Modified walnut green husk biomass charcoal, preparation method and application thereof in adsorbing nipagin ester

Abstract

The application provides a modified walnut green husk biomass charcoal, a preparation method and application thereof in adsorbing nipagin ester in water bodies. The preparation method of the modified walnut green husk biomass charcoal comprises the following steps: taking walnut green husk powder as raw material, and performing impregnation modification treatment by using a solution containing a modifier to obtain modified walnut green husk powder; the modifier is ZnCl2, NH4Cl, MgCl2 or CaCl2; and the modified walnut green husk powder is subjected to carbonization treatment to obtain the modified walnut green husk biomass charcoal. The prepared modified walnut green husk biomass charcoal can efficiently and quickly adsorb and remove nipagin ester with high selectivity and high sensitivity, and is green, environmentally friendly and pollution-free.

Description

Technical Field

[0001] This invention relates to the fields of resource recycling and pollutant removal, specifically to a modified walnut green husk biochar, its preparation method, and its application in adsorbing parabens in water. Background Technology

[0002] Walnut husks are a major byproduct of walnut processing; they are the outer green outer skin of the walnut and are usually discarded after the walnuts are peeled. According to statistics, China's annual walnut production exceeds 4 million tons, a huge annual output. Walnut husks are rich in phenolic compounds, cellulose, and hemicellulose, but currently most are haphazardly dumped or landfilled, not only occupying land but also easily generating leachate and foul odors, causing environmental pollution. Therefore, how to rationally and efficiently dispose of and utilize this vast resource of walnut husks has become a focus of research in recent years.

[0003] Parabens, a widely used class of persistent pollutants, are continuously introduced into aquatic environments through domestic sewage and are difficult to completely remove even in wastewater treatment systems. Due to their lipophilic nature, they readily distribute in aquatic / sediment systems and are transported along the food chain, leading to bioaccumulation in aquatic organisms. Studies have shown that parabens have potential endocrine-disrupting effects on aquatic organisms, causing neurobehavioral toxicity in fish and leading to impaired reproductive function and altered microbial community structure in aquatic invertebrates. More concerningly, parabens are converted into halogenated products in water bodies through processes such as chlorination. These halogenated products have longer half-lives and are often more ecotoxic than the parent compounds, even exceeding their concentrations in some water bodies, making them a new pollutant requiring close monitoring. Summary of the Invention

[0004] To overcome the problems of ineffective utilization of walnut green husks and environmental pollution caused by parabens in the prior art, this invention provides a modified walnut green husk biochar, its preparation method, and its application in adsorbing parabens in water. The prepared modified walnut green husk biochar can efficiently, rapidly, selectively, and sensitively adsorb and remove parabens, and is green, environmentally friendly, and pollution-free.

[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing modified walnut green husk biochar, comprising the following steps: Walnut green husk powder is used as raw material and is impregnated and modified with a solution containing a modifier to obtain modified walnut green husk powder; the modifier is ZnCl2, NH4Cl, MgCl2 or CaCl2; Modified walnut husk powder was carbonized to obtain modified walnut husk biochar.

[0006] Preferably, the modifier is CaCl2.

[0007] Preferably, the mass ratio of the modifier to the walnut green husk powder is (1~3):1.

[0008] Preferably, the impregnation modification treatment takes 4 to 12 hours.

[0009] Preferably, the carbonization treatment is carried out at a temperature of 500~800℃ for 2~4 hours.

[0010] Secondly, the present invention provides a modified walnut green husk biochar obtained by the preparation method described above.

[0011] Thirdly, the present invention provides an application of the modified walnut green husk biochar in the adsorption and removal of parabens from water.

[0012] Preferably, the structural formula of the paraben is:

[0013] Where R is -CH3, -C2H5, -C3H7 or -C4H9.

[0014] Specifically, the application of modified walnut green husk biochar in the adsorption and removal of parabens in water is as follows: the modified walnut green husk biochar is added to water containing parabens, and adsorption is carried out at normal pressure and 20~80℃ to remove paraben pollutants from the water.

[0015] Furthermore, anhydrous ethanol was used as a desorbent to desorb the saturated modified walnut husk biochar. The desorbed modified walnut husk biochar was washed with water until neutral and then used for the next adsorption.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention relates to modified walnut husk biochar, prepared from walnut husks using an impregnation method followed by carbonization. Modification with a modifier significantly optimizes its pore structure, resulting in biochar with a larger specific surface area and superior adsorption performance. Adsorption experiments demonstrate that the obtained modified walnut husk biochar exhibits high adsorption capacity for parabens in water, making it suitable for the removal and treatment of such pollutants in water. Furthermore, this invention achieves the resource utilization of walnut husk waste. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 SEM image of the modified walnut green husk biochar prepared in Example 1; Figure 2 The graph shows the effect of modified walnut green husk biochar prepared by different modifiers on the adsorption of methylparaben in Example 2. Figure 3 This is a graph showing the effect of different concentrations on the adsorption of methylparaben in Example 3; Figure 4 This is a graph showing the effect of different temperatures on the adsorption of methylparaben in Example 4; Figure 5 This is a graph showing the effect of different time points on the adsorption of methylparaben in Example 5. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand 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, and 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.

[0020] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0021] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0022] The method for preparing modified walnut green husk biochar according to the present invention includes the following steps: Walnut green husk powder is used as raw material and is impregnated and modified with a solution containing a modifier to obtain modified walnut green husk powder; the modifier is ZnCl2, NH4Cl, MgCl2 or CaCl2; Modified walnut husk powder was carbonized to obtain modified walnut husk biochar.

[0023] Compared with ZnCl2, NH4Cl, and MgCl2, modified walnut green husk biochar obtained by CaCl2 modification has a better adsorption effect on paraben pollutants. Therefore, CaCl2 is the preferred modifier.

[0024] In some embodiments of the present invention, the mass ratio of the activator to the walnut green skin powder is (1~3):1, and the impregnation modification treatment time is 4~12 h.

[0025] In some embodiments of the present invention, the carbonization treatment is carried out at a temperature of 500~800℃ for 2~4 h, and the carbonization treatment is carried out under anaerobic conditions (e.g., nitrogen conditions).

[0026] The method of this invention involves grinding and sieving the product after carbonization to obtain modified walnut green skin biomass with a particle size of 1-5 mm and a pH value of 6.5-8.

[0027] The modified walnut green husk biochar prepared by the above preparation method of the present invention has developed a multi-microporous structure, which provides more binding sites for adsorbing parabens.

[0028] Therefore, the modified walnut green husk biochar prepared by this invention can be used for the adsorption treatment of parabens in water, and can efficiently remove parabens from water.

[0029] The steps for using the modified walnut green husk biochar to adsorb and remove paraben pollutants from water are as follows: Modified walnut green husk biochar was added to water bodies containing parabens and adsorbed at normal pressure and 20-80 °C to remove parabens from the water.

[0030] In the above-mentioned methods for adsorbing and removing parabens from water, the adsorption temperature can be 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, etc. When the temperature is below 60 ℃, the adsorption effect of modified walnut husk biochar increases with increasing temperature; when the temperature is above 60 ℃, the adsorption effect of modified walnut husk biochar gradually decreases. Therefore, the optimal adsorption temperature for parabens by modified walnut husk biochar is 60 ℃.

[0031] In the above-mentioned method for adsorbing and removing parabens from water, the adsorption time can be 1 to 8 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours, more preferably 4 hours, after which the adsorption is basically saturated.

[0032] The modified walnut husk biochar can be recycled after adsorbing parabens. Specifically, anhydrous ethanol is used as a desorbent to desorb the saturated modified walnut husk biochar. The desorbed modified walnut husk biochar is then washed with water until neutral and used for the next adsorption.

[0033] The structural formula of the paraben contaminants described in this invention is as follows:

[0034] Where R is -CH3, -C2H5, -C3H7 or -C4H9.

[0035] The results of this invention show that the modified walnut green husk biochar has good adsorption effects on methylparaben, ethylparaben, and propylparaben.

[0036] This invention reveals that the optimal adsorption effect of modified walnut husk biochar is achieved when the modifier is CaCl2, the adsorption temperature is 60℃, and the adsorption time is 4 h. Furthermore, even after five repeated uses, the removal rate of methylparaben by the modified walnut husk biochar remains above 70% of the initial removal rate. Therefore, the adsorption method for parabens using modified walnut husk biochar of this invention offers advantages such as resource recycling, minimal environmental pollution, and good adsorption capacity, making it a convenient and rapid method for removing parabens.

[0037] Example 1: Preparation of modified walnut green husk biochar Take 10 g of walnut green husk powder, wash with deionized water to remove impurities, add 100 mL of 10 mg / L CaCl2 solution, and impregnate at room temperature (25 ℃) for 12 h. After impregnation, filter, and soak the filter cake in concentrated hydrochloric acid (36.5% by mass) for 4 h for acid washing. After acid washing, filter, and repeatedly wash the filter cake with deionized water until the pH of the washing solution is 7, and then dry at 105 ℃ for 12 h to obtain modified walnut green husk powder. Using the modified walnut green husk powder as raw material, heat to 600 ℃ in an oxygen-free environment for pyrolysis treatment for 3 h. After complete carbonization, cool naturally to room temperature under oxygen-free conditions, and collect the solid residue after gas and oil production, which is the modified walnut green husk biochar. After the product is thoroughly mixed and ground, pass through a 0.147 mm standard sieve, and store in a desiccator in a sealed container for later use.

[0038] Scanning electron microscopy (SEM) characterization results Figure 1 The results show that after the modified walnut green skin is pyrolyzed into biochar, the carbon matrix forms a rich multi-level microporous structure under the action of oxidation and etching. This structure can provide sufficient active binding sites for the adsorption of target pollutants.

[0039] Experimental Example 2: Selection of Modifier Following the preparation method of Example 1, the modifier CaCl2 was replaced with ZnCl2, NH4Cl, and MgCl2, respectively, while other conditions remained the same as in Example 1, resulting in different modified walnut husk biochar. Simultaneously, by omitting the modifier CaCl2 and directly subjecting the walnut husk powder to pyrolysis, unmodified walnut husk biochar was prepared.

[0040] At an initial concentration of 50 mg / L and under normal temperature and pressure, the adsorption and removal rates of parabens by the modified and unmodified walnut husk biochar were determined. The results are as follows: Figure 2 As shown.

[0041] Figure 2 The results showed that the modified walnut husk biochar prepared by CaCl2 modification had the best adsorption effect on parabens, and its removal rate was much higher than that of other modified walnut husk biochar and unmodified walnut husk biochar.

[0042] Example 3 Adsorption of modified walnut green husk biochar on methylparaben solutions of different concentrations Different concentrations of methylparaben (20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 100 mg / L) were prepared. 10 mL of each solution was taken, and 0.1 g of CaCl2-modified walnut husk biochar prepared in Example 1 was added. The solutions were shaken at room temperature and pressure for 4 h to detect the adsorption effect. Figure 3 As shown.

[0043] from Figure 3 It can be seen that the modified walnut green husk biochar has a maximum removal rate of 70.2% for methylparaben solution with an initial concentration of 20 mg / L.

[0044] Example 4: Effect of temperature on the adsorption of methylparaben by modified walnut green husk biochar The modified walnut green husk biochar prepared in Example 1 was added to a methylparaben solution with a concentration of 50 mg / L at temperatures of 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃, respectively. The solution was shaken at normal pressure for 4 h, and the adsorption removal rate was observed and measured. The results are as follows: Figure 4 As shown.

[0045] from Figure 4It can be seen that when the temperature is below 60℃, the adsorption effect of modified walnut husk biochar on methylparaben increases with increasing temperature; when the temperature is above 60℃, the adsorption effect of modified walnut husk biochar on methylparaben gradually decreases. Therefore, the optimal adsorption temperature for modified walnut husk biochar on methylparaben is 60℃.

[0046] Example 5: Effect of time on the adsorption of methylparaben by modified walnut green husk biochar The modified walnut green husk biochar prepared in Example 1 was added to a methylparaben solution with a concentration of 50 mg / L. The adsorption temperature was 60℃, and the adsorption times were set at 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, and 8 h to observe and measure the adsorption removal rate. Figure 5 ).

[0047] from Figure 5 It can be seen that the optimal adsorption time for methylparaben by modified walnut green husk biochar is 4 h, after which the adsorption is basically saturated.

[0048] Experimental Example 6: Optimal Adsorption Process Effect 0.1 g of the modified walnut green skin biochar prepared in Example 1 was added to a methylparaben solution with an initial concentration of 20 mg / L. The adsorption temperature was 60℃ and the adsorption time was 4 h. The maximum removal rate was found to be 79.5%.

[0049] Experimental Example 7: Reuse of Modified Walnut Green Peel Biochar To evaluate the reusability of modified walnut husk biochar, an adsorption-desorption cycle experiment was conducted in this embodiment. Modified walnut husk biochar from Example 6, after adsorption saturation, was centrifuged and desorbed using anhydrous ethanol as the desorbent. The mixture was shaken and desorbed at room temperature for 2 hours, then washed with deionized water until neutral, dried, and reused in the next round of adsorption experiments. This process was repeated 5 times, and the removal rate was recorded for each cycle. The reusability test results are shown in Table 1. In the first cycle, the removal rate of methylparaben by the modified walnut husk biochar was 75.4%; in the second cycle, it was 73.2%; in the third cycle, it was 70.4%; in the fourth cycle, it was 65.3%; and in the fifth cycle, it was 62.1%.

[0050] Table 1. Removal rate of methylparaben from reused biochar

[0051] Experimental results show that after five adsorption-desorption cycles, the modified walnut green husk biochar can still maintain more than 70% of the initial removal rate of methylparaben, indicating that the biochar has good reusability and regeneration capacity, and has high economic efficiency and practicality in actual water treatment applications.

[0052] Experimental Example 8: Adsorption Effect of Modified Walnut Green Peel Biochar on Different Types of Parabens To verify the adsorption effect of modified walnut green husk biochar on different types of parabens, this example conducted adsorption experiments with ethylparaben and propylparaben as target pollutants.

[0053] Accurately weigh 0.1 g of the modified walnut husk biochar prepared in Example 1, and add it to ethylparaben and propylparaben solutions with an initial concentration of 20 mg / L, respectively. Adjust the pH to neutral, and adsorb in a constant temperature shaker at 60℃ for 4 h. After adsorption, filter through a 0.45 μm filter membrane and calculate the removal rate. The results show that the modified walnut husk biochar has a removal rate of 75.8% for ethylparaben and 77.6% for propylparaben; this indicates that the CaCl2-modified walnut husk biochar also has excellent adsorption performance for both ethylparaben and propylparaben.

[0054] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing modified walnut green husk biochar, characterized in that, Includes the following steps: Walnut green husk powder is used as raw material and is impregnated and modified with a solution containing a modifier to obtain modified walnut green husk powder; the modifier is ZnCl2, NH4Cl, MgCl2 or CaCl2; Modified walnut husk powder was carbonized to obtain modified walnut husk biochar.

2. The method for preparing modified walnut green husk biochar according to claim 1, characterized in that, The modifier is CaCl2.

3. The method for preparing modified walnut green husk biochar according to claim 1, characterized in that, The mass ratio of the modifier to the walnut green skin powder is (1~3):

1.

4. The method for preparing modified walnut green husk biochar according to claim 1, characterized in that, The impregnation modification treatment takes 4 to 12 hours.

5. The method for preparing modified walnut green husk biochar according to claim 1, characterized in that, The carbonization process is carried out at a temperature of 500-800℃ for 2-4 hours.

6. Modified walnut green husk biochar obtained by the preparation method according to any one of claims 1 to 5.

7. The application of the modified walnut green husk biochar according to claim 6 in the adsorption and removal of parabens from water.

8. The application according to claim 7, characterized in that, The structural formula of the paraben is: Where R is -CH3, -C2H5, -C3H7 or -C4H9.

9. The application according to claim 7, characterized in that, Modified walnut green husk biochar was added to water containing parabens and adsorbed at normal pressure and 20-80℃ to remove paraben pollutants from the water.

10. The application according to claim 9, characterized in that, Anhydrous ethanol was used as the desorbent to desorb the saturated modified walnut green husk biochar. The desorbed modified walnut green husk biochar was washed with water until neutral and then used for the next adsorption.

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