Method for preparing magnetic adsorbent from tea residues
Converting tea waste into magnetic iron oxide adsorbents through thermal treatment and pH-controlled co-precipitation addresses the environmental and resource waste issues of tea waste disposal, achieving efficient heavy metal removal with minimal sedimentation and pollution.
Patent Information
- Application Number
- CN202510754382.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-06
- Publication Date
- 2025-07-15
AI Technical Summary
As agricultural and forestry waste, tea residues are not effectively utilized, resulting in environmental pollution. At the same time, activated carbon prepared from existing tea residues has difficulty in separating mud and water and secondary pollution when used for heavy metal wastewater treatment.
After the tea residue is prepared into activated carbon, a magnetic ferrite adsorbent is synthesized with a divalent iron source at room temperature. Through pyrolysis and co-precipitation reaction, a magnetic adsorbent that is easy to separate is prepared for heavy metal wastewater treatment.
The resource utilization of tea residues has been achieved, which effectively removes heavy metal ions, reduces the amount of sludge residue, avoids the difficulty of separating mud and water, and protects the environment.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of adsorbents, and particularly to a method for preparing a magnetic adsorbent using tea residues. Background Art
[0002] With the rapid development of the tea industry, the output of tea residues has been increasing year by year during the processes of tea planting, processing and consumption. As a kind of agricultural and forestry waste, most of the tea residues are currently directly discarded or burned. If not effectively utilized and improperly treated, it will not only cause a large amount of resource waste, but also increase the load on the ecological environment and cause environmental pollution, especially the impact on the aquatic environment. Therefore, the treatment of tea residues has become an important ecological and environmental issue.
[0003] Since tea residues contain relatively high amounts of valuable substances such as proteins, tea polyphenols, and cellulose, they are mostly used as fertilizers, feed additives, and in the pharmaceutical industry, etc. In addition, tea residues have a high fixed carbon content, well-developed pores, a large specific surface area, high output, easy collection, and low price, etc., and are an ideal raw material for preparing activated carbon adsorbents. However, when the activated carbon prepared from tea residues is directly applied to the treatment of heavy metal wastewater, there are problems such as poor separation of mud and water; and poor sedimentation of the adsorbent, resulting in a large amount of sludge after treatment, which is likely to cause secondary pollution to the environment. Based on this, the present invention prepares a magnetic ferrite by combining the activated carbon prepared from tea residues with a divalent iron source and applies it to the treatment of heavy metal wastewater, which can be used as a new way for the resource utilization of tea residues. Ferrites have unique magnetism, making it easy to separate from water, with less sludge production, and the ferrite preparation process is simple and easy to operate, and it can be industrially produced in the future.
[0004] Currently, the discharge of industrial wastewater containing heavy metals is large, causing relatively serious environmental pollution. However, if tea residues can be efficiently applied to the treatment of industrial wastewater, it will not only protect the environment but also solve the problem of the utilization of a large amount of tea residues. Summary of the Invention
[0005] In view of the large increase in the amount of tea residues polluting the environment, as well as its characteristics such as high fixed carbon content, large specific surface area, and low cost, the present invention proposes a technical idea of first preparing activated carbon from tea residues and then synthesizing a magnetic ferrite adsorbent by combining the prepared activated carbon with a divalent iron source. The tea residues are prepared into activated carbon by pyrolysis, and then at room temperature, the activated carbon and the divalent iron source are synthesized into a magnetic ferrite with good adsorption performance and stable properties under the action of coprecipitation, which is directly applied to the treatment of heavy metal wastewater. The heavy metal ions in the treated wastewater can meet the discharge standards, and the amount of sludge is small, avoiding the problem of difficult separation of mud and water, and realizing the effective resource utilization of tea residues.
[0006] To achieve the above object, the present invention is realized through the following technical solutions:
[0007] The present invention discloses a method for preparing a magnetic adsorbent from tea residues. After pyrolyzing the tea residues, under normal temperature and nitrogen atmosphere, the pyrolyzed tea residues are mixed with a divalent iron source and water, followed by a water bath reaction, and the pH is adjusted to 8.0 - 10.0. After the reaction is completed, vacuum drying is carried out to obtain the adsorbent.
[0008] Preferably, the pyrolysis temperature of the tea residues is 400 - 800 °C, and the time is 1 - 3 h.
[0009] Preferably, nitrogen is introduced into water at a flow rate of 1.0 L / min for 6 - 8 min.
[0010] Preferably, the tea residues are dried at 60 - 100 °C for 2 - 5 h, crushed to 120 - 180 mesh, and then pyrolyzed.
[0011] Preferably, the mass ratio of the pyrolyzed tea residues to the divalent iron source is 0.5 - 2:1, and the mass concentration of the divalent iron source is 5 g / L.
[0012] Preferably, the water bath temperature is 25 - 30 °C, the time is 1 h, and the stirring speed is 800 r / min.
[0013] Preferably, the temperature of the vacuum drying is 50 - 70 °C, and the drying time is 2 - 4 h.
[0014] Correspondingly, an application of the magnetic adsorbent prepared by the above preparation method in treating cadmium-containing wastewater.
[0015] Preferably, the dosage of the magnetic adsorbent is 0.05 g / L, and the concentration of cadmium ions is 300 mg / L.
[0016] The present invention has the following beneficial effects:
[0017] The present invention proposes a new way for the resource utilization of tea residues: in the past, some effective components in tea residues were widely used in industries such as agriculture, livestock and poultry breeding, and medicine and food. Some used its high carbon content and good adsorption performance to prepare carbon products directly for adsorbing heavy metals. However, there are problems such as fine carbon particle suspensions in the treated wastewater, large amounts of mud residues, and difficulty in separating mud and water. The present invention synthesizes a ferrite adsorbent by preparing activated carbon from tea residues and a divalent iron source, which not only utilizes the easy source and strong adsorption performance of tea residues, but also endows the material with strong magnetic properties. Specific embodiments
[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0019] If not specifically specified, the technical means used in the implementation examples are conventional means well-known to those skilled in the art.
[0020] The present invention discloses a method for preparing a magnetic adsorbent using tea residues, and the steps are as follows:
[0021] 1) First, put the tea residues into an oven set at a temperature of 80 °C for drying for 3 h. Subsequently, crush the dried tea residues, and the particle size is about 150 mesh.
[0022] 2) Place the crushed tea residue particles in a crucible and directly put them into a muffle furnace for pyrolysis to make activated carbon. The pyrolysis temperature is 600 °C and the time is 1.5 h.
[0023] 3) Under normal temperature conditions, add a certain amount of distilled water to a reaction flask, introduce nitrogen at a flow rate of 1.0 L / min for 6 - 8 min to retain an appropriate amount of dissolved oxygen in the water; after introducing nitrogen, add the prepared activated carbon and divalent iron source to the distilled water for mixing according to a certain ratio. The mass ratio of the activated carbon to the divalent iron source is 0.5 - 2:1, and the mass concentration of the divalent iron source is 5 g / L. The divalent iron source includes but is not limited to FeSO4 and FeCl2.
[0024] 4) Put the mixed solution into a constant temperature water bath magnetic stirrer for reaction. The water bath temperature is 25 - 30 °C (preferably 30 °C), the time is 1 h, the stirring speed is 800 r / min, and use sodium hydroxide and hydrochloric acid to adjust the pH value of the mixed solution to keep it at a constant value. The set range of the pH value is 8.0 - 10.0.
[0025] 5) Wash the prepared adsorbent repeatedly with deionized water and absolute ethanol respectively, and then put it into a vacuum drying oven for drying for subsequent characterization. The temperature setting range of the vacuum drying oven is 50 - 70 °C, and the drying time is 2 - 4 h.
[0026] 6) Treat the simulated cadmium-containing wastewater with the prepared magnetic adsorbent. The dosage of the adsorbent is 0.05 g / L, and the concentration of cadmium ions is 300 mg / L.
[0027] The present invention will be further elaborated below in conjunction with specific embodiments.
[0028] All the medicaments used in the following examples are commercially available
[0029] Example 1
[0030] A method for preparing a magnetic adsorbent using tea residue, the steps are as follows:
[0031] Under the condition of normal temperature 25 °C, according to the mass ratio of activated carbon to divalent iron ions of 1:1, 5.0 g of the activated carbon prepared in the above step 2) was weighed and added to a solution with an iron mass concentration of 5.0 g / L, and the pH was adjusted to 9.0 to synthesize the product. The synthesized product was separated from the solution by magnetic separation method, and the synthesized product was repeatedly washed with deionized water and absolute ethanol respectively, and then it was placed in a vacuum drying oven at a temperature of 60 °C for 2.5 h of drying. The obtained product was magnetite. Analyzed by the sedimentation rate of the product, the sedimentation rate was 90%.
[0032] The prepared adsorbent was applied to the treatment of simulated cadmium-containing wastewater, characterized by the removal rate of cadmium ions. The concentration of cadmium ions was 300 mg / L, the addition amount of the adsorbent was 0.05 g / L, and the cadmium ion removal rate was 99%.
[0033] Example 2
[0034] A method for preparing a magnetic adsorbent using tea residue, the steps are as follows:
[0035] Under the conditions of normal temperature and pH = 9.0, according to the mass ratio of activated carbon to divalent iron ions of 0.5:1, 2.5 g of the activated carbon prepared in the above step 2) was weighed and added to a solution with an iron mass concentration of 5 g / L for synthesis reaction. The synthesized product was separated from the solution by magnetic separation method, and the synthesized product was repeatedly washed with deionized water and absolute ethanol respectively, and then it was placed in a vacuum drying oven at a temperature of 60 °C for 2.5 h of drying. The obtained product was magnetite. Analyzed by the sedimentation rate of the product, the sedimentation rate was 91%. Due to the large amount of iron source added, its sedimentation rate was slightly higher than that of Example 1.
[0036] The prepared adsorbent was applied to the treatment of simulated cadmium-containing wastewater, characterized by the removal rate of cadmium ions. The concentration of cadmium ions was 300 mg / L, the addition amount of the adsorbent was 0.05 g / L, and the cadmium ion removal rate was 70%.
[0037] Example 3
[0038] A method for preparing a magnetic adsorbent using tea residue, the steps are as follows:
[0039] Under normal temperature and pH = 9.0 conditions, according to the mass ratio of activated carbon to divalent iron ions of 2:1, 10 g of the activated carbon prepared in step 2) above was weighed and added to a solution with an iron mass concentration of 5 g / L for synthesis reaction. The synthesis product was separated from the solution by magnetic separation method, and the synthesis product was repeatedly washed with deionized water and absolute ethanol respectively, and then placed in a vacuum drying oven at 60 °C for 2.5 h of drying. The obtained product was magnetite. Analyzed by the sedimentation rate of the product, the sedimentation rate was 30%.
[0040] The prepared adsorbent was applied to the treatment of simulated cadmium-containing wastewater, characterized by the removal rate of cadmium ions. The concentration of cadmium ions was 300 mg / L, the addition amount of the adsorbent was 0.05 g / L, and the cadmium ion removal rate was 100%.
[0041] The cadmium ion removal rate of the adsorbent prepared in Example 3 was slightly higher than that in Example 1, but a large amount of sludge was generated after treatment, and there were fine suspended particles in the treated wastewater.
[0042] The above-described embodiments are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.
Claims
1. A method for preparing a magnetic adsorbent using tea residues, characterized in that: After pyrolyzing the tea residue, at room temperature, mix the pyrolyzed tea residue with a divalent iron source and water, carry out a water bath reaction, and adjust the pH to 8.0 - 10.
0. After the reaction is completed, vacuum drying yields the adsorbent.
2. The method for preparing a magnetic adsorbent using tea residues according to claim 1, characterized in that: The pyrolysis temperature of the tea residue is 400 - 800 °C, and the time is 1 - 3 h.
3. The method for preparing a magnetic adsorbent using tea residue according to claim 1, characterized in that: Introduce nitrogen into water at a flow rate of 1.0 L / min for 6 - 8 min.
4. A method for preparing a magnetic adsorbent using tea residues according to claim 1 or 2, characterized in that: The tea residue is dried at 60 - 100 °C for 2 - 5 h, pulverized to 120 - 180 mesh, and then pyrolyzed.
5. A method for preparing a magnetic adsorbent using tea dregs according to claim 1, characterized in that: The mass ratio of the pyrolyzed tea residue to the divalent iron source is 0.5 - 2:1, and the mass concentration of the divalent iron source is 5 g / L.
6. A method for preparing a magnetic adsorbent using tea residues according to claim 1, characterized in that: The water bath temperature is 25 - 30 °C, the time is 1 h, and the stirring speed is 800 r / min.
7. A method for preparing a magnetic adsorbent using tea residues according to claim 1, characterized in that: The temperature of the vacuum drying is 50 - 70 °C, and the drying time is 2 - 4 h.
8. Application of the magnetic adsorbent prepared by the preparation method according to any one of claims 1 - 7 in treating cadmium-containing wastewater.
9. The application according to claim 8, characterized in that: The dosage of the magnetic adsorbent is 0.05 g / L, and the concentration of cadmium ions is 300 mg / L.