A biomass composite aerogel for phosphorus removal and its preparation method

Abstract

This invention provides a biomass composite aerogel for phosphorus removal and its preparation method, belonging to the field of environmental protection technology. The invention employs a composite method to uniformly load UiO-66-NH2 onto a melamine-biomass aerogel. The porous structure of the aerogel provides abundant loading sites for UiO-66-NH2, further enhancing the material's phosphorus adsorption performance. The prepared UiO-66-NH2-loaded melamine-biomass aerogel is a performance-improved biomass aerogel material, capable of rapidly and efficiently removing inorganic phosphates from water bodies, thus addressing the problem of eutrophication.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, specifically relating to a biomass composite aerogel for phosphorus removal and its preparation method. Background Technology

[0002] The rapid development of modern industry inevitably generates large amounts of pollutants such as waste gas and wastewater, severely damaging the environment closely related to human survival and leading to increasingly serious environmental pollution problems. Wastewater pollution not only damages aquatic ecosystems but also affects the safety of drinking water; long-term consumption of contaminated water can lead to health problems. The types of pollutants in wastewater broadly include: solid pollutants, organic pollutants, nutrient pollutants, acid and alkali pollutants, toxic pollutants, oil pollutants, biological pollutants, sensory pollutants, and thermal pollutants. Among these, nutrient pollutants refer to nitrogen-containing and phosphorus-containing compounds, which can cause eutrophication of water bodies. Phosphorus is a reactive element and does not exist in a free state in nature. The form in which phosphorus exists in wastewater depends on the type of wastewater, with the most common forms being phosphates, polyphosphates, and organic phosphorus.

[0003] Existing technologies for treating phosphorus pollution in water bodies include precipitation, biological treatment, membrane separation, and adsorption. Among these, adsorption, which utilizes porous adsorbents, has certain application value and economic viability. Porous adsorbent materials include activated carbon, natural organic adsorbents, natural inorganic adsorbents, and advanced nanomaterials. Advanced nanomaterials have emerged in recent years and have made some progress in research on phosphorus pollution. Aerogels, as an advanced nanomaterial, possess characteristics such as ultra-low density, highly porous structure, large specific surface area, and thermal insulation; however, their application in treating phosphorus pollution still requires further research. Summary of the Invention

[0004] This invention is made to solve the above-mentioned problems, and its purpose is to provide a biomass composite aerogel for phosphorus removal and a method for preparing the same.

[0005] This invention provides a method for preparing a biomass composite aerogel for phosphorus removal, characterized by the following steps: S10, preparing UiO-66-NH2 using a solvothermal method; S20, adding UiO-66-NH2 to a biomass solution and mixing to obtain a suspension; S30, sequentially adding melamine solution, cyanuric acid solution, ammonia water, and silver nitrate solution to the suspension to obtain a hydrogel; S40, drying the hydrogel to obtain a biomass composite aerogel, wherein the biomass composite aerogel is used to remove phosphates from water.

[0006] The preparation method of biomass composite aerogel for phosphorus removal provided by the present invention may also have the following features: wherein step S10 includes the following sub-steps: S11, zirconium tetrachloride and aminoterephthalic acid are uniformly dissolved in a solvent and acetic acid is added thereto to obtain a mixture; S12, the mixture is heated and then cooled to produce a precipitate; S13, the precipitate is washed and dried to obtain UiO-66-NH2.

[0007] The preparation method of biomass composite aerogel for phosphorus removal provided by the present invention may also have the following features: in step S11, the molar ratio of zirconium tetrachloride and aminoterephthalic acid is 1:1; in step S12, the heating method is heating at 120°C for 16 hours in a high-temperature oven, and the cooling method is natural cooling to room temperature; in step S13, the washing method is washing with DMF and anhydrous ethanol, and the drying method is placing it in a vacuum drying oven overnight.

[0008] The preparation method of biomass composite aerogel for phosphorus removal provided by the present invention may also have the following features: wherein, in step S20, the biomass includes chitosan or cellulose, the biomass concentration in the biomass solution is 0.05wt%, and the concentration of UiO-66-NH2 in the suspension is 0.0125wt% to 0.025wt%.

[0009] The preparation method of biomass composite aerogel for phosphorus removal provided by the present invention may also have the following feature: wherein the mass ratio of biomass to UiO-66-NH2 in the suspension is (4~2):1.

[0010] The preparation method of biomass composite aerogel for phosphorus removal provided by the present invention may also have the following characteristics: in step S30, the concentration of melamine in the melamine solution is 20 mmol / L, the concentration of cyanuric acid in the cyanuric acid solution is 20 mmol / L, the concentration of ammonia in the ammonia water is 10 wt%, and the concentration of silver nitrate in the silver nitrate solution is 15 mmol / L to 35 mmol / L.

[0011] The preparation method of biomass composite aerogel for phosphorus removal provided by the present invention may also have the following characteristics: wherein ammonia water is used to adjust the pH value of the hydrogel, and the volume ratio of the suspension, melamine solution, cyanuric acid solution, ammonia water and silver nitrate solution is 1:1:1:0.4:2.

[0012] The preparation method of biomass composite aerogel for phosphorus removal provided by the present invention may also have the following feature: in step S40, the drying method is vacuum freeze drying.

[0013] The present invention also provides a biomass composite aerogel for phosphorus removal, characterized in that it is prepared by any of the preceding methods for preparing biomass composite aerogel for phosphorus removal.

[0014] The role and effect of invention

[0015] According to the present invention, a biomass composite aerogel for phosphorus removal and its preparation method are disclosed. The biomass composite aerogel is prepared by the following steps: S10, preparing UiO-66-NH2 by a solvothermal method; S20, adding UiO-66-NH2 into a biomass solution and mixing to obtain a suspension; S30, sequentially adding melamine solution, cyanuric acid solution, ammonia water and silver nitrate solution to the suspension to obtain a hydrogel; S40, drying the hydrogel to obtain the biomass composite aerogel.

[0016] Therefore, this invention employs a composite method to uniformly load UiO-66-NH2 onto melamine-biomass aerogel. The porous structure of the aerogel provides abundant loading sites for UiO-66-NH2, further enhancing the material's phosphorus adsorption performance. The prepared UiO-66-NH2-loaded melamine-biomass aerogel is a performance-improved material of biomass aerogel, capable of rapidly and efficiently removing inorganic phosphates from water bodies, thus addressing the problem of eutrophication.

[0017] UiO-66-NH2 possesses a large specific surface area and high water stability, adsorbing phosphate in phosphate solutions through electrostatic attraction, hydrogen bonding, and complexation. Chitosan, a product of chitin deacylation, contains abundant functional groups, such as hydroxyl (-OH) and amino (-NH2) groups. Cellulose molecules also contain abundant hydroxyl (-OH) groups, which can react with phosphate ions in phosphate solutions, thus achieving phosphorus removal. Adding silver nitrate to a mixed solution of melamine, cyanuric acid, and ammonia causes two-thirds of the protons in cyanuric acid to be replaced by silver ions and released into the solution. Silver ions alternately form coordination bonds with nitrogen atoms in melamine, cyanuric acid, and chitosan, or oxygen atoms in cellulose, integrating into the framework and achieving successful cross-linking. These cross-links then self-assemble into multilayer hydrogels, which are freeze-dried to obtain aerogels. The aerogels possess specific adsorption sites, thus achieving a certain phosphorus removal effect. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for preparing biomass composite aerogel according to an embodiment of the present invention;

[0019] Figure 2 This is the Fourier Transform Infrared (FTIR) spectrum of sample 1 according to an embodiment of the present invention;

[0020] Figure 3 This is a scanning electron microscope (SEM) image of sample 1 from an embodiment of the present invention at resolutions of 20 μm and 5 μm. Detailed Implementation

[0021] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate a biomass composite aerogel for phosphorus removal and its preparation method.

[0022] <Example>

[0023] Figure 1 This is a flowchart illustrating the preparation method of biomass composite aerogel according to an embodiment of the present invention.

[0024] like Figure 1 As shown, this embodiment provides a method for preparing biomass composite aerogel for phosphorus removal, including the following steps:

[0025] S10, UiO-66-NH2 is prepared by a solvothermal method, specifically including the following sub-steps:

[0026] S11, 0.6 mol zirconium tetrachloride and 0.6 mol aminoterephthalic acid were uniformly mixed in 12.5 mL of DMF and 2.5 mL of acetic acid was added to obtain a mixed solution;

[0027] S12, the mixture is transferred to a glass bottle and heated in a high-temperature oven at 120°C for 16 hours. After naturally cooling to room temperature, a precipitate is formed.

[0028] S13, the precipitate was washed three times with DMF and anhydrous methanol to obtain a yellow solid, which was then dried overnight in a vacuum oven to obtain UiO-66-NH2.

[0029] S20, add UiO-66-NH2 into a 0.05wt% biomass (chitosan or cellulose) solution and stir at a mechanical stirring rate of 500rpm for 30min to obtain a suspension, and make the concentration of UiO-66-NH2 in the suspension 0.0125wt% to 0.025wt%.

[0030] In this step, the mass ratio of biomass to UiO-66-NH2 in the suspension is controlled to be (4~2):1.

[0031] S30: After ultrasonically dispersing the suspension for 30 min, a certain volume is transferred using a pipette and added to a centrifuge tube. Then, 20 mmol / L melamine solution, 20 mmol / L cyanuric acid solution, and 10 wt% ammonia water are added sequentially. After ultrasonication for 10 s, 15 mmol / L to 35 mmol / L silver nitrate solution is added to obtain a hydrogel.

[0032] The volume ratio of the suspension, melamine solution, cyanuric acid solution, ammonia water and silver nitrate solution is 1:1:1:0.4:2.

[0033] S40, after freezing the hydrogel with liquid nitrogen, freeze-dry it under vacuum to obtain UiO-66-NH2-loaded biomass composite aerogel.

[0034] This embodiment also provides a biomass composite aerogel for phosphorus removal, which is prepared by the preparation method of the biomass composite aerogel for phosphorus removal provided in this embodiment. A total of four UiO-66-NH2-loaded biomass composite aerogels were prepared, which are referred to as sample 1, sample 2, sample 3 and sample 4, respectively. The different raw material selection and feeding amount and other operating conditions in the preparation process are shown in Table 1.

[0035] Table 1 (Operating conditions such as different raw material selection and feed amount during the preparation of samples 1-4)

[0036]

[0037] Figure 2 This is the infrared spectrum (FTIR) of sample 1 according to an embodiment of the present invention.

[0038] like Figure 2 As shown, 3323cm -1 The absorption peak at 3125 cm⁻¹ is the -OH stretching vibration peak. -1 The absorption peak at 2799 cm⁻¹ is an associated amino peak, indicating that the prepared UiO-66-NH₂-supported melamine-chitosan aerogel contains amino groups; -1 The vibration is a stretching vibration of -CH2- at 1690 cm. -1 ~1640cm -1 The vibration is a double bond stretching vibration of -C=N at 1524 cm. -1 The point is the stretching vibration of the triazine ring, 1313 cm. -1 The vibration at 780 cm⁻¹ is the stretching vibration of CO, and the vibration at 780 cm⁻¹ is the bending vibration of CH.

[0039] Figure 3 This is a scanning electron microscope (SEM) image of sample 1 from an embodiment of the present invention at resolutions of 20 μm and 5 μm.

[0040] like Figure 3 As shown, the melamine-chitosan aerogel structure supported by UiO-66-NH2 in sample 1 is dense with obvious pores and contains UiO-66-NH2.

[0041] <Test Example>

[0042] This test case examines the phosphorus removal effect of the biomass composite aerogel used for phosphorus removal in the embodiment.

[0043] The test method for the phosphorus removal effect of biomass composite aerogel is as follows:

[0044] The biomass composite aerogel was placed in a centrifuge tube containing 25 mL of phosphate solution for static adsorption for 5 min. A simulated phosphorus adsorption experiment was conducted using this method. After adsorption, the solution was filtered through a filter membrane, and the phosphorus concentration was determined by ion chromatography.

[0045] Among them, the phosphorus adsorption capacity of sample 1 (melamine-chitosan aerogel supported by UiO-66-NH2) was 10.76 mg P / g; the phosphorus adsorption capacity of sample 2 (melamine-chitosan aerogel supported by UiO-66-NH2) was 7.76 mg P / g; the phosphorus adsorption capacity of sample 3 (melamine-chitosan aerogel supported by UiO-66-NH2) was 11.78 mg P / g; and the phosphorus adsorption capacity of sample 4 (melamine-cellulose aerogel supported by UiO-66-NH2) was 1.91 mg P / g.

[0046] The role and effect of the embodiments

[0047] In the examples, excessive loading of UiO-66-NH2 in the biomass composite aerogel would reduce the porosity of the aerogel and decrease the number of effective adsorption sites; conversely, insufficient loading would increase the porosity but reduce the phosphorus removal efficiency. Therefore, there exists an optimal range for UiO-66-NH2 concentration and biomass mass ratio. In this example, the mass concentration of UiO-66-NH2 is 0.0125%–0.025%, and the mass ratio of UiO-66-NH2 to biomass is 1:(2–4). This ensures both a reasonable UiO-66-NH2 loading and a sufficient number of adsorption sites in the aerogel, thereby achieving the best overall phosphorus removal efficiency.

[0048] As demonstrated by the examples and test cases, the biomass composite aerogel for phosphorus removal prepared in this example is an ultralight material capable of efficiently and rapidly absorbing phosphorus from water. The melamine-chitosan aerogel supported on UiO-66-NH2 uses biomass materials as raw materials, thus avoiding secondary pollution to the environment. Chitosan contains abundant hydroxyl (-OH) and amino (-NH2) groups, which can react with phosphate ions in phosphate solutions. Furthermore, the loading of the water-stable, low-toxicity, and low-cost MOF material UiO-66-NH2 within the gel further enhances the material's phosphorus adsorption capacity. SEM results show that UiO-66-NH2 is uniformly loaded within the aerogel, and the aerogel itself possesses a rich porous structure, all of which contribute to the material's efficient adsorption of phosphorus in water.

[0049] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing biomass composite aerogel for phosphorus removal, characterized in that, Includes the following steps: S10, UiO-66-NH2 was prepared by a solvothermal method; S20, UiO-66-NH2 is added to a biomass solution and mixed to obtain a suspension. The biomass includes chitosan or cellulose. The concentration of UiO-66-NH2 in the suspension is 0.0125wt% to 0.025wt%, and the mass ratio of the biomass to UiO-66-NH2 in the suspension is (4~2):

1. S30, melamine solution, cyanuric acid solution, ammonia water and silver nitrate solution are added sequentially to the suspension to obtain hydrogel; S40, dry the hydrogel to obtain a biomass composite aerogel. The biomass composite aerogel is used to remove phosphates from water.

2. The method for preparing biomass composite aerogel for phosphorus removal according to claim 1, characterized in that: in, Step S10 includes the following sub-steps: S11, zirconium tetrachloride and aminoterephthalic acid are uniformly dissolved in a solvent and acetic acid is added to obtain a mixed solution; S12, the mixture is heated and then cooled to produce a precipitate; S13, the precipitate is washed and dried to obtain UiO-66-NH2.

3. The method for preparing biomass composite aerogel for phosphorus removal according to claim 2, characterized in that: in, In step S11, the molar ratio of zirconium tetrachloride to aminoterephthalic acid is 1:

1. In step S12, the heating method is to heat at 120°C in a high-temperature oven for 16 hours, and the cooling method is to allow it to cool naturally to room temperature. In step S13, the washing method is to wash with DMF and anhydrous ethanol, and the drying method is to place it in a vacuum drying oven overnight.

4. The method for preparing biomass composite aerogel for phosphorus removal according to claim 1, characterized in that: in, In step S20, the biomass concentration in the biomass solution is 0.05 wt%.

5. The method for preparing biomass composite aerogel for phosphorus removal according to claim 4, characterized in that: in, In step S30, the concentration of melamine in the melamine solution is 20 mmol / L. The concentration of cyanuric acid in the cyanuric acid solution is 20 mmol / L. The ammonia concentration in the ammonia solution is 10 wt%. The concentration of silver nitrate in the silver nitrate solution is 15 mmol / L to 35 mmol / L.

6. The method for preparing biomass composite aerogel for phosphorus removal according to claim 5, characterized in that: in, The ammonia solution is used to adjust the pH value of the hydrogel. The volume ratio of the suspension, the melamine solution, the cyanuric acid solution, the ammonia water, and the silver nitrate solution is 1:1:1:0.4:

2.

7. The method for preparing biomass composite aerogel for phosphorus removal according to claim 1, characterized in that: in, In step S40, the drying method is vacuum freeze drying.

8. A biomass composite aerogel for phosphorus removal, characterized in that, It is prepared by the method for preparing biomass composite aerogel for phosphorus removal as described in any one of claims 1 to 7.

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