Magnetic water supply sludge catalytic material and preparation method thereof

Abstract

The invention relates to a magnetic water supply sludge catalytic material and a preparation method thereof.The preparation method comprises the steps that water supply sludge, cement, water glass and sodium bicarbonate are mixed according to a first proportion on the basis of the ultrasonic condition, and a first sample is obtained; drying, granulating and carbonizing the first sample to obtain a second sample; mixing the second sample with an iron-containing compound to obtain a third sample, and performing reduction reaction and washing on the third sample to obtain the magnetic water supply sludge catalytic material. According to the scheme provided by the invention, waste utilization of the sludge can be realized, the recycling rate of the sludge is increased, and the nano-scale magnetite on the surface of the generated material has a high specific surface area and can provide a catalytic action for a subsequent oxidation process of water treatment.

Description

Technical Field

[0001] This application relates to the technical field of catalysts, and particularly to a magnetic water supply sludge catalytic material and a preparation method thereof. Background Art

[0002] Water supply sludge is an inevitable by-product in the process of water production in urban water treatment plants. Its main components are impurities in raw water, such as inorganic particles, plant residues, humus, adsorbed soluble metal salts and gases, etc., as well as various flocculants added in the water treatment process. The organic matter content is about 9% - 29%, and a large amount of silicon, iron, aluminum and a small amount of other components are contained in its inorganic components.

[0003] Compared with the sludge of sewage treatment plants, the environmental harm of water supply sludge is relatively small. Therefore, the treatment and disposal of water supply sludge have not been taken seriously enough. At present, most water treatment plants landfill the water supply sludge or directly discharge it into the nearby water bodies, which is likely to cause secondary pollution.

[0004] At present, the commonly used water supply sludge treatment technologies at home and abroad are similar to the sewage sludge pretreatment technologies, mainly including concentration, conditioning and dehydration, etc. The water supply sludge is dehydrated by means of dosing conditioning and mechanical dehydration, but these traditional dehydration means are time-consuming and laborious, and the dehydration effect is not ideal, and the treatment products still need to be further disposed of. Summary of the Invention

[0005] To solve or partially solve the problems existing in the related technologies, this application provides a magnetic water supply sludge catalytic material and a preparation method thereof, which can realize the waste utilization of water supply sludge, improve the recycling rate of water supply sludge, and the nano-scale magnetite particles loaded on the surface of the generated magnetic water supply sludge catalytic material can be combined with the conventional water treatment process to provide a catalytic effect and improve the removal efficiency of pollutants in sewage.

[0006] The first aspect of this application provides a preparation method of a magnetic water supply sludge catalytic material, including mixing water supply sludge, cement, water glass and sodium bicarbonate in a first ratio under ultrasonic conditions to obtain a first sample; drying, granulating and carbonizing the first sample to obtain a second sample; mixing the second sample with an iron-containing compound to obtain a third sample, and performing a reduction reaction and washing on the third sample to obtain the magnetic water supply sludge catalytic material.

[0007] In combination with the first aspect, in a possible implementation manner of the first aspect, the first ratio of the water supply sludge (dry basis), cement, water glass and sodium bicarbonate is (0.35 - 0.6):(0.1 - 0.3):(0.1 - 0.2):(0.05 - 0.15).

[0008] In combination with the first aspect, in a possible implementation manner of the first aspect, the ratio of the cement to the sodium silicate is (1 - 1.5):1.

[0009] In combination with the first aspect, in a possible implementation manner of the first aspect, the first sample is dried to a moisture content of 70% - 85%; the dried first sample is granulated to obtain the second sample with a particle size of 25 - 75 mm.

[0010] In combination with the first aspect, in a possible implementation manner of the first aspect, the carbonization time is 30 - 60 min, and the carbonization temperature is 350 - 450 °C.

[0011] In combination with the first aspect, in a possible implementation manner of the first aspect, the reduction reaction of the third sample includes: mixing and stirring the third sample with wood vinegar in a second ratio under ultrasonic conditions, and placing it in a reaction kettle to react at 190 - 220 °C for 12 - 20 h.

[0012] In combination with the first aspect, in a possible implementation manner of the first aspect, the second ratio of the third sample to the wood vinegar is 1 g:(10 - 25) ml.

[0013] In combination with the first aspect, in a possible implementation manner of the first aspect, the ratio of the second sample to the iron-containing compound is 1:(0.4 - 0.6).

[0014] The second aspect of the present application provides a magnetic water supply sludge catalytic material, which is prepared by using the preparation method described above.

[0015] The technical solution provided by the present application may include the following beneficial effects:

[0016] The magnetic water supply sludge catalytic material and its preparation method of the present application include: mixing water supply sludge, cement, sodium silicate and sodium bicarbonate in a first ratio under ultrasonic conditions to obtain a first sample; drying, granulating and carbonizing the first sample to obtain a second sample; mixing the second sample with an iron-containing compound to obtain a third sample, and performing a reduction reaction and washing on the third sample to obtain a magnetic water supply sludge catalytic material, which can realize the waste utilization of water supply sludge, improve the recycling rate of water supply sludge, and the nano-scale magnetite particles loaded on the surface of the generated magnetic water supply sludge catalytic material can be combined with conventional water treatment processes to provide a catalytic effect and improve the removal efficiency of pollutants in sewage.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. Description of the Drawings

[0018] The above and other objects, features, and advantages of the present application will become more apparent by describing the exemplary embodiments of the present application in more detail with reference to the accompanying drawings, wherein in the exemplary embodiments of the present application, the same reference numerals generally represent the same components.

[0019] Figure 1 is a schematic structural diagram of the magnetic feed water sludge catalytic material shown in the embodiment of the present application;

[0020] Figure 2 is a schematic structural diagram of the second sample shown in the embodiment of the present application;

[0021] Figure 3 is an X-ray diffraction pattern of the magnetic feed water sludge catalytic material A1 shown in the embodiment of the present application;

[0022] Figure 4 is a TEM image of the magnetite surface-loaded on the magnetic feed water sludge catalytic material A1 shown in the embodiment of the present application;

[0023] Figure 5 is an X-ray diffraction pattern of the feed water sludge catalytic material B1 shown in the embodiment of the present application. Detailed Embodiments

[0024] Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0025] The terms used in the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "the", and "said" used in the present application and the appended claims are also intended to include the plural forms unless the context clearly dictates 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.

[0026] It should be understood that although the terms "first", "second", "third", etc. may be used in the present application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0027] In the related art, the main components of feedwater sludge are impurities in raw water, such as inorganic particulate matters, plant residues, humus, adsorbed soluble metal salts and gases, etc., as well as various flocculants added during the water treatment process. Among them, the organic matter content is about 9% - 29%, and its inorganic components contain a large amount of silicon, iron, aluminum and a small amount of other components.

[0028] In the related art, the treatment and disposal of feedwater sludge have not been taken seriously enough. At present, most water treatment plants simply dehydrate the feedwater sludge and then landfill it or directly discharge it into the nearby water body, which is likely to cause secondary pollution. Therefore, it is necessary to treat the feedwater sludge and improve the treatment efficiency of the feedwater sludge.

[0029] In view of the above problems, the embodiments of the present application provide a magnetic feedwater sludge catalytic material and a preparation method thereof, which can realize the waste utilization of sludge, improve the recycling rate of sludge, and the nano - level magnetite particles loaded on the surface of the generated magnetic feedwater sludge catalytic material can be combined with conventional water treatment processes to provide a catalytic effect and improve the removal efficiency of pollutants in sewage.

[0030] The technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0031] The embodiments of the present application provide a preparation method of a magnetic feedwater sludge catalytic material, including:

[0032] S110: Mix feedwater sludge, cement, water glass and sodium bicarbonate in a first ratio under ultrasonic conditions to obtain a first sample.

[0033] According to some embodiments of the present application, in this step, feedwater sludge, cement, water glass and sodium bicarbonate are provided. The main components of feedwater sludge are impurities in raw water, such as inorganic particulate matters, plant residues, humus, adsorbed soluble metal salts and gases, etc., as well as various flocculants added during the water treatment process. Among them, the organic matter content is about 9% - 29%, and its inorganic components contain a large amount of silicon, iron, aluminum and a small amount of other components, and the harmful components are extremely low. The inorganic materials therein have a certain hardness and can be used as a catalyst substrate, while the variable - valence metals such as iron and aluminum salts are good adsorption and catalytic materials, which can provide reaction sites through valence changes during the catalytic oxidation reaction process and strengthen the oxidation reaction process. Therefore, this characteristic of feedwater sludge can be utilized to generate a magnetic feedwater sludge catalytic material as a catalyst substrate.

[0034] According to some embodiments of the present application, the water content of the feed sludge is 90-99%, and it contains SiO2, Fe2O3 and Al2O3. Among them, the contents of SiO2, Fe2O3 and Al2O3 are 30-70%, 10-35%, and 10-35% respectively. Under the ultrasonic condition with an ultrasonic power of 100-400W, the feed sludge, cement, water glass, and sodium bicarbonate are mixed and stirred evenly according to the first ratio. Among them, the first ratio of the feed sludge (dry basis), cement, water glass, and sodium bicarbonate can be (0.35-0.6):(0.1-0.3):(0.1-0.2):(0.05-0.15), and the sum of each component is 100%.

[0035] Specifically, during the mixing process, cement and water glass can be used as binders. Cement and water glass can form a cement-water glass double liquid, which can promote the rapid setting of the material, enhance the overall strength of the material, and prevent the material from disintegrating. Among them, the mass ratio of cement to water glass can be (1-1.5):1, and sodium bicarbonate can be used as a pore-forming agent; water glass is an aqueous solution of sodium silicate (Na2SiO3), which is a glassy viscous substance. It will precipitate a colloidal precipitate when encountering acid or standing for a long time. The main components after the hardening of water glass are silicon dioxide gel and silicon oxide. It has a large specific surface area, so it has relatively high adhesion and strength, and can resist almost all inorganic and organic acids except hydrofluoric acid (HF), hot phosphoric acid, and higher fatty acids. The silicon dioxide network skeleton formed after hardening has little strength reduction at high temperatures. When using heat-resistant refractory aggregates to prepare water glass mortar and concrete, the heat resistance can reach 1000℃.

[0036] S120: Dry, granulate, and carbonize the first sample to obtain the second sample.

[0037] As Figure 2 shown, specifically, after obtaining the first sample, the first sample can be dried to a water content of 70%-85%. After the drying is completed, the dried first sample can be put into a granulator for granulation. Samples with a particle size of 25-75 mm can be granulated. By granulating through a granulator, the first sample can be granulated into a spherical shape, which can better expand the specific surface area of the first sample.

[0038] Specifically, after granulation, the granulated first sample can be placed in a preheated muffle furnace and carbonized at 350-450 °C in an inert gas environment for 30-60 minutes. This can decompose the sodium bicarbonate in the first sample to form pores and preliminarily carbonize the organic matter to obtain the second sample, and then the second sample is cooled to room temperature.

[0039] S130: Mix the second sample with an iron-containing compound to obtain the third sample, and perform a reduction reaction and washing on the third sample to obtain the magnetic feed sludge catalytic material.

[0040] As Figure 1 shown, specifically, the iron-containing compound can be a compound containing trivalent iron such as steel slag. After mixing the third sample and the iron-containing compound, wood vinegar is added, and the mixture is stirred under ultrasonic conditions for 10-30 min. Subsequently, it is placed in a polytetrafluoroethylene autoclave and reacted at 190-220 °C for 12-20 h. After cooling to room temperature, the third sample can be obtained. The third sample is rinsed with absolute ethanol and dried to finally obtain a magnetic water supply sludge catalytic material uniformly loaded with nanometer magnetite.

[0041] Specifically, steel slag can supplement Fe element in the reaction system, and CaO therein can also serve as the framework for the synthesis reaction, enabling more nanometer magnetite particles to be loaded on the water supply sludge catalytic material.

[0042] Specifically, wood vinegar, also known as pyroligneous acid or wood acetic acid, is a liquid product obtained by the dry distillation of wood. It is a reddish-brown liquid after clarifying and separating the precipitated wood tar. The main component of wood vinegar is water, and it also contains wood tar (including water-soluble and water-insoluble ones), acetic acid, methanol, acetone, and a small amount of other chemical products. If wood vinegar is left standing for some time, it will separate into two layers, one layer containing water-soluble tar and the other layer containing the remaining chemical products. In this embodiment, wood vinegar contains a large amount of organic small molecule acids, which can decompose to generate CO in an anoxic environment and reduce Fe 3+ to Fe 2+ , and can synthesize nanometer magnetite on the second sample to obtain a magnetic water supply sludge catalytic material.

[0043] In another aspect of the present application, the present application proposes a magnetic water supply sludge catalytic material prepared by the above preparation method. Thus, this magnetic water supply sludge catalytic material has all the characteristics and advantages of the foregoing method and will not be elaborated herein. Compared with ordinary catalytic materials, the magnetic water supply sludge catalytic material in this embodiment is surface-loaded with magnetite and has a certain magnetism, which is convenient for the recycling and reuse of the material. In addition, Fe 2+ and Fe 3+ in magnetite serve as active sites in the reaction system, which can significantly promote the efficiency of redox reactions. This preparation method prepares a water supply sludge-based catalytic material loaded with nanometer magnetite by hydrothermal method, provides reaction sites with a high specific surface area, can catalytically enhance the reaction efficiency of redox reactions, and at the same time realizes the resource utilization of water supply sludge; the synthesized water supply sludge material has magnetism, is convenient for recycling and reuse, and the synthesis preparation method is simple and feasible, with the potential for industrial utilization.

[0044] It should be noted that the preparation method of the above magnetic water supply sludge catalytic material can refer to some or all of the steps in the foregoing preparation method. The relevant parameters of the above magnetic water supply sludge catalytic material can refer to some or all of the technical features in the foregoing embodiments. For the parts not described in the embodiments of the magnetic water supply sludge catalytic material, reference can also be made to the foregoing embodiments and the related drawings, which will not be elaborated here.

[0045] In another aspect of the present application, the present application proposes an application of a magnetic water supply sludge catalytic material. The magnetic water supply sludge catalytic material can be combined with conventional water treatment processes to provide a catalytic effect and improve the removal efficiency of pollutants in sewage.

[0046] The solution of the present application will be described below through specific embodiments. It should be noted that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specifying specific technologies or conditions in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0047] Example 1

[0048] Preparation of the first sample:

[0049] 1 kg of 42.5-type cement, 0.8 kg of water glass, and 0.5 kg of sodium bicarbonate were respectively added to 20 kg of water supply sludge with a water content of 90%. The first ratio of water supply sludge (dry basis), cement, water glass, and sodium bicarbonate was: 0.46:0.23:0.19:0.12. Mixing was carried out under ultrasonic conditions of 40 kHz, with an ultrasonic power of 270 W, and stirring for 30 min to obtain the first sample.

[0050] Preparation of the second sample:

[0051] The first sample was dried to a water content of 80%, then put into a granulator for granulation, with an average particle size of 35 mm. Subsequently, the material was placed in a preheated muffle furnace and calcined at 400 °C under an inert gas environment for 40 min to decompose the sodium bicarbonate in the material to form pores and preliminarily carbonize the organic matter. After completion, it was naturally cooled to room temperature to obtain the second sample.

[0052] Preparation of the magnetic water supply sludge catalytic material:

[0053] Mix 1 kg of the second sample with 0.5 kg of steel slag. Mix the resulting mixed solid with 23 L of wood vinegar under ultrasonic conditions of 40 kHz for 20 min. The ultrasonic power is 200 W. Then place it in a polytetrafluoroethylene high-pressure reactor and react at 200 °C for 15 h. After cooling to room temperature, a third sample can be obtained. Rinse the third sample with absolute ethanol and transfer it to an oven at 75 °C for drying for 8 h. Finally, a magnetic feedwater sludge catalytic material A1 is obtained, as Figure 3 and Figure 4 shown Figure 3 and Figure 4 are the X-ray diffraction pattern and the TEM image of surface-loaded magnetite of the magnetic feedwater sludge catalytic material A1, respectively.

[0054] Example 2

[0055] This example provides the first sample, the second sample, the third sample, and the magnetic feedwater sludge catalytic material. The preparation method is basically the same as that of Example 1, except that in the preparation of the first sample, the first ratio of feedwater sludge (dry basis), cement, water glass, and sodium bicarbonate is 0.4:0.3:0.2:0.1.

[0056] Comparative Example 1:

[0057] This comparative example provides the first sample, the second sample, the third sample, and the magnetic feedwater sludge catalytic material. The preparation method is basically the same as that of Example 1, except that in the preparation of the second sample, no steel slag is added and it is directly processed to obtain a feedwater sludge catalytic material B1, as Figure 5 shown, which is the X-ray diffraction pattern of the feedwater sludge catalytic material B1.

[0058] Comparative Example 2:

[0059] This comparative example provides the first sample, the second sample, the third sample, and the magnetic feedwater sludge catalytic material. The preparation method is basically the same as that of Example 1, except that the first ratio of feedwater sludge (dry basis), cement, water glass, and sodium bicarbonate is: 0.7:0.15:0.1:0.05, and a feedwater sludge catalytic material B2 is obtained.

[0060] Comparative Example 3:

[0061] This comparative example provides the first sample, the second sample, the third sample, and the magnetic feedwater sludge catalytic material. The preparation method is basically the same as that of Example 1, except that the wood vinegar is replaced with the same amount of 0.02 mol / L dilute hydrochloric acid to obtain a feedwater sludge catalytic material B3.

[0062] Comparative Example 4:

[0063] In 20 kg of feed sludge with a water content of 90%, it was dried to a water content of 80%, then put into a granulator for granulation, with an average particle size of 35 mm. Subsequently, the material was placed in a preheated muffle furnace and calcined at 800 °C under an inert gas environment for 60 min. After completion, it was naturally cooled to room temperature to obtain the sludge pyrolysis biochar material B4.

[0064] Test methods:

[0065] 1. The particle size, specific surface area, and the particle size of the surface-loaded magnetite of the feed sludge catalytic materials obtained in each example and comparative example were respectively tested, and the results are shown in Table 1. Among them, the particle size, specific surface area, and the particle size of the surface-loaded magnetite were determined by screening method, BET specific surface area detection method, and TEM statistics method respectively.

[0066] Table 1

[0067]

[0068] 2. Using the feed sludge catalytic materials obtained in each example and comparative example, catalytic ozonation was used to treat high-concentration refractory wastewater. Specifically: the catalytic material was placed in a porous box or mesh bag and fixed at 300 mm from the ozone outlet. The material accounted for 35 - 50% of the total volume of the treatment facility. The specific treatment effects are shown in Table 2.

[0069] Table 2

[0070]

[0071] 3. In the above experiments, compared with the reaction system without using a catalyst, after adding the catalytic materials synthesized in each example and comparative example, the percentage increase in the accumulation amount of ·OH in the system and the recovery rate of recovering the materials with a magnet after the reaction are shown in Table 3.

[0072] Table 3

[0073]

[0074] As can be seen from Table 1, magnetite particles were not successfully loaded on the surfaces of materials B1 and B3. Due to the relatively high proportion of feed sludge in the synthesis raw materials of B2, the strength of the first synthesized sample was low, resulting in unstable granulation, easy disintegration of the particles, and less magnetite loaded on the surface. During the synthesis of material B3, dilute hydrochloric acid was used instead of wood vinegar, and there was a lack of a reducing environment during the synthesis of the third sample, so magnetite could not be synthesized, but nano-scale hematite (Fe2O3, particle size of 15 ± 4 nm) was synthesized. Material B4 was directly made into biochar by pyrolyzing feed sludge, was powdery, had a relatively large specific surface area, and A1 - A3, B3, and B4 all had a relatively high specific surface area.

[0075] As can be seen from Table 2, the initial COD concentration was 15000 mg / L, the initial antibiotic concentration was 10 mg / L of tetracycline, and the initial concentration of resistance genes was 10.7 x 10 10 copies / L. By comparing Examples 1-3 with Comparative Examples 1-4, it can be seen that samples A1-A3 had a higher pollutant removal rate compared to B1-B4, and the magnetic feedwater sludge catalytic materials A1-A3 could significantly improve the efficiency of the ozone oxidation reaction.

[0076] As can be seen from Table 3, by comparing Examples 1-3 with Comparative Examples 1-4, the percentage increase in the production of ·OH by A1-A3 was all above 40%, while B1-B4 could only increase the production of ·OH to a relatively low level, with the percentage increase all below 23%, and the magnetic recovery rate was relatively low. The magnetic feedwater sludge catalytic materials A1-A3 could significantly improve the catalytic decomposition of ozone to generate ·OH, improve the oxidation efficiency of ozone, and had a high magnetic recovery rate.

[0077] In summary, by reacting the feedwater sludge with iron-containing compounds, magnetic feedwater sludge catalytic materials are obtained, which can realize the waste utilization of feedwater sludge, improve the recycling rate of feedwater sludge, and the nano-scale magnetite particles loaded on the surface of the generated magnetic feedwater sludge catalytic materials can be combined with conventional water treatment processes to provide a catalytic effect and improve the removal efficiency of pollutants in sewage.

[0078] The embodiments of the present application have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technologies in the market, or to enable other ordinary skill in the art in the technical field to understand the embodiments disclosed herein.

Claims

1. A method for preparing a magnetic water supply sludge catalytic material, characterized in that: include: Mixing water supply sludge, cement, water glass and sodium bicarbonate in a first ratio under ultrasonic conditions to obtain a first sample; Drying, granulating and carbonizing the first sample to obtain a second sample; The second sample is mixed with an iron-containing compound to obtain a third sample, and the third sample is subjected to a reduction reaction and washed to obtain the magnetic water supply sludge catalytic material.

2. The method according to claim 1, characterized in that The first ratio of the water supply sludge, cement, water glass and sodium bicarbonate is (0.35-0.6): (0.1-0.3): (0.1-0.2): (0.05-0.15).

3. The method according to claim 2, characterized in that The ratio of cement to water glass is (1-1.5):

1.

4. The method according to claim 1, characterized in that: Drying the first sample to a moisture content of 70%-85%; The first sample after drying is granulated to obtain the second sample with a particle size of 25-75 mm.

5. The method according to claim 1, characterized in that The carbonization time is 30-60 minutes, and the carbonization temperature is 350-450°C.

6. The method according to claim 1, characterized in that The reducing reaction of the third sample comprises: The third sample and wood acetic acid are mixed and stirred in a second ratio under ultrasonic conditions, and placed in a reactor to react at 190-220° C. for 12-20 h.

7. The method according to claim 1, characterized in that The second ratio of the third sample to the wood acetic acid is 1 g: (10-25) ml.

8. The method according to claim 1, characterized in that The ratio of the second sample to the iron-containing compound is 1:(0.4-0.6).

9. A magnetic water supply sludge catalytic material, characterized in that: The method is prepared by any one of claims 1 to 8.

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