-cyclodextrin composite nanosponges, their preparation methods and applications Background Art

[0002] Rare earth elements (REEs) are key components of modern technological products and play an important role in strategic emerging industries such as new energy vehicles, electronic information, aerospace, national defense and high-end equipment manufacturing. They are indispensable core basic materials and are called the industrial vitamins. For example, cerium (Ce) is an abundant light rare earth (LREE) and has been used in the manufacture of various technological products. Ho belongs to one of the heavy rare earths (HREEs) and has been applied to various high-tech industries such as lasers, high-performance permanent magnets, fluorescent lamps, etc. due to its rarity and uniqueness. China's rare earth production accounts for 80% of the global production. However, due to the difficult mining, complex production technology and being troubled by environmental risks, rare earths are still in a state of imbalance between supply and demand in the international community. In addition, during the rare earth mining process, untreated industrial wastewater can harm the surrounding water, soil resources, ecological environment and even human health. Therefore, recovering rare earths from industrial wastewater can not only improve environmental pollution problems but also increase the recycling of rare earth resources

[0003] The adsorption method has the advantages of convenient operation, strong adaptability, wide application range, environmental friendliness, etc. and is an effective method for rare earth recovery. Bio-based materials are the preferred green materials in the current adsorption method and have great advantages in terms of renewability, environmental protection and post-treatment. Starch is the most abundant polysaccharide in nature. It has many oxygen-containing groups such as hydroxyl groups and ether bonds on its surface and also has excellent properties such as biodegradability, biocompatibility and non-toxicity. Thus, it is widely used in adsorption. However, natural starch is prone to degradation, resulting in its low adsorption performance and restricting its application in adsorption materials

[0004] Cyclodextrin nanosponges (CDNSs) are a new type of functional nanomaterial constructed based on cyclodextrin and its derivatives and cross-linking agents. They have hydrophilicity and a three-dimensional network structure and have high stability in a relatively high temperature and a large pH range. Now they have been applied as a new type of adsorbent for the removal of heavy metal ions, dyes, drug molecules, etc. in wastewater

[0005] The invention with the publication number CN116836547A discloses a polyethyleneimine / β-cyclodextrin nanocomposite material and its application in the preparation of nanofiltration membranes. The nanofiltration membrane induced by the synergistic effect of polyethyleneimine / β-cyclodextrin optimizes the permeability-selectivity of traditional membrane materials and can achieve the selective retention and removal of divalent salt ions. However, limited by the disadvantage of fewer adsorption sites of cyclodextrin nanosponges, the efficiency of cyclodextrin nanosponges in the recovery of rare earths from industrial wastewater is low. In order to expand the application scope of cyclodextrin nanosponges, new cyclodextrin nanosponge materials are urgently needed to be developed. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a potato starch β-cyclodextrin composite nanosponge, its preparation method and application.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a potato starch β-cyclodextrin composite nanosponge, which is composed of β-cyclodextrin (β-CD), potato starch (PCPP), chitosan (CS), and polyethyleneimine (PEI), and their mass ratio is: β-cyclodextrin (β-CD): potato starch (PCPP): chitosan (CS): polyethyleneimine (PEI) = 2.5:2.08:1:2.5;

[0009] Furthermore, the present invention provides a preparation method of a potato starch β-cyclodextrin composite nanosponge, and the method includes the following steps:

[0010] (1) Dissolve polyethyleneimine (PEI) in deionized water to prepare a PEI solution;

[0011] (2) In an alkaline solution, add β-cyclodextrin (β-CD) and epichlorohydrin (ECH), stir and react, and then add the PEI solution prepared in step (1) to prepare a β-CD@PEI solution;

[0012] (3) Dissolve PS in deionized water to form a PS solution, add a sodium hydroxide solution and stir rapidly to prepare a transparent gelatinous liquid;

[0013] (4) Mix chitosan (CS) and polyethylene glycol (PCS) in a certain proportion and dissolve them in deionized water, add acetic acid and stir, and then add a citric acid solution to prepare a viscous solution;

[0014] (5) Mix the three mixed solutions prepared in steps (2), (3) and (4), stir at room temperature, then drop into the melamine sulfate solution (STTP) to form bead-like materials, soak overnight, and freeze-dry to obtain potato starch β-cyclodextrin composite nanosponges (β-CD@PCPP NSs);

[0015] Preferably, in step (1), the solid-liquid ratio of the polyethyleneimine (PEI) to deionized water is 1:10 (g:mL);

[0016] Preferably, in step (2), the alkaline solution is a 5% NaOH solution, and the mass ratio of β-cyclodextrin (β-CD) to epichlorohydrin (ECH) is 3:6;

[0017] Preferably, in step (3), the solid-liquid ratio of the PS to deionized water is 1:3, and the concentration of the sodium hydroxide solution is 50%;

[0018] Preferably, in step (4), the mass ratio of the chitosan (CS) to the polyethylene glycol (PCS) is 3:1, the citric acid solution is 15%, and the reaction conditions are reaction at 80 °C for 3 h;

[0019] Preferably, in step (5), the mixing ratio of the three mixed solutions is: 1:1:1.5, the concentration of the dropped melamine sulfate solution (STTP) is 1%, and the pH is 8.5.

[0020] Application of potato starch β-cyclodextrin composite nanosponges (β-CD@PCPP NSs) in the field of recovering rare earth ions from industrial wastewater.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The present invention selects cheap and green β-CD, PCPP, PEI and CS as raw materials, and prepares β-cyclodextrin potato starch composite nanosponges β-CD@PCPP NSs based on the method of material compounding. The preparation method of the nanosponges is simple and the cost is low;

[0023] 2. The adsorption capacities of β-CD@PCPP NSs for Ce 3+ and Ho 3+ are 143.7 and 145.78 mg / g respectively, showing a relatively high adsorption capacity;

[0024] 3. In the mixed solution containing rare earth ions and various competing ions, the removal rates of β-CD@PCPP NSs for Ce 3+ and Tb 3+ are 82.12% and 86.20% respectively, while those of other metal ions are all less than 10.70%, indicating that β-CD@PCPP NSs has high adsorption performance;

[0025] 4. The removal rate of β-CD@PCPP NSs is still greater than 71.48% in 5 adsorption-desorption cycles, while the desorption rate is higher than 90.09%. This indicates that β-CD@PCPP NSs have good cyclic regeneration ability;

[0026] 5. The removal rate of β-CD@PCPP NSs for RE ions in industrial wastewater is higher than 93.76%, while the adsorption rate for competitive ions does not exceed 8.0%. This indicates that β-CD@PCPP NSs have potential application prospects for the recovery of rare earth ions in industrial wastewater.

[0027] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in preferred detail below in conjunction with the drawings, where:

[0029] Figure 1 is the scanning electron microscope characterization of β-CD@PCPP NSs;

[0030] Figure 2 is the energy dispersive X-ray spectroscopy characterization of β-CD@PCPP NSs;

[0031] Figure 3 is the adsorption study of β-CD@PCPP NSs for Ce 3+ and Tb 3+ respectively;

[0032] Figure 4 is the recovery study of β-CD@PCPP NSs for RE ions in industrial wastewater;

[0033] Figure 5 is the cyclic regeneration performance study of β-CD-PVA / PCS NSs, (a) adsorption diagram, (b) desorption diagram. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0035] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0036] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] Example 1

[0038] Preparation of potato starch β-cyclodextrin composite nanosponge:

[0039] (1) Dissolve 1 g of PEI in 10 mL of deionized water. Add 3 g of β-CD to a 5% NaOH solution, and then add 6% of ECH and react at 40 °C for 45 min. Then add the same volume of the PEI solution and keep the same temperature and continue to react for 2 h to obtain the β-CD@PEI solution.

[0040] (2) Dissolve 3 g of PS in deionized water to obtain a PS solution. After stirring at 55 °C for 0.5 h, add 0.25 mL of 50% NaOH solution thereto, and quickly stir for 10 min to obtain a transparent colloidal liquid.

[0041] (3) Mix 2.5 g of CS and PCS in a ratio of 3:1 and put them into deionized water. Then add acetic acid and stir at room temperature for 30 min to prepare a viscous solution with a certain concentration. Then add a citric acid solution (15%), and react at 80 °C for 3 h. Mix the above three mixed solutions in a certain ratio and stir at room temperature for 0.5 h. Then drop it into a STTP (1%, pH 8.5) solution at a speed of 1 drop per second to form bead-like materials, and soak overnight in it. Freeze the obtained bead-like materials at -18 °C for 16 - 24 h, and then freeze-dry to obtain nano-sponge β-CD@PCPP.

[0042] Example 2

[0043] Characterization of β-CD-PVA / PCS NSs

[0044] (1) Scanning electron microscope characterization

[0045] The cross-sectional morphology of β-CD@PCPP NSs was studied by using a scanning electron microscope (SEM). As Figure 1 shown, β-CD@PCPP NSs have a large number of unevenly distributed microporous structures inside. These pores provide a certain guarantee for the mechanical properties of the adsorbent and also provide a good basis for adsorbing RE ions in water. Figure 1 Scanning electron microscope characterization of β-CD@PCPP NSs

[0046] (2) Energy-dispersive X-ray spectroscopy characterization

[0047] The elemental distribution and elemental composition of β-CD@PCPP NSs were analyzed by using energy-dispersive X-ray spectroscopy (EDS). As Figure 2 shown, the distribution and percentage of carbon (C), oxygen (O), nitrogen (N), and phosphorus (P) elements in the detected sample were detected. The detection results show that the C, O, N, and P elements are evenly distributed, and the total content of oxygen, nitrogen, and phosphorus elements is close to 80%. The high content of these elements also proves the extensive distribution of active sites in the material, providing evidence for the phenomenon of high adsorption capacity in subsequent adsorption experiments. Figure 2 Energy-dispersive X-ray spectroscopy characterization of β-CD@PCPP NSs

[0048] Example 3

[0049] Adsorption application of β-CD@PCPP NSs for rare earth ions:

[0050] Dissolve rare earth nitrate hexahydrate in distilled water respectively to prepare a 1000 mg / L stock solution. Dilute the stock solution to obtain working solutions with different concentrations. Mix the adsorbent with the rare earth ion solution for 4 - 12 hours, and study the maximum adsorption capacity and selective adsorption performance of β-CD@PCPP NSs for Ce 3+ and Ho 3+ at different concentrations (50 - 250 mg / L), and study its ability to recover rare earth ions from industrial wastewater.

[0051] The maximum adsorption capacity for Ce 3+ and Ho 3+ is shown as Figure 3 . The experimental results show that the adsorption amounts of β-CD@PCPP NSs for Ce 3+ and Tb 3+ are 143.7 and 145.78 mg / g respectively.

[0052] Figure 3 Adsorption studies of β-CD@PCPP NSs for Ce 3+ and Tb 3+ respectively. (Conditions: 25 °C; pH = 6.5; Cinitial = 15 - 250 mg / L)

[0053] The ability of β-CD@PCPP NSs to recover rare earth ions from industrial wastewater is shown as Figure 4 . The removal rate of β-CD@PCPP NSs for RE ions is higher than 98.83%, while the adsorption rate for competing ions does not exceed 8.31%.

[0054] Figure 4 Recovery study of β-CD@PCPP NSs for RE ions from industrial wastewater.

[0055] To study the reusability of β-CD@PCPP NSs, add 25 mg of the adsorbent into 10 mL of a rare earth ion solution containing 50 mg / L of Ce 3+ and Ho 3+ , and oscillate at 25 °C and 120 r / min for 4 h. Use 0.05 mol / L hydrochloric acid as the eluent, place the adsorbed adsorbent in the eluent for desorption for 4 h, and repeat the above adsorption-desorption operation 5 times. The results of its cyclic regeneration are shown in Figure 5 . After 5 cycles, the removal rate of β-CD@PCPP NSs for RE ions is still greater than 71.48%, while the desorption rate is higher than 90.09%. Figure 5 Study on the cyclic regeneration performance of β-CD-PVA / PCS NSs, (a) adsorption diagram, (b) desorption diagram.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. Potato starch β-cyclodextrin composite nano sponge, characterized in that: The potato starch β-cyclodextrin composite nano sponge is composed of β-cyclodextrin (β-CD), potato starch (PCPP), chitosan (CS), and polyethyleneimine (PEI), and the mass ratio thereof is: β-cyclodextrin (β-CD): potato starch (PCPP): chitosan (CS): polyethyleneimine (PEI) = 2.5:2.08:1:2.

5.

2. The method for preparing the potato starch β-cyclodextrin composite nano sponge according to claim 1, characterized in that: The method comprises the following steps: (1) dissolving polyethyleneimine (PEI) in deionized water to prepare a PEI solution; (2) adding β-cyclodextrin (β-CD) and epichlorohydrin (ECH) to an alkaline solution, stirring for reaction, and then adding the PEI solution prepared in step (1) to prepare a β-CD@PEI solution; (3) dissolving PS in deionized water to form a PS solution, adding sodium hydroxide solution and rapidly stirring to prepare a transparent colloidal liquid; (4) chitosan (CS) and polyethylene glycol (PCS) are mixed in a certain ratio and dissolved in deionized water, acetic acid is added and stirred, and then citric acid solution is added to prepare a viscous solution; (5) The three mixed solutions prepared in steps (2), (3) and (4) are mixed, stirred at room temperature, and then dropped into a melamine sulfate solution (STTP) to form a beaded material, which is then soaked overnight and freeze-dried to prepare a potato starch β-cyclodextrin composite nanosponge (β-CD@PCPP NSs).

3. The method according to claim 2, characterized in that The solid-to-liquid ratio of polyethyleneimine (PEI) to deionized water in step (1) is 1:10 (g:mL).

4. The method according to claim 2, characterized in that: In step (2), the alkaline solution is a 5% NaOH solution, and the mass ratio of β-cyclodextrin (β-CD) to epichlorohydrin (ECH) is 3:

6.

5. The method according to claim 2, characterized in that: In step (3), the solid-to-liquid ratio of PS to deionized water is 1:3, and the concentration of the sodium hydroxide solution is 50%.

6. The method according to claim 2, characterized in that In step (4), the mass ratio of chitosan (CS) to polyethylene glycol (PCS) is 3:1, the citric acid solution is 15%, and the reaction conditions are 80° C. for 3 hours.

7. The method according to claim 2, characterized in that The mixing ratio of the three mixed solutions in step (5) is 1:1:1.5, the concentration of the added melamine sulfate solution (STTP) is 1%, and the pH value is 8.

5.

8. Application of potato starch β-cyclodextrin composite nanosponge (β-CD@PCPP NSs) prepared by the method according to any one of claims 1 to 7 in the field of recovering rare earth ions from industrial wastewater.

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