A magnetic foaming freeze-dried modified chitosan material and its preparation method and application

Abstract

The present invention discloses a magnetic foaming, freeze-dried, modified chitosan material, its preparation method, and application, and belongs to the field of groundwater treatment in coal mine areas. The present invention combines modification with ferrosoferric oxide, foaming modification with sodium dodecylsulfonate, and flash freezing modification to obtain a magnetic foaming, freeze-dried, modified chitosan material. The chitosan material is a modified chitosan microsphere structure suitable for adsorbing mine water pollutants. The chitosan microsphere is stable in neutral, alkaline, and high-salt mine water solutions, and has a good ability to remove metal ions such as iron, manganese, and calcium from mine water.

Description

Technical Field

[0001] The invention belongs to the field of underground water treatment in coal mine areas, and particularly relates to a magnetic foaming freeze-dried modified chitosan material and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Mine water contains significant amounts of harmful heavy metals, contributing to water pollution during coal mining and utilization. Currently, groundwater pollution in coal mining areas is primarily addressed through a combination of blocking and treatment. Blocking involves using impermeable materials to seal underground water bodies in mining areas, preventing the spread of contaminated water. Treatment methods primarily include physical adsorption, chemical treatment, thermal treatment, and membrane separation. The physical adsorption method uses zeolite, activated alumina, activated carbon, resin and other adsorbents to absorb heavy metal ions in sewage to achieve the purpose of reducing pollutants, but these adsorbents have low adsorption capacity, limited raw material sources, high prices, and high carbon emissions, making it difficult to effectively remove pollutants; the chemical method removes salt from mine water by chemically reacting with ions in the mine water. The overall cost is high, and it is very expensive to remove highly mineralized mine water; the thermal method uses distillation to separate salt from water in mine water, thereby achieving the purpose of desalination, but the evaporation device of this method is extremely prone to scaling, and the initial investment and energy consumption costs are high, so it is only suitable for areas with sufficient thermal energy conditions; the membrane separation method is to pressurize the sewage and remove inorganic salt ions in the water through the separation membrane. This method is difficult to work for open underground mine sewage.

[0004] As a highly effective physical adsorption material, chitosan, with its many advantages such as inherent non-toxicity, high efficiency, and biodegradability, has attracted widespread attention. Common types of chitosan available on the market include chitosan, carboxymethyl chitosan, hydroxymethyl chitosan, and water-soluble chitosan. Currently, research on common chitosan materials focuses primarily on chemical modification of chitosan by replacing surface groups or adding complex substances. Limited research has been conducted on functional hybridization of chitosan, with most studies focusing on the preparation of modified chitosan membrane structures. This approach is relatively limited, resulting in chitosan failing to fully utilize its inherent adsorption properties and application potential. Summary of the Invention

[0005] To address the deficiencies of the prior art, the present invention provides a magnetic foaming freeze-dried modified chitosan material, its preparation method, and its application. The magnetic foaming freeze-dried modified chitosan material is prepared from ferroferric oxide, sodium dodecyl sulfate, and chitosan through freeze-drying and modification. It is stable in neutral, alkaline, and high-salt mine water solutions and has a good ability to remove metal ions such as iron, manganese, and calcium from mine water. The material is a modified chitosan microsphere suitable for adsorbing mine water pollutants.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, the present invention provides a magnetic foaming freeze-dried modified chitosan material, wherein the magnetic foaming freeze-dried modified chitosan material is a porous microsphere structure, wherein ferrosoferric oxide particles are uniformly distributed on the porous microsphere structure;

[0008] In parts by weight, the magnetic foaming freeze-dried modified chitosan material comprises: 0.1-1 parts of ferrosoferric oxide, 1.2-2 parts of chitosan, and 0.01-0.05 parts of sodium dodecyl sulfate.

[0009] Furthermore, based on weight, 0.1-0.5 parts of ferrosoferric oxide, 1.4-1.6 parts of chitosan, and 0.01-0.02 parts of sodium lauryl sulfate are included.

[0010] The particle size of the microspheres is 2-2.5 mm, and the average particle size of the pores is 100-200 μm.

[0011] The principle of magnetic foaming freeze-dried modified chitosan material adsorbing heavy metal pollutants is that its macromolecules contain a large number of amino and hydroxyl groups. The lone pair of electrons on the nitrogen atom can be invested in the empty orbit of the metal ion to form a coordination bond, so that the amino, hydroxyl and heavy metal ions form a stable cyclic chelate, thereby solidifying the heavy metal pollution source and achieving the purpose of reducing mine water pollutants.

[0012] In a second aspect, the present invention provides a method for preparing a magnetic foaming freeze-dried modified chitosan material, comprising the following steps:

[0013] S1: dissolving ferroferric oxide, chitosan and sodium dodecyl sulfate in an acid solution to prepare a magnetic foaming chitosan acid solution;

[0014] S2: dripping the magnetic foamed chitosan acid solution into an alkaline coagulation solution to obtain a coagulated magnetic foamed chitosan hydrogel, and then performing aging, washing, cross-linking polymerization, and freeze-drying to obtain the result.

[0015] Sodium lauryl sulfate is used as a foam stabilizer. A foam stabilizer is a surfactant that increases the surface tension of liquids, thereby prolonging and stabilizing foam and maintaining long-term performance.

[0016] In one or more embodiments, ferrosoferric oxide is a nano ferrosoferric oxide powder having a particle size of 100 to 500 nm, preferably 100 to 200 nm. Since chitosan itself has the ability to complex and adsorb iron ions, if the iron source is a substance such as ferrous chloride, new impurities will be introduced, resulting in a decrease in the product's ability to adsorb iron ions. In addition, if ferrosoferric oxide is simply added, ferrosoferric oxide and chitosan will be mixed, and after drying, a dense chitosan-ferrosoferric oxide sphere will be obtained, in which ferrosoferric oxide aggregates into balls, greatly reducing the adsorption effect. In the present invention, ferrosoferric oxide exists in the form of microspheres, and the microspheres do not dissolve in chitosan.

[0017] In one or more embodiments, the chitosan is a 2-2.5 mm dark grey lightweight sphere.

[0018] In one or more embodiments, the acid is acetic acid, and the mass concentration of the acid solution is 2-3 wt.%, preferably 2.5 wt.%. Chitosan is a polymer compound that is insoluble in water, alkali, and organic solutions, but because it contains amino groups, it can form salts with acid solutions.

[0019] In one or more embodiments, in parts by weight, 0.1-1 parts of ferrosoferric oxide, 1.2-2 parts of chitosan, 0.01-0.05 parts of sodium lauryl sulfate, and 40-60 parts of acid solution are used, preferably 0.1-0.5 parts of ferrosoferric oxide, 1.4-1.6 parts of chitosan, 0.01-0.02 parts of sodium lauryl sulfate, and 40-50 parts of acid solution.

[0020] In one or more embodiments, in step S1, stirring is performed at 50-70° C. until all the components are dissolved.

[0021] In one or more embodiments, in step S2, the alkaline coagulation liquid is a mixture of alkali and water, wherein the alkali is a strong alkali, such as sodium hydroxide. Weak alkali is not conducive to coagulation. The mass ratio of alkali to water is (2-6):(40-60).

[0022] In one or more embodiments, in step S2, the alkali coagulation liquid is prepared by dissolving alkali in water to obtain an alkali aqueous solution, stirring the solution until no alkali solid is left, and waiting for coagulation at room temperature.

[0023] In one or more embodiments, in step S2, the dripping method is to use an injection dripping method, specifically: fix the syringe that absorbs the magnetic foamed chitosan acid solution on the triple micro-injection pump, put the dispensing plastic injection needle on the syringe head, adjust the height of the test bench below the micro-injection pump until the center position of the syringe needle is 5~20 cm above the liquid level, advance the syringe at a propulsion speed of 1~3 μL / min, and drip the solution into the prepared alkaline coagulant solution.

[0024] In one or more embodiments, in step S2, small amounts of dripping are used multiple times.

[0025] In one or more embodiments, the aging is to place the solidified magnetic foamed chitosan hydrogel in an alkaline coagulation solution for aging, and the aging time is 1 to 5 hours.

[0026] In one or more embodiments, the cleaning is performed multiple times with water after the aging is completed to wash away excess sodium hydroxide liquid and absorb surface moisture.

[0027] In one or more embodiments, the cross-linking polymerization is performed using a cross-linking agent, wherein the cross-linking agent is 2-5% glutaraldehyde, and the cross-linking time is 12-24 hours, preferably 20-24 hours.

[0028] In one or more embodiments, freeze-drying involves freezing the magnetic foamed chitosan hydrogel at -90°C to -70°C for 3 to 6 hours, followed by vacuum evacuation for 12 to 24 hours. The resulting magnetic foamed chitosan hydrogel is flash-frozen at low temperatures to preserve its original morphology. Air-drying, however, can result in the material becoming shrunken, significantly impacting its adsorption performance as an adsorbent.

[0029] In a third aspect, the present invention provides the use of the magnetic foamed freeze-dried modified chitosan material in the adsorption of mine water pollutants.

[0030] The mine water pollutants include metal ions such as iron, manganese and calcium.

[0031] In a fourth aspect, the present invention provides a method for adsorbing pollutants in mine water, comprising: adding the magnetic foamed freeze-dried modified chitosan material as an adsorbent into the mine water.

[0032] When the heavy metal ions in the mine water pollutants are calcium ions and the calcium ion concentration is 200~220 mg / L, the ratio of adsorbent to mine water is (0.1~5g):(150~250mL).

[0033] When the heavy metal ions in the mine water pollutants are manganese ions and the manganese ion concentration is 30~40 mg / L, the ratio of the adsorbent to the mine water is (0.1~3 g):(150~250 mL), preferably (2~3 g):(150~250 mL).

[0034] When the heavy metal ions in the mine water pollutants are iron ions and the iron ion concentration is 35~45 mg / L, the ratio of adsorbent to mine water is (0.1~3 g):(150~250 mL), preferably (0.8~1.5 g):(150~250 mL).

[0035] One or more of the above technical solutions have the following advantages or beneficial effects:

[0036] (1) The present invention provides a magnetic foaming freeze-dried modified chitosan material by combining ferroferric oxide modification, sodium dodecylsulfonate foaming modification and instant freezing modification. The chitosan material has a microsphere porous structure and can exist stably in neutral, alkaline and high-salt mine water solutions. It has a good removal ability for metal ions such as iron ions, manganese and calcium in mine water.

[0037] (2) The magnetic foamed freeze-dried modified chitosan material provided by the present invention introduces ferroferric oxide. The formed ferroferric oxide nanospheres are magnetic and insoluble in solution. In subsequent adsorption tests, they can significantly improve the adsorption effect of iron ions in mine water. If FeCl3·6H2O is introduced, the iron element of the material will exist in the mine water in an ionic state. Ionic iron is one of the characteristic pollutants in mine water. Not only will it fail to achieve adsorption of common heavy metal ions in mine water, but it will also introduce new pollutants, making it unsuitable for the treatment of mine water pollutants. Therefore, the iron source must be specifically selected as ferroferric oxide.

[0038] (3) The present invention provides a method for preparing modified chitosan microspheres suitable for adsorbing mine water pollutants, which has simple process, convenient operation and control, stable quality, high production efficiency and low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0040] Figure 1 The SEM images and energy spectrum of the magnetic foamed freeze-dried modified chitosan material prepared in Example 1 of the present invention; wherein (a) is a 35X magnified appearance morphology image, (b) is a 25X magnified cross-sectional view, and (c) is a 35X magnified energy spectrum image;

[0041] Figure 2The SEM images and energy spectrum of the material prepared in Comparative Example 2 of the present invention are as follows; wherein (a) is a 50X magnified appearance morphology image, (b) is a 50X magnified cross-sectional image, and (c) is an 80X magnified cross-sectional energy spectrum image;

[0042] Figure 3 The morphology of the material prepared in Comparative Example 1 of the present invention; wherein (a) and (c) are surface morphologies of the shell of the air-dried chitosan material at different magnifications, and (b) is the cross-sectional micromorphology;

[0043] Figure 4 The materials prepared in Example 1 and Comparative Examples 1-3 of the present invention are Ca 2+ Adsorption effect diagram;

[0044] Figure 5 The materials prepared in Example 1 and Comparative Examples 1-3 of the present invention are Mn 2+ Adsorption effect diagram;

[0045] Figure 6 The materials prepared in Example 1 and Comparative Examples 1-3 of the present invention are Fe 2+ Adsorption effect diagram. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0047] Generally, iron and manganese ions do not exist in one type of mine water and a replacement reaction will occur. Therefore, two types of mine water with different properties are selected in the embodiment, a high-salt mine water containing iron ions and a high-salt mine water rich in calcium and manganese ions.

[0048] The idea of ​​comparing the adsorption effects in the present invention is to add the same mass of air-dried chitosan (Comparative Example 1) and the new material of the present invention (Example 1) under full adsorption conditions (40 minutes) to calculate the residual amount of metal ions in the mine water, which is more in line with actual engineering conditions.

[0049] Example 1

[0050] 1. Preparation of magnetic foaming freeze-dried modified chitosan material:

[0051] A method for preparing a magnetic foamed freeze-dried modified chitosan material suitable for adsorbing mine water pollutants comprises the following steps:

[0052] (1) Preparation of magnetic foamed chitosan acetic acid solution: Prepare a diluted acetic acid solution with a mass ratio of 2.5%, take 1.75g ​​of 100nm ferrosoferric oxide powder and mix it with 15.75g of chitosan powder, add the diluted acetic acid solution to 500g, and then add 0.15g of sodium dodecyl sulfate powder, and stir in a water bath at 60℃ until it is completely dissolved.

[0053] (2) Prepare sodium hydroxide coagulation solution: Take 40g of sodium hydroxide powder, add ultrapure water to 500g, place the sodium hydroxide solution on a magnetic stirrer and stir until there is no sodium hydroxide solid at the bottom of the beaker, place it at room temperature and then divide it into small beakers and wait for the coagulation process.

[0054] (3) Solidification of magnetic foamed chitosan hydrogel: During the test, magnetic foamed chitosan acetic acid solution was aspirated in small amounts and multiple times. The remaining magnetic foamed chitosan acetic acid solution was placed in a constant temperature water bath and stirred until the next liquid was taken. The syringe that aspirated the magnetic foamed chitosan acetic acid solution was fixed on the triple micro-injection pump, and an 18G dispensing plastic injection needle was placed on the syringe head. The height of the test bench below the micro-injection pump was adjusted until the center of the syringe needle was 10 cm above the liquid level. The syringe was pushed at a speed of 1.32 μL / min, and the solution was dripped into the prepared sodium hydroxide coagulation solution.

[0055] (4) Hydrogel aging: The solidified magnetic foamed chitosan hydrogel was placed in a sodium hydroxide coagulation solution and aged for more than 1 hour to solidify the unsolidified magnetic foamed chitosan. After the aging was completed, it was washed three times with ultrapure water to wash away the excess sodium hydroxide liquid and absorb the surface moisture.

[0056] (5) Cross-linking polymerization of magnetic foamed chitosan: Prepare a 3% glutaraldehyde solution, place the magnetic foamed chitosan hydrogel spheres in the glutaraldehyde cross-linking agent for 20-24 hours, and after the cross-linking is completed, wash them twice with anhydrous ethanol and three times with ultrapure water.

[0057] (6) Preparation of magnetic foamed chitosan aerogel: After drying the surface moisture of the magnetic foamed chitosan hydrogel balls, spread them flat on the freeze dryer tray, place the tray in a cold trap, tighten the air release valve, set the cold trap temperature to -80℃ and freeze for 4 hours, then place the tray in a vacuum chamber. After vacuuming for 18 hours, turn off the vacuum pump, open the air release valve, and take out the freeze-dried magnetic foamed chitosan after the air release is completed. Thaw the freeze-dried magnetic foamed chitosan and let it air dry naturally to remove the remaining moisture.

[0058] 2. Adsorption application of high-salt mine water containing calcium and manganese ions

[0059] (1) Take high-salt mine water containing calcium and manganese ions and put it into a volumetric flask and dilute it to 2L. Shake it evenly and let it stand for 1 hour. Take 800mL of the mine water after standing and divide it evenly into 4 beakers and wait for adsorption test.

[0060] (2) Take 0.5g / 1.5g / 2.5g of the magnetic foamed and freeze-dried modified chitosan materials prepared in step 1 above, respectively, and put them in a gauze bag, soak them in deionized water for 30 minutes, and move the gauze onto a dust-free paper to absorb excess water on the surface.

[0061] (3) Gauze bags containing magnetic foam and freeze-dried modified chitosan were suspended in three beakers of mine water, with the remaining beaker containing mine water serving as a control. Adsorption was performed for 40 min at a simulated underground temperature of 30°C. After adsorption, the gauze bags were removed.

[0062] (4) After the solution was allowed to stand for 20 minutes, the supernatant was aspirated and filtered through a 22-μm organic filter membrane. The residual concentrations of calcium ions and manganese ions in the filtered solution were measured using an inductively coupled plasma emission spectrometer.

[0063] 3. Adsorption application of high-salt mine water containing iron ions

[0064] (1) Take high-salt mine water containing iron ions and put it into a volumetric flask and dilute it to 2L. Shake it evenly and let it stand for 1 hour. Take 1400mL of the mine water after standing and divide it evenly into 7 beakers and wait for adsorption test.

[0065] (2) Take 0.5g / 1.0g / 1.5g / 2.0g / 2.5g of the magnetic foamed and freeze-dried modified chitosan materials prepared in step 1 above, respectively, and put them in a gauze bag, soak them in deionized water for 30 minutes, and move the gauze onto a dust-free paper to absorb excess moisture on the surface.

[0066] (3) Gauze bags containing magnetic foam and freeze-dried modified chitosan were suspended in six beakers of mine water, with the remaining beaker containing mine water serving as a control. Adsorption was performed at a simulated underground temperature of 30°C for 40 minutes, and the gauze bags were removed after adsorption.

[0067] (4) After the solution was allowed to stand for 20 minutes, the supernatant was aspirated and filtered through a 22-μm organic filter membrane. The residual iron ion concentration of the filtered solution was measured using an inductively coupled plasma emission spectrometer.

[0068] Comparative Example 1

[0069] 1. Preparation of air-dried chitosan material:

[0070] (1) Prepare a 2.5% by mass acetic acid dilution solution, take 17.5g of chitosan powder and mix it, add the acetic acid dilution solution to 500g, and stir in a water bath at 60℃ until it is completely dissolved.

[0071] (2) Prepare sodium hydroxide coagulation solution: Take 40g of sodium hydroxide powder, add ultrapure water to 500g, place the sodium hydroxide solution on a magnetic stirrer and stir until the sodium hydroxide solid at the bottom of the beaker is completely dissolved. After leaving it at room temperature, divide it into small beakers and wait for the coagulation process.

[0072] (3) During the test, aspirate chitosan acetic acid solution in small amounts and multiple times. The remaining chitosan acetic acid solution is placed in a constant temperature water bath and stirred until the next time the solution is taken. Fix the syringe that has absorbed the chitosan acetic acid solution on the triple micro-injection pump, cover the 18G dispensing plastic injection needle on the syringe head, adjust the height of the test bench below the micro-injection pump until the center of the syringe needle is 10 cm above the liquid level, and push the syringe at a speed of 1.32 μL / min to drip the solution into the prepared sodium hydroxide coagulation solution.

[0073] (4) Place the solidified chitosan hydrogel in a sodium hydroxide coagulation solution and age it for more than one hour to solidify the unsolidified chitosan. After the aging is complete, wash it three times with ultrapure water to wash away the excess sodium hydroxide solution and absorb the surface moisture.

[0074] (5) Prepare a 3% glutaraldehyde solution and place the chitosan hydrogel spheres in the glutaraldehyde crosslinker for 20-24 hours. After the crosslinking is completed, wash them twice with anhydrous ethanol and three times with ultrapure water.

[0075] (6) After absorbing the moisture on the surface of the chitosan hydrogel balls, place them in a cool and ventilated place and air dry them until they are completely dry before taking them out.

[0076] 2. Adsorption application of high-salt mine water rich in calcium and manganese ions

[0077] (1) Take a high-salt mine water rich in calcium and manganese ions and put it into a volumetric flask and dilute it to 2L. Shake it evenly and let it stand for 1 hour. Take 800mL of the mine water after standing and divide it evenly into 4 beakers and wait for adsorption test.

[0078] (2) Take 0.5g / 1.5g / 2.5g of chitosan material respectively and put it in a gauze bag, soak it in deionized water for 30 minutes, and move the gauze onto dust-free paper to absorb excess water on the surface.

[0079] (3) The chitosan-wrapped gauze bags were suspended in three beakers of mine water, with the remaining beaker containing mine water serving as a control. Adsorption was performed at a simulated underground temperature of 30°C for 40 minutes, and the gauze bags were removed after adsorption.

[0080] (4) After the solution was allowed to stand for 20 minutes, the supernatant was aspirated and filtered through a 22-μm organic filter membrane. The residual concentrations of calcium ions and manganese ions in the filtered solution were measured using an inductively coupled plasma emission spectrometer.

[0081] 3. Adsorption application of high-salt mine water containing iron ions

[0082] (1) Take high-salt mine water containing iron ions and put it into a volumetric flask and dilute it to 2L. Shake it evenly and let it stand for 1 hour. Take 1400mL of the mine water after standing and divide it evenly into 7 beakers and wait for adsorption test.

[0083] (2) Take 0.5g / 1.0g / 1.5g / 2.0g / 2.5g / 3.0g of air-dried chitosan material respectively and put it in a gauze bag, soak it in deionized water for 30 minutes, and move the gauze onto dust-free paper to absorb excess water on the surface.

[0084] (3) Suspend the gauze bags wrapped with air-dried chitosan material in the mine water in six beakers, and use the mine water in the remaining beaker as a control. Adsorption was carried out for 40 minutes at a simulated underground temperature of 30°C. After adsorption, remove the gauze bags.

[0085] (4) After the solution was allowed to stand for 20 minutes, the supernatant was aspirated and filtered through a 22-μm organic filter membrane. The residual iron ion concentration of the filtered solution was measured using an inductively coupled plasma emission spectrometer.

[0086] Comparative Example 2

[0087] The difference from Example 1 is that sodium dodecyl sulfate powder is not added in step (1), and air drying is performed in step (6) instead of freeze drying. The other conditions are the same. Without the addition of sodium dodecyl sulfate, freeze drying is not required because there are no large pores inside.

[0088] Comparative Example 3

[0089] The difference from Example 1 is that step (6) is air-dried instead of freeze-dried, and the other conditions are the same.

[0090] Depend on Figure 1 It can be seen that the magnetic foamed freeze-dried modified chitosan material prepared by the present invention is a porous microsphere structure. Nano-ferroferric oxide particles are evenly distributed on the porous microsphere structure. The particle size of the microspheres is 2-2.5 mm and the pore size is 100-200 μm.

[0091] Without adding sodium dodecyl sulfate powder or without flash freezing, the chitosan spheres will shrink into solid spheres, and the microscopic bubbles and cavities will disappear. Figure 1 (c) and Figure 2The green dots of iron in (c) indicate that without sodium dodecyl sulfate, the iron aggregates and lacks an internal bubble structure. Therefore, the addition of sodium dodecyl sulfate creates a bubble structure that facilitates the dispersion of the iron. Furthermore, after freeze-drying, the bubble structure remains stable for a long time without shrinkage.

[0092] Depend on Figure 4-5 It can be seen that under the same dosage conditions, the magnetic foamed freeze-dried modified chitosan material prepared by the present invention has a higher removal rate of calcium and manganese ions in mine water than air-dried chitosan. When 2.5g is added, the removal rates of the two materials differ by 32% and 35% for calcium and manganese ions, respectively. It can be considered that the magnetic foamed freeze-dried modified chitosan material prepared by the present invention has an approximately 32% and 35% higher adsorption capacity for calcium and manganese in mine water than ordinary air-dried chitosan material.

[0093] Depend on Figure 6 It can be seen that under the same dosage conditions, the magnetic foaming freeze-dried modified chitosan material prepared by the present invention has a higher iron ion removal rate in mine water than air-dried chitosan. When 1g is added, the removal rate difference between the two is about 45%. Therefore, for mine water containing iron ions, the magnetic foaming freeze-dried modified chitosan material prepared by the present invention has an adsorption capacity increased by about 45% compared to conventional air-dried chitosan material.

[0094] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. Application of a magnetic foamed freeze-dried modified chitosan material in the adsorption of mine water pollutants, characterized in that: The magnetic foamed freeze-dried modified chitosan material is a porous microsphere structure, wherein ferrosoferric oxide particles are evenly distributed on the porous microsphere structure; According to weight parts, the magnetic foaming freeze-dried modified chitosan material comprises: 0.1-1 parts of ferrosoferric oxide, 1.2-2 parts of chitosan, and 0.01-0.05 parts of sodium dodecyl sulfate; The method for modifying the magnetic foaming freeze-drying chitosan material comprises the following steps: S1: dissolving ferroferric oxide, chitosan and sodium dodecyl sulfate in an acid solution to prepare a magnetic foaming chitosan acid solution; S2: dripping the magnetic foamed chitosan acid solution into an alkaline coagulation solution to obtain a solidified magnetic foamed chitosan hydrogel, and performing aging, washing, cross-linking polymerization, and freeze-drying to obtain the result; In step S2, the aging is to place the solidified magnetic foamed chitosan hydrogel in an alkaline coagulation solution for aging, and the aging time is 1 to 5 hours; the magnetic foamed freeze-dried modified chitosan material can be stably present in neutral, alkaline and high-salt mine water solutions; The mine water is high-salt mine water, and the mine water pollutants include iron, manganese and calcium metal ions.

2. The use according to claim 1, characterized in that 0.1-0.5 parts of ferrosoferric oxide, 1.4-1.6 parts of chitosan, and 0.01-0.02 parts of sodium lauryl sulfate; The particle size of the microspheres is 2~2.5mm, and the average particle size of the pores is 100~200μm.

3. The use according to claim 1, characterized in that Ferroferric oxide is nano-ferroic oxide powder with a particle size of 100~500nm; The acid is acetic acid, and the mass concentration of the acid solution is 2-3 wt.%; In step S1, according to parts by weight, 0.1-1 parts of ferrosoferric oxide, 1.2-2 parts of chitosan, 0.01-0.05 parts of sodium lauryl sulfate, and 40-60 parts of acid solution; In step S1, the mixture is stirred at 50-70°C until all the components are dissolved.

4. The use according to claim 1, characterized in that In step S2, the alkaline coagulation liquid is a mixture of alkali and water, the alkali is a strong alkali, and the mass ratio of alkali to water is (2-6):(40-60); In step S2, the alkali coagulation liquid is prepared by dissolving alkali in water to obtain an alkali aqueous solution, stirring the solution until no alkali solid is formed, and waiting for coagulation at room temperature.

5. The use according to claim 1, characterized in that In step S2, the dripping method is to use an injection dripping method, specifically: fix the syringe that absorbs the magnetic foamed chitosan acid solution on the triple micro-injection pump, cover the dispensing plastic injection needle on the syringe head, adjust the height of the test bench below the micro-injection pump until the center position of the syringe needle is 5-20 cm above the liquid level, advance the syringe at a propulsion speed of 1-3 μL / min, and drip the solution into the prepared alkaline coagulation solution; In step S2, a small amount of multiple drops are added.

6. The use according to claim 1, characterized in that The cross-linking polymerization is carried out using a cross-linking agent; the cross-linking agent is 2-5% glutaraldehyde, and the cross-linking time is 12-24 hours; The freeze drying process comprises freezing the magnetic foamed chitosan hydrogel at -90 to -70°C for 3 to 6 hours, and then placing the hydrogel in a vacuum for 12 to 24 hours.

Images