Preparation method of nitrided attapulgite / cellulose composite aerogel
By preparing nitrogenated attapulgite/cellulose composite aerogel as a microbial carrier, the problems of low efficiency and high cost in ammonia nitrogen wastewater treatment were solved, and efficient and economical ammonia nitrogen degradation effect was achieved, which is suitable for industrial application.
Patent Information
- Application Number
- CN202511088606.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2025-09-12
AI Technical Summary
Existing ammonia nitrogen wastewater treatment technologies are inefficient and costly, microorganisms are easily inhibited, and there is a lack of efficient, economical and environmentally friendly treatment materials and methods.
Nitrided attapulgite/cellulose composite aerogel was prepared and treated with acidification, freeze drying and nitridation to form a stable composite structure, which was used as a microbial carrier to improve the adsorption performance and microbial degradation efficiency.
It significantly improves the degradation efficiency of ammonia nitrogen by microorganisms and reduces the ammonia nitrogen content in water bodies. It conforms to the concepts of green chemistry and sustainable development and is suitable for large-scale industrial applications.
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Figure CN120623564A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of environmental materials, and in particular to a method for preparing a nitrided attapulgite / cellulose composite aerogel. Background Art
[0002] With the rapid development of industry and agriculture, the discharge of large amounts of wastewater has led to increasingly serious ammonia nitrogen pollution in the aquatic environment. Ammonia nitrogen exists primarily in the form of ammonium ions in water bodies. Excessive ammonia nitrogen can cause eutrophication, leading to excessive algal growth and the formation of toxic algal blooms, which harm aquatic life. It can also deteriorate drinking water quality and pose a threat to human health. For example, ammonia nitrogen can be converted into nitrates and nitrites, causing diseases such as methemoglobinemia. Furthermore, ammonia gas, produced by the volatilization of ammonia nitrogen, contributes to air pollution, reacting with other pollutants to form fine particulate matter (PM2.5), further deteriorating environmental quality.
[0003] Currently, numerous methods exist for treating ammonia nitrogen in wastewater, including ion exchange, adsorption, biotechnology, air stripping, breakpoint chlorination, chemical precipitation, reverse osmosis, microwave radiation, and supercritical water oxidation. However, these traditional methods have numerous limitations. For example, ion exchange and adsorption methods require regeneration after adsorbent saturation, resulting in high costs. While biotechnology offers advantages such as safety, non-toxicity, and pollution-free performance, high concentrations of chemicals in wastewater can inhibit microbial growth and metabolism, reducing degradation efficiency. Other physical and chemical methods often suffer from high energy consumption, secondary pollution, or complex equipment.
[0004] Biocarriers not only provide stable anchoring sites for microorganisms, isolating them from the toxic or concentration-inhibiting effects of pollutants, but also enrich pollutants through adsorption mechanisms, thereby enhancing mass transfer efficiency and creating a favorable microenvironment for microbial degradation. Cellulose aerogels, with their large surface area and high porosity, are potentially excellent carriers for microorganisms. Attapulgite, due to its unique pore structure, good adsorption properties, and low cost, is widely used in adsorbents, catalyst carriers, and other fields. However, relatively little research has been conducted on the synergistic construction of microbial carriers using these two materials. The existing technology lacks a highly efficient, economical, and environmentally friendly material and method for treating ammonia nitrogen wastewater. Summary of the Invention
[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid blurring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.
[0006] Therefore, the purpose of the present invention is to provide a method for preparing a nitrided attapulgite / cellulose composite aerogel, which is applied in wastewater treatment to solve the problems of low efficiency, high cost, and susceptibility to microbial inhibition in existing ammonia nitrogen wastewater treatment technologies, improve the efficiency of microbial degradation of ammonia nitrogen, and achieve economical and efficient wastewater treatment.
[0007] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions: A method for preparing a nitrided attapulgite / cellulose composite aerogel comprises the following steps: S1. Add the attapulgite into concentrated hydrochloric acid, stir and disperse, heat in a water bath and let stand, then filter, wash until neutral, and vacuum dry to obtain an acidified attapulgite; S2, adding the acidified attapulgite to a cellulose nanofiber aqueous solution containing a nitrogen source according to a mass ratio, stirring and ultrasonically treating the mixture, and then freezing the mixed solution and freeze-drying it to obtain an attapulgite / cellulose composite aerogel; S3. Placing the attapulgite / cellulose composite aerogel in a tubular furnace and calcining the attapulgite / cellulose composite aerogel under nitrogen protection to obtain a nitrided attapulgite / cellulose composite aerogel.
[0008] As a preferred embodiment of the method for preparing a nitrided attapulgite / cellulose composite aerogel according to the present invention, in step S1, the mass volume ratio of the attapulgite to concentrated hydrochloric acid is 1 g:30 mL-100 g:30 mL, and the concentration of the concentrated hydrochloric acid is 36.5%.
[0009] As a preferred embodiment of the method for preparing a nitrided attapulgite / cellulose composite aerogel according to the present invention, in step S1, the water bath heating time is 6 hours, the standing time is 24 hours, and the vacuum drying temperature is 60°C.
[0010] As a preferred embodiment of the method for preparing a nitrided attapulgite / cellulose composite aerogel described in the present invention, in step S2, the mass ratio of the acidified attapulgite to the cellulose nanofiber is 1:1-4:1, the concentrations of the nitrogen source and the cellulose nanofiber aqueous solution are 1-100 mg / mL, respectively, the ultrasonic treatment time is 10-30 min, the freeze-drying conditions are -80 to -60°C, and the freeze-drying time is 48 h.
[0011] As a preferred embodiment of the method for preparing the nitrided attapulgite / cellulose composite aerogel according to the present invention, the nitrogen source is one or more of urea, cyanuric acid, and melamine.
[0012] As a preferred embodiment of the method for preparing a nitrided attapulgite / cellulose composite aerogel according to the present invention, in step S3, the heating rate is 5°C / min, the calcination temperature is 150-800°C, and the holding time is 1-4h.
[0013] As a preferred embodiment of the method for preparing a nitrided attapulgite / cellulose composite aerogel described in the present invention, the cellulose in the nitrided attapulgite / cellulose composite aerogel constitutes the aerogel skeleton, the attapulgite is dispersed in the cellulose skeleton, and when the concentration of the CNF aqueous solution is 1-100 mg / mL and the mass ratio of the acidified attapulgite to the cellulose nanofiber is 1:1-4:1, it has a cellulose microtubule structure.
[0014] As a preferred embodiment of the method for preparing the nitrided attapulgite / cellulose composite aerogel described in the present invention, the prepared nitrided attapulgite / cellulose composite aerogel is used as a microbial carrier in wastewater treatment.
[0015] As a preferred embodiment of the method for preparing the nitrided attapulgite / cellulose composite aerogel described in the present invention, the microorganism is Bacillus cabrialesii bacteria, which is used to improve the bacteria's ability to degrade ammonia nitrogen.
[0016] Compared with the prior art, the present invention has the following beneficial effects: The nitrided attapulgite / cellulose composite aerogel prepared by the present invention has a cellulose backbone that provides stable support for the attapulgite, enabling its uniform dispersion and preventing its aggregation, thereby fully utilizing the adsorption properties of the attapulgite. Furthermore, this composite structure provides abundant attachment sites and growth space for microorganisms, facilitating their fixation and growth, thereby improving the efficiency of ammonia nitrogen degradation.
[0017] 2. By acidifying and modifying the attapulgite, compounding it with cellulose to form an aerogel, and nitrogenating it, the pore structure of the attapulgite and cellulose microtubules can be further improved, the specific surface area can be increased, and the active sites can be increased, so that it can more effectively adsorb pollutants such as ammonia nitrogen, providing more favorable conditions for microbial degradation.
[0018] 3. The composite aerogels of the present invention, when used as microbial carriers in wastewater treatment, can significantly improve the efficiency of microbial degradation of ammonia nitrogen. Experimental results show that compared with the control group without composite aerogels, the addition of composite aerogels significantly improved the degradation performance of Bacillus cabrialesii bacteria on ammonia nitrogen, effectively reducing the ammonia nitrogen content in water bodies, providing a highly effective solution to the problem of ammonia nitrogen pollution.
[0019] 4. The raw materials attapulgite and cellulose used in the preparation method of the present invention are widely available and low in cost, and the preparation process is simple and does not produce harmful by-products. It conforms to the concepts of green chemistry and sustainable development, has good economic and environmental benefits, and is suitable for large-scale industrial production and practical applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort. Among them: Figure 1 SEM images of aATP / cellulose composite aerogels prepared in Example 2 of the present invention at CNF aqueous solution concentrations of 1 mg / mL, 2 mg / mL, 4 mg / mL, and 8 mg / mL, respectively; Figure 2 SEM images of aATP / cellulose composite aerogels prepared in Example 2 of the present invention at CNF aqueous solution concentrations of 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, and 0.8 mg / mL, respectively; Figure 3 SEM images of aATP / cellulose composite aerogel materials prepared in Example 3 of the present invention with aATP to CNF mass ratios of 1:2, 1:1, 2:1 and 3:1, respectively. DETAILED DESCRIPTION
[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0022] The present invention provides a preparation method of nitrided attapulgite / cellulose composite aerogel, which is applied in wastewater treatment to solve the problems of low efficiency, high cost, and susceptibility of microorganisms to inhibition in existing ammonia nitrogen wastewater treatment technologies, thereby improving the efficiency of microbial degradation of ammonia nitrogen and achieving economical and efficient wastewater treatment.
[0023] The preparation method of the nitrided attapulgite / cellulose composite aerogel and the prepared nitrided attapulgite / cellulose composite aerogel are described in detail below in conjunction with Examples 1-4. Example
[0024] A method for preparing a nitrided attapulgite / cellulose composite aerogel comprises the following steps: S1: Add 10 g of attapulgite (ATP) to 30 mL of 36.5% concentrated hydrochloric acid and stir thoroughly to disperse evenly. Heat the suspension in a water bath for 6 hours and then let it stand for 24 hours. After acidification, filter the acidified attapulgite (aATP) and repeatedly rinse with deionized water until the pH of the supernatant reaches 7, indicating neutral attapulgite. Finally, vacuum dry the aATP at 60°C and store under vacuum.
[0025] S2: Composite aerogel preparation: aATP was added to a 1 mg / mL aqueous solution of cellulose nanofibers (CNFs) containing urea, at a mass ratio of 2:1. The solution was stirred and sonicated for 10 minutes using an ultrasonic cell grinder to fully disperse the aATP in the CNF solution. The mixed solution was then rapidly cooled in liquid nitrogen to form ice. The frozen solution was then transferred to a freeze dryer and freeze-dried at -80°C and 35 Pa for 48 hours to obtain aATP / cellulose.
[0026] S3: The obtained attapulgite / cellulose composite aerogel (aATP / cellulose) was placed in a tubular furnace. Under nitrogen protection, the temperature was raised to 300°C at a heating rate of 5°C / min. After calcination for 2 hours, it was naturally cooled to room temperature to obtain (nitrided attapulgite / cellulose composite aerogel) N-aATP / cellulose. Example
[0027] To investigate the effect of CNF aqueous solution concentration on the microstructure of aATP / cellulose composite aerogels, multiple experiments were conducted. The experimental procedures were identical to those for preparing aATP / cellulose composite aerogels in Example 1, except that the CNF aqueous solution concentrations were set at 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.8 mg / mL, 1 mg / mL, 2 mg / mL, 4 mg / mL, and 8 mg / mL, respectively.
[0028] The prepared different composite aerogels were characterized by SEM. The morphologies of the four groups of aATP / cellulose composite aerogels at 1 mg / mL, 2 mg / mL, 4 mg / mL, and 8 mg / mL are shown in Figure 2. Figure 1 The SEM morphologies of the four groups of aATP / cellulose composite aerogels at 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, and 0.8 mg / mL are shown in Figure 2. Figure 2The results show that at a CNF aqueous solution concentration of 1 mg / mL, the aATP / 1cellulose composite aerogel exhibits a two-dimensional tubular structure, but its structural integrity and dimensional uniformity need to be improved. At lower concentrations (e.g., 0.1 mg / mL-0.8 mg / mL), the cellulose in the composite aerogel forms an incomplete hollow sphere structure. As the concentration decreases, the spherical structure increases and the tubular structure decreases. At higher concentrations (e.g., 2 mg / mL-8 mg / mL), the tubular structure is gradually replaced by a thick cellulose sheet structure, and the sheet layer continues to grow larger and thicker. Example
[0029] To investigate the effect of the mass ratio of aATP to CNF on the microstructure of aATP / cellulose composite aerogels, multiple experiments were conducted. The experimental process was the same as the preparation steps of aATP / cellulose composite aerogels in Example 1, except that the mass ratios of aATP to CNF were set to 1:2, 1:1, 2:1, and 3:1, respectively. The prepared composite aerogels were characterized by SEM. The morphologies of the four groups of aATP / cellulose composite aerogels are shown in Figure 2. Figure 3 The results show that aATP / cellulose-1:1 has the most excellent cellulose tube structure; when the aATP mass ratio is lower than the optimal mass ratio (50%), a curved sheet structure appears, such as in the aATP / cellulose-1:2 structure; when the aATP mass ratio is higher than the optimal mass ratio, a "hole-like" cellulose sheet structure appears, such as in the aATP / cellulose-2:1 and aATP / cellulose-3:1 composite aerogels. Example
[0030] Performance test of the attapulgite / cellulose composite aerogel prepared by the present invention as a microbial carrier: S1: Prepare nitrogen-deficient culture medium by adding 7.9 g K₂HPO₄·3H₂O, 1.5 g KH₂PO₄, 5 g CH₃COONa, 0.1 g MgSO₄·7H₂O, 0.5 g NaCl, and 2 mL of trace element solution to 1 L of distilled water. Adjust the pH of the solution to 7.2-7.4. Use ammonium sulfate ((NH₄)₂SO₄) as the sole nitrogen source, and control the initial nitrogen content of the culture medium to 100 mg / L.
[0031] S2: 3% or 5% ATP, aATP, aATP / cellulose, and N-aATP / cellulose were added to the culture medium as carrier materials, and then Bacillus cabrialesii bacteria were inoculated into the culture medium and cultured at a temperature of 37°C and a stirring speed of 165 rpm / min for 48 hours.
[0032] S3: To determine the ammonia nitrogen removal rate, centrifuge the bacterial culture at 10,000 rpm / min for 10 minutes to ensure separation of the bacteria and carrier from the solution. Aspirate the supernatant and determine the residual nitrogen content using Nessler's reagent spectrophotometry. Add equal amounts of potassium sodium tartrate and Nessler's reagent to the test solution, mix and shake, then let it stand for 10 minutes. Finally, measure the absorbance at a wavelength of 420 nm using a UV-Vis spectrophotometer (UV-3600, SHIMADZU) to determine the residual ammonia nitrogen concentration.
[0033] Experimental results showed that the ammonia nitrogen degradation rate of the blank group (no carrier added) was 58.2%. Adding 3% or 5% ATP did not significantly improve the ammonia nitrogen degradation ability of Bacillus cabrialesii (59.5% in the 3% group and 61.8% in the 5% group). However, when 3% aATP, aATP / cellulose, and N-aATP / cellulose were added, the ammonia nitrogen degradation rates increased to 78.3%, 82.1%, and 86.6%, respectively. When 5% aATP, aATP / cellulose, and N-aATP / cellulose were added, the ammonia nitrogen degradation rates further increased to 82.7%, 90.3%, and 96.9%, respectively. These experimental results validated the effectiveness of the attapulgite / cellulose composite aerogel as a microbial carrier. The N-aATP / cellulose composite aerogel exhibited the highest ammonia nitrogen degradation rate of 96.9% when added at a 5% concentration, significantly outperforming the other materials.
[0034] The nitrided attapulgite / cellulose composite aerogel materials prepared in Examples 1-4 above all have similar microstructures. As an effective carrier of microorganisms, the nitrided attapulgite / cellulose composite aerogel can effectively improve the degradation performance of Bacillus cabrialesii bacteria on ammonia nitrogen in water.
[0035] Although the present invention has been described above with reference to embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present invention. In particular, as long as there are no structural conflicts, the various features of the embodiments disclosed herein may be combined with each other in any manner, and the omission of an exhaustive description of such combinations in this specification is solely for the sake of space and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
Claims
1. A method for preparing a nitrided attapulgite / cellulose composite aerogel, characterized in that: Here are the steps: S1. Add the attapulgite into concentrated hydrochloric acid, stir and disperse, heat in a water bath and let stand, then filter, wash until neutral, and vacuum dry to obtain an acidified attapulgite; S2, adding the acidified attapulgite to a cellulose nanofiber aqueous solution containing a nitrogen source according to a mass ratio, stirring and ultrasonically treating the mixture, and then freezing the mixed solution and freeze-drying it to obtain an attapulgite / cellulose composite aerogel; S3. Placing the attapulgite / cellulose composite aerogel in a tubular furnace and calcining the attapulgite / cellulose composite aerogel under nitrogen protection to obtain a nitrided attapulgite / cellulose composite aerogel.
2. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 1, characterized in that: In step S1, the mass volume ratio of the attapulgite to concentrated hydrochloric acid is 1 g:30 mL-100 g:30 mL, and the concentration of the concentrated hydrochloric acid is 36.5%.
3. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 1, characterized in that: In step S1, the water bath heating time is 6 hours, the standing time is 24 hours, and the vacuum drying temperature is 60°C.
4. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 1, wherein: In step S2, the mass ratio of acidified attapulgite to cellulose nanofibers is 1:1-4:1, the concentrations of nitrogen source and cellulose nanofiber aqueous solution are 1-100 mg / mL, respectively, the ultrasonic treatment time is 10-30 min, the freeze-drying conditions are -80 to -60 ° C, and the freeze-drying time is 48 h.
5. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 1, characterized in that: The nitrogen source is one or more of urea, cyanuric acid and melamine.
6. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 1, characterized in that: In step S3, the heating rate is 5°C / min, the calcination temperature is 150-800°C, and the holding time is 1-4h.
7. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 1, characterized in that: In the nitrided attapulgite / cellulose composite aerogel, cellulose constitutes the aerogel skeleton, and the attapulgite is dispersed in the cellulose skeleton. When the concentration of CNF aqueous solution is 1-100 mg / mL and the mass ratio of acidified attapulgite to cellulose nanofibers is 1:1-4:1, it has a cellulose microtubule structure.
8. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 1, characterized in that: The prepared nitrided attapulgite / cellulose composite aerogel is used as a microbial carrier in wastewater treatment.
9. The method for preparing a nitrided attapulgite / cellulose composite aerogel according to claim 8, characterized in that: The microorganism is Bacillus cabrialesii bacteria, which is used to improve the bacteria's ability to degrade ammonia nitrogen.