A method for preparing a heavy metal adsorbent from walnut green husk waste.

Abstract

This invention relates to a method for preparing a heavy metal adsorbent from walnut green husk waste. In the La-PPY-walnut green husk powder composite adsorbent of this invention, each component not only independently adsorbs heavy metal ions but also exhibits a synergistic effect through interaction. For example, the introduction of lanthanum ions not only provides specific adsorption sites but also enhances the electronic interactions during polypyrrole formation, thereby improving the overall adsorption capacity. Simultaneously, the introduction of aluminum ions and phosphoric acid modification can interact with the lanthanum-polypyrrole composite system to form a multifunctional adsorption platform capable of effectively adsorbing and immobilizing heavy metal ions in both physical and chemical ways.

Description

Technical Field

[0001] This invention relates to the field of heavy metal adsorbent technology, specifically to a method for preparing a heavy metal adsorbent from walnut green husk waste. Background Technology

[0002] Heavy metals, such as lead, mercury, cadmium, and chromium, are mainly released into the environment through industrial wastewater discharge, mining, and the use of agricultural fertilizers and pesticides. These pollutants are highly stable in water bodies and do not readily degrade through natural biological processes, allowing them to accumulate in aquatic environments over long periods. Over time, these heavy metals gradually accumulate through the food chain and ultimately affect human health.

[0003] In addressing heavy metal pollution in water, various treatment methods have been developed and applied. These methods include chemical precipitation, ion exchange, reverse osmosis, and adsorption technologies. Adsorption technology is widely used for removing heavy metals from water due to its advantages of simple operation, relatively low cost, and high treatment efficiency. Among many adsorbent materials, walnut shells exhibit good adsorption performance due to their rich cellulose and lignin content. However, current walnut shell-based adsorbents still have some shortcomings in practical applications, such as the need to improve adsorption efficiency, limited adsorption capacity for specific heavy metal ions, and challenges in adsorbent regeneration and recycling. These limitations indicate the need to improve existing adsorbent materials or develop new adsorbents to more effectively treat heavy metal pollution in water. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this invention application provides a method for preparing a heavy metal adsorbent from walnut green husk waste.

[0005] The first aspect of this invention provides a method for preparing a heavy metal adsorbent from walnut green husk waste, comprising the following steps:

[0006] S1. After drying the green husks of walnuts, crush them, pass them through an 80-100 mesh sieve, and soak them in 5% phosphoric acid for 24 hours to activate them.

[0007] S2. Add the walnut green skin powder obtained in S1 to lanthanum nitrate solution and stir at room temperature for 10-12 hours. Then add pyrrole and stir at room temperature for 20-40 minutes to obtain solution A. Then dissolve AlCl3·6H2O in deionized water to obtain solution B.

[0008] S3. Add solution B to solution A, stir and react at room temperature for 8-12 hours, then rinse the adsorbent material until the washing solution is colorless, and dry the resulting material.

[0009] Furthermore, the amount of walnut green skin powder used in S2 is 5g.

[0010] Furthermore, the lanthanum nitrate solution described in S2 is in the form of 100 ml, 0.05 mol / L.

[0011] Furthermore, the stirring speed is 180 r / min.

[0012] Furthermore, the pyrrole mentioned in S2 is 1.5 mL.

[0013] Furthermore, the Alcl3·6H2O mentioned in S2 is 10g.

[0014] Furthermore, the drying conditions described in S3 are 60°C for 24 hours.

[0015] The second aspect of this invention provides a heavy metal adsorbent prepared from walnut green husk waste, wherein the phosphorus removal adsorbent is prepared according to the above-described preparation method.

[0016] Furthermore, the adsorbent is a La-PPY-walnut green husk powder composite material.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of this application.

[0018] Beneficial technical effects of the present invention:

[0019] In the La-PPY-walnut husk powder composite adsorbent of the present invention, each component not only independently adsorbs heavy metal ions, but also generates a synergistic effect through interaction. For example, the introduction of lanthanum ions not only provides specific adsorption sites, but also enhances the electronic interactions during the formation of polypyrrole, thereby improving the overall adsorption capacity. Simultaneously, the introduction of aluminum ions and phosphoric acid modification can interact with the lanthanum-polypyrrole composite system to form a multifunctional adsorption platform that can effectively adsorb and immobilize heavy metal ions in a physical and chemical manner. Attached Figure Description

[0020] Figure 1 This is an electron microscope image of the walnut peel before modification in this invention application;

[0021] Figure 2 This is an electron microscope image of the modified green walnut skin in this invention application; Detailed Implementation

[0022] The alternative embodiments of this application will now be described in more detail with reference to the accompanying drawings. While alternative embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0023] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0024] The following is a detailed description of the preparation method of heavy metal adsorbent from walnut green husk waste in this invention application, as follows:

[0025] The method for preparing heavy metal adsorbent from walnut green husk waste in this invention application includes:

[0026] S1. After drying the green husks of walnuts, crush them, pass them through an 80-100 mesh sieve, and soak them in 5% phosphoric acid for 24 hours to activate them.

[0027] Walnut husks are significantly superior to walnut shells as adsorbent substrates, primarily due to their higher functional group content, better biodegradability, and stronger potential for chemical modification. They contain abundant hydroxyl, carboxyl, and phenolic hydroxyl groups, which effectively enhance the adsorption capacity for heavy metal ions. Simultaneously, their excellent biodegradability helps reduce long-term environmental impact. Furthermore, the natural chemical composition of walnut husks offers broader possibilities for chemical modification, such as enhancing adsorption performance through phosphoric acid treatment, making them particularly valuable in the field of adsorbent materials.

[0028] The green husk of walnuts provides a natural polymer matrix, including components such as cellulose, hemicellulose, and lignin, which possess inherent porous structures and functional groups. Modification with phosphoric acid increases the porosity of the material through processes such as acid hydrolysis, while simultaneously introducing additional phosphate functional groups. These functional groups can interact with heavy metal ions such as Pb. 2+ and Cd 2+ Stable phosphate complexes are formed. In addition, the increased porosity increases the surface area for physical adsorption, thereby exerting a synergistic effect between walnut green skin and phosphate modification.

[0029] S2. Add the walnut green skin powder obtained in S1 to lanthanum nitrate solution and stir at room temperature for 10-12 hours. Then add pyrrole and stir at room temperature for 20-40 minutes to obtain solution A. Then dissolve AlCl3·6H2O in deionized water to obtain solution B.

[0030] The specific electron configuration and size introduced by lanthanum enable it to form specific complex adsorption sites with heavy metal ions, especially for heavy metal ions with large ionic radii (such as Pb). 2+ and Cd 2+ The adsorption of ) is facilitated. Simultaneously, the synthesis of polypyrrole (PPY) provides a large number of nitrogen-containing functional groups on the material surface. These functional groups form strong coordination bonds with heavy metal ions, especially for nitrogen-loving heavy metal ions (such as Cr). 3+ / Cr 6+ The introduction of lanthanum ions also promotes the uniform deposition and distribution of polypyrrole, thereby enhancing the complexing effect between lanthanum ions and polypyrrole.

[0031] S3. Add solution B to solution A, stir and react at room temperature for 8-12 hours, then rinse the adsorbent material until the washing solution is colorless, and dry the resulting material.

[0032] The addition of aluminum ions further enhances the chemical stability and adsorption performance of the adsorbent. Aluminum salts provide new adsorption sites on the material surface by forming oxide or hydrate layers, and synergistically with the functional groups of walnut husk and polypyrrole to enhance the adsorption of specific heavy metal ions (such as Cr). 3+ / Cr 6+ The presence of this aluminum layer not only improves the physical properties of the adsorbent, such as hardness and corrosion resistance, but also promotes the processes of chemical adsorption and ion exchange.

[0033] In one embodiment of the present invention, the amount of walnut green skin powder used in S2 is 5g.

[0034] In one embodiment of the present invention, the lanthanum nitrate solution in S2 has a specification of 100 ml and a concentration of 0.05 mol / L.

[0035] In one embodiment of the present invention, the stirring speed is 180 r / min.

[0036] In one embodiment of the present invention, the pyrrole in S2 is 1.5 mL.

[0037] In one embodiment of the present invention, the Alcl3·6H2O in S2 is 10g.

[0038] In one embodiment of the present invention, the drying conditions described in S3 are 60°C for 24 hours.

[0039] In one embodiment of the present invention, the adsorbent prepared according to the above preparation method is a La-PPY-walnut green husk powder composite material.

[0040] For clarity, the following examples will be used to provide a detailed description.

[0041] Example 1

[0042] S1. Dry the green husks of walnuts, crush them, pass them through an 80-mesh sieve, and soak them in 5% phosphoric acid for 24 hours to activate them.

[0043] S2. Add 5g of walnut green skin powder obtained in S1 to 100ml of 0.05mol / L lanthanum nitrate solution, stir and react at room temperature for 10h, then add 1.5mL of pyrrole, stir and react at room temperature for 20min at 180r / min to obtain solution A. Then dissolve 10g of AlCl3·6H2O in deionized water to obtain solution B.

[0044] S3. Add solution B to solution A, stir and react for 8 hours at room temperature, then rinse the adsorbent material until the washing solution is colorless, and dry the resulting material at 60℃ for 24 hours.

[0045] Example 2

[0046] S1. Dry the green walnut skin, crush it, pass it through a 90-mesh sieve, and soak it in 5% phosphoric acid for 24 hours to activate it.

[0047] S2. Add 5g of walnut green skin powder obtained in S1 to 100ml of 0.05mol / L lanthanum nitrate solution, stir and react at room temperature for 11h, then add 1.5mL of pyrrole, stir and react at room temperature for 30min at 180r / min to obtain solution A, then dissolve 10g of AlCl3·6H2O in deionized water to obtain solution B.

[0048] S3. Add solution B to solution A, stir and react for 10 hours at room temperature, then rinse the adsorbent material until the washing solution is colorless, and dry the resulting material at 60℃ for 24 hours.

[0049] Example 3

[0050] S1. After drying the green walnut skin, crush it, pass it through a 100-mesh sieve, and soak it in 5% phosphoric acid for 24 hours to activate it.

[0051] S2. Add 5g of walnut green skin powder obtained in S1 to 100ml of 0.05mol / L lanthanum nitrate solution, stir and react at room temperature for 12h, then add 1.5mL of pyrrole, stir and react at room temperature for 40min at 180r / min to obtain solution A. Then dissolve 10g of AlCl3·6H2O in deionized water to obtain solution B.

[0052] S3. Add solution B to solution A, stir and react for 12 hours at room temperature, then rinse the adsorbent material until the washing solution is colorless, and dry the resulting material at 60℃ for 24 hours.

[0053] Experimental Example 1

[0054] Experimental objective:

[0055] To evaluate the efficacy of walnut shells, walnut husks, and modified walnut husks in removing specific heavy metals from water. Experimental reagents and dosages:

[0056] Walnut shells: Crush and sieve through a 100-mesh sieve.

[0057] Walnut green husk: processed the same as walnut shell.

[0058] Modified walnut husk: prepared according to the method in Example 3

[0059] heavy metal solution

[0060] Experimental methods:

[0061] 1. Sample preparation:

[0062] The walnut shells and green walnut skins were crushed and sieved to a particle size of 0.5 mm.

[0063] 2. Solution preparation:

[0064] Preparation of lead (Pb) solution: concentration 50 mg / L

[0065] Mercury (Hg) solution: concentration 10 mg / L

[0066] Cadmium (Cd) solution: concentration 50 mg / L

[0067] Chromium (Cr) solution: concentration 50 mg / L

[0068] 3. Adsorption experiment:

[0069] Add 4g of adsorbent (walnut shell, walnut green skin, and modified walnut green skin) to beakers containing 100mL of heavy metal solution for each group.

[0070] Stir at 150 rpm in a constant temperature water bath for 2 hours.

[0071] The pH of the solution was maintained at around 3.5 during the experiment.

[0072] 4. Data recording and analysis:

[0073] The adsorbent and solution are separated using a centrifuge.

[0074] The concentration of heavy metal elements in the solution was determined using atomic absorption spectrometry.

[0075] Calculate the adsorption capacity and removal rate.

[0076] Adsorption data of cadmium (Cd) solution (unit: mg / g)

[0077]

[0078] Adsorption data of lead (Pb) solution (unit: mg / g)

[0079]

[0080] Adsorption data of mercury (Hg) solution (unit: mg / g)

[0081]

[0082] Adsorption data of chromium (Cr) solution (unit: mg / g)

[0083]

[0084] The various embodiments of this invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a heavy metal adsorbent from walnut green husk waste, characterized in that, The preparation method includes: S1. Dry the green husks of walnuts, crush them, pass them through an 80-100 mesh sieve, and soak them in 5% phosphoric acid for 24 hours to activate them. S2. Add the walnut green skin powder obtained in S1 to lanthanum nitrate solution and stir at room temperature for 10-12 hours. Then add pyrrole and stir at room temperature for 20-40 minutes to obtain solution A. Then dissolve AlCl3·6H2O in deionized water to obtain solution B. S3. Add solution B to solution A, stir and react for 8-12 hours at room temperature, then rinse the adsorbent material until the washing solution is colorless, and dry the resulting material.

2. The preparation method according to claim 1, characterized in that, The amount of walnut green skin powder mentioned in S2 is 5g.

3. The preparation method according to claim 1, characterized in that, The lanthanum nitrate solution described in S2 is in the form of 100 mL, 0.05 mol / L.

4. The preparation method according to claim 1, characterized in that, The stirring speed for the reactions described in S2 and S3 is 180 r / min.

5. The preparation method according to claim 1, characterized in that, The amount of pyrrole mentioned in S2 is 1.5 mL.

6. The preparation method according to claim 1, characterized in that, The AlCl3·6H2O mentioned in S2 is 10g.

7. The preparation method according to claim 1, characterized in that, The drying conditions described in S3 are 60°C for 24 hours.

8. A method for preparing a heavy metal adsorbent from walnut green husk waste, characterized in that, The adsorbent is prepared according to any one of claims 1 to 7, wherein the adsorbent is a La-PPY-walnut green husk powder composite material.

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