Magnetic composite material and preparation method and application thereof

Abstract

The invention discloses a magnetic composite material and a preparation method and application thereof.The method comprises the steps that a silicon modified biochar material is subjected to ultrasonic treatment and then completely distributed in an ethylene glycol solution, then MnCl24H2O and FeCl36H2O are added, stirring is conducted till complete dissolution is achieved, sodium acetate trihydrate and polyethylene glycol 2000 are added, stirring is conducted continuously, and a preliminary sample is obtained; and carrying out heating reaction on the preliminary sample, carrying out solid-liquid separation under the condition of an external magnetic field, washing with ethanol and clear water, and drying to obtain the magnetic composite material. The removal effect of the magnetic composite material on Cu (II) and TC is obviously influenced by the concentration of Cu (II) and TC in a solution, when the concentration of Cu (II) is certain, the adsorption rate on Cu (II) can be improved by increasing the concentration of TC, and the removal effect on Cu (II) is greatly improved.

Description

Technical Field

[0001] The invention relates to the field of wastewater pollution adsorption materials, and in particular to a preparation method and application of a magnetic composite material. Background Art

[0002] With the improvement of science and technology, a large amount of residual heavy metals and antibiotics will form complex pollution, causing long-term impacts on aquatic ecosystems, soil, groundwater and other environments. These pollutants interact with each other in wastewater, which may produce complex pollution effects and cause greater harm to the environment and ecology.

[0003] The pollution sources of heavy metal copper mainly come from two major fields: industry and agriculture. In industry, heavy metal pollution mainly comes from various industrial production processes, such as metallurgy, leather manufacturing, electroplating and mining. In the environment, heavy metals are persistent, resistant to degradation and bioaccumulative. If these wastes are not properly handled, they will pollute the surrounding environment. In agriculture, heavy metal pollution mainly comes from agricultural production activities, among which the feces and wastewater produced by livestock and poultry breeding are one of the main sources of pollution.

[0004] Tetracycline antibiotics are one of the most widely used antibiotics in animal husbandry and aquaculture. They are a class of highly effective antibiotics, including tetracycline (TC) and chlortetracycline, which can reduce or eliminate the activity of microorganisms and can therefore be used to treat a variety of diseases. However, the absorption and utilization efficiency of tetracycline antibiotics are quite low, and most antibiotics enter the natural environment through waste discharge, thereby polluting water sources and land environments. Tetracycline antibiotics remaining in the soil will be absorbed by vegetables and crops, and then absorbed by the human body in the food chain, which causes tetracycline to accumulate in the human body and eventually poses a threat to human health.

[0005] In the field of aquaculture, with the widespread use of tetracycline and heavy metal copper and the continuous expansion of aquaculture scale, serious pollution problems and a large amount of aquaculture wastewater have also arisen. As a result, the treatment of antibiotics and heavy metals has problems such as large emissions, wide pollution, high difficulty in treatment and complex processes. In particular, some heavy metals will react with antibiotics to form complex pollution.

[0006] In the composite system, antibiotics and heavy metals present a variety of complex interactions, which cause various degrees of joint toxicity to organisms, such as superposition, synergy and antagonism. When tetracycline is mixed with copper ions, the two may interact with each other to form complexes, and the complexation of pollutants may change the various effects of these polymers on the environment, and its toxicity is far greater than that of a single complex. In addition, when tetracycline coexists with copper and forms a coordination complex, it can accelerate the migration of copper pollution in the environment and trigger the formation of tetracycline resistance genes on a larger scale.

[0007] The current traditional treatment process is difficult to remove complex pollutants, and they are easy to be retained in the body, causing a series of health problems such as lesions. Therefore, it is urgent to develop a magnetic composite material that can simultaneously treat heavy metal and antibiotic complex pollution in water to solve the problems existing in the traditional treatment process. Summary of the invention

[0008] In view of the problems in the prior art, the present invention provides a magnetic composite material and a preparation method and application thereof to solve the problems in the prior art.

[0009] The present invention provides a method for preparing a magnetic composite material, the preparation method comprising: Weigh 500 mg of silicon-modified biochar material, distribute it completely in 40 mL of ethylene glycol solution after ultrasonication, and then add 0.0005 mol of MnCl 2 •4H 2 O and 0.001 mol FeCl 3 •6H 2 O, stirring until completely dissolved, adding 3.4 g of sodium acetate trihydrate and 1 g of polyethylene glycol 2000 and continuing stirring for a first preset time to obtain a preliminary sample; The preliminary sample is heated to react at a first preset temperature, and solid-liquid separation is performed under an external magnetic field condition, and the magnetic composite material is obtained after washing with ethanol and clean water and drying.

[0010] Furthermore, the ultrasonic time of the silicon-modified biochar material is 3 hours, the first preset time is 60 minutes, the first preset temperature is 200° C., and the heating reaction time of the preliminary sample is 12 hours.

[0011] Furthermore, the silicon-modified biochar material is SiO 2 / DBC, the preparation method thereof comprises: 10 g of natural montmorillonite is weighed and added into 250 mL of deionized water to form a montmorillonite suspension, and after ultrasonicating the montmorillonite suspension, 20 g of rice husk powder passed through a 40-mesh sieve is immersed in the suspension, and the solid is separated after magnetic stirring, and dried at a second preset temperature to obtain a preliminary solid; The preliminary solid is placed in a high-temperature muffle furnace filled with nitrogen and heated to a third preset temperature at a preset heating rate for pyrolysis, and then washed with deionized water and dried to obtain a silicon-modified biochar material.

[0012] Furthermore, the ultrasonic time of the montmorillonite suspension is 0.5 h, the magnetic stirring time is 2 h, and the second preset temperature is 50° C. to 70° C.

[0013] Furthermore, the preset heating rate is a constant 10°C / min, the third preset temperature is 500°C, and the pyrolysis time is 2h.

[0014] The present invention also provides a magnetic composite material, which is prepared by using the preparation method of the magnetic composite material.

[0015] According to the magnetic composite material proposed in the present invention, the magnetic composite material was characterized by SEM-EDS, VSM, BET, FTIR, XRD, TEM and XPS, and the structural morphology of the magnetic composite material was analyzed. It was found that the composite material has both catalytic and adsorption properties. At the same time, its treatment effect on binary composite pollution of Cu(II) and TC and its recycling and regeneration performance were explored. The removal effect of the magnetic composite material in the present application on Cu(II) and TC is significantly affected by the concentrations of Cu(II) and TC in the solution. When the concentration of Cu(II) is constant, increasing the concentration of TC will increase the adsorption rate of Cu(II), thereby greatly improving the removal effect of Cu(II).

[0016] The invention also proposes an application of a magnetic composite material in degrading copper and tetracycline pollutants in waste water.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 In the embodiment of the present invention, MnFe 2 O 4 、DBC / SiO 2 and MnFe 2 O 4 / DBC / SiO 2 Infrared spectrum of Figure 2 In the embodiment of the present invention, MnFe 2 O 4 and MnFe 2 O 4 / DBC / SiO 2 hysteresis loop of Figure 3 In the embodiment of the present invention, SiO 2 / DBC and MnFe 2 O 4 / DBC / SiO 2 N 2 Adsorption-desorption isotherms; Figure 4 In the embodiment of the present invention, SiO 2 / DBC and MnFe 2 O 4 / DBC / SiO 2 XRD pattern of Figure 5 The magnetic MnFe 2 O 4 / DBC / SiO 2 SEM images, EDS images and element mapping images; Figure 6 The different concentrations of Cu(II) on MnFe in the present invention are shown in Figure 2. 2 O 4 / DBC / SiO 2 Remove the effects of tetracycline; Figure 7 The different concentrations of tetracycline in the present invention are obtained to determine the effect of tetracycline on MnFe 2 O 4 / DBC / SiO 2 Effect of removing Cu(II); Figure 8 The diagram and EPR spectrum of the effect of free radical scavenger on tetracycline degradation in the embodiment of the present invention; Fig. 9 The magnetic MnFe 2 O 4 / DBC / SiO 2 Full spectra of C 1s, O 1s, Fe 2p, Mn2p, Si 2p, and Cu 2p before and after the reaction; Fig.10 In the embodiment of the present invention, MnFe 2 O 4 / DBC / SiO 2 Graph of the cycle regeneration performance.

[0020] The embodiments of the present invention will be further described below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] In order to make the purpose, 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 in conjunction with the examples. Several embodiments of the present invention are given in the examples. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0022] Example 1 In embodiment 1 of the present invention, a method for preparing a magnetic composite material is provided, and the preparation method comprises: Weigh 500 mg of silicon-modified biochar material, distribute it completely in 40 mL of ethylene glycol solution after ultrasonication, and then add 0.0005 mol of MnCl 2 •4H 2 O and 0.001 mol FeCl 3 •6H 2 O, stirring until completely dissolved, adding 3.4 g of sodium acetate trihydrate and 1 g of polyethylene glycol 2000 and continuing stirring for a first preset time to obtain a preliminary sample; The preliminary sample is heated to react at a first preset temperature, and solid-liquid separation is performed under an external magnetic field condition, and the magnetic composite material is obtained after washing with ethanol and clean water and drying.

[0023] Furthermore, the ultrasonic time of the silicon-modified biochar material is 3 hours, the first preset time is 60 minutes, the first preset temperature is 200° C., and the heating reaction time of the preliminary sample is 12 hours.

[0024] Specifically, in order to facilitate the description of the magnetic composite material provided by the present invention, the magnetic composite material is hereinafter referred to as MnFe 2 O 4 / DBC / SiO 2 , and the above silicon-modified biochar material is SiO 2 / DBC, the preparation method thereof is as follows: 10 g of natural montmorillonite is weighed and added into 250 mL of deionized water to form a montmorillonite suspension, and after ultrasonicating the montmorillonite suspension, 20 g of rice husk powder passed through a 40-mesh sieve is immersed in the suspension, and the solid is separated after magnetic stirring, and dried at a second preset temperature to obtain a preliminary solid; The preliminary solid is placed in a high-temperature muffle furnace filled with nitrogen and heated to a third preset temperature at a preset heating rate for pyrolysis, and then washed with deionized water and dried to obtain a silicon-modified biochar material.

[0025] Furthermore, the ultrasonic time of the montmorillonite suspension is 0.5 h, the magnetic stirring time is 2 h, and the second preset temperature is 50° C. to 70° C.

[0026] Furthermore, the preset heating rate is a constant 10°C / min, the third preset temperature is 500°C, and the pyrolysis time is 2h.

[0027] The main purpose of the preparation method provided in the above Example 1 is to improve the treatment effect and recycling regeneration performance of binary composite pollution of Cu(II) and TC.

[0028] Example 2 Embodiment 2 of the present invention provides a magnetic composite material, and the magnetic composite material is prepared by the preparation method of the magnetic composite material as described in Embodiment 1.

[0029] According to the magnetic composite material proposed in this embodiment, the magnetic composite material mainly utilizes magnetic MnFe 2 O 4 and silicon-modified biochar materials SiO 2 Preparation of MnFe by combining / DBC 2 O 4 / DBC / SiO 2 The composite material is prepared and used as a catalyst to enhance the adsorption capacity of Cu(Ⅱ), while the degradation effect of TC is greatly improved.

[0030] Example 3 Example 3 of the present invention provides an application of a magnetic composite material in degrading copper and tetracycline pollutants in wastewater.

[0031] In order to further illustrate the adsorption performance of the magnetic composite material provided in the above embodiments of the present invention, characterization analysis, adsorption performance analysis, catalytic mechanism analysis, and recycling regeneration performance analysis are performed on the magnetic composite material in the above embodiments of the present invention.

[0032] 1. Characterization analysis 1.1 FTIR analysis: Infrared spectroscopy is one of the common characterization methods used to analyze the functional groups on the surface of materials. 2 O 4 / DBC / SiO 2 The functional groups on the surface of the materials have different effects on DBC / SiO 2 , magnetic MnFe 2 O 4 and magnetic MnFe 2 O 4 / DBC / SiO 2 Infrared spectroscopy was performed. Figure 1 ,DBC / SiO 2 and MnFe 2 O4 / DBC / SiO 2 At 3460.03 cm -1 and 1620.20 cm -1 A broad peak appeared at 2 O 4 However, it tends to be flat and no peak appears, which is attributed to the stretching vibration of water molecules and OH functional groups. -1 and 470.68 cm -1 The peaks correspond to the stretching vibrations of the oxygen bonds of Fe and Mn metals, respectively. 2 O 4 The magnetic MnFe 2 O 4 / DBC / SiO 2 There also appeared magnetic MnFe 2 O 4 The same metal oxygen bond stretching vibration peak further indicates the successful preparation of magnetic MnFe 2 O 4 / DBC / SiO 2 Composite materials.

[0033] 1.2 VSM analysis: In order to explore whether MnFe 2 O 4 Composite to silicon modified biochar DBC / SiO 2 The prepared composite materials were characterized by VSM. Figure 2 It was observed that MnFe 2 O 4 The saturation magnetization of MnFe is 40.73 emu / g. 2 O 4 / DBC / SiO 2 The saturation magnetization of the 2 O 4 Loaded on modified biochar DBC / SiO 2 Therefore, the magnetism is greatly weakened. 2 O 4 / DBC / SiO 2 After being placed in water and stirred until turbid, a magnet was added to verify its magnetic separation ability. It was found that under the condition of applying an external magnetic field, the turbid mixed solution achieved solid-liquid separation within 3 minutes, making the solution clear. This shows that magnetic MnFe 2 O 4 / DBC / SiO 2The adsorbed catalyst can be recycled under the action of a magnetic field, which reduces costs and greatly enhances practical application capabilities.

[0034] 1.3 BET Analysis: The specific surface area of ​​a material is one of the important characteristics to measure its adsorption capacity. The specific surface area and pore volume of the prepared material were measured by the BET method.

[0035] Magnetic DBC / SiO 2 and MnFe 2 O 4 / DBC / SiO 2 N 2 The adsorption-desorption isotherms are shown in Figure 3 . It can be seen that the silicon-modified biochar DBC / SiO 2 and magnetic MnFe 2 O 4 / DBC / SiO 2 The adsorption isotherms of DBC / SiO2 are all type IV isotherms. It is also found that there is a H3 type hysteresis loop in the relative pressure range of 0.5-1.0, which indicates that DBC / SiO2 2 and magnetic MnFe 2 O 4 / DBC / SiO 2 The pore structure is complex. 2 Compared with MnFe 2 O 4 / DBC / SiO 2 The pore volume of the material decreased significantly, which is because in MnFe 2 O 4 / DBC / SiO 2 The pores are loaded with MnFe 2 O 4 Nanoparticles occupy a portion of the pore volume.

[0036] 1.4 XRD analysis: XRD characterization can be used to analyze the crystal structure of the material. In order to further understand the structure and crystallinity of the prepared magnetic composite material, MnFe 2 O 4 、DBC / SiO 2 and MnFe 2 O 4 / DBC / SiO 2 The material is scanned at a speed of 2° / min in the range of 10 to 70°. Figure 4 As shown in Figure 2, there are obvious diffraction peaks at 2θ = 20.8°, 26.6°, 29.6°, 34.9°, 42.4°, 52.6°, 56.1° and 61.5°, which are consistent with the SiO2 The (100) and (011) crystal planes and MnFe in the standard card (JCPDS NO. 79-1906) 2 O 4 The (220), (311), (400), (422), (511) and (440) crystal planes in the standard card (JCPDS 10-0319) match each other. In addition, it can be observed that the MnFe 2 O 4 Post-magnetic MnFe 2 O 4 / DBC / SiO 2 The material appeared with MnFe 2 O 4 This further demonstrates the successful synthesis of magnetic MnFe 2 O 4 / DBC / SiO 2 Composite materials.

[0037] 1.5 SEM+EDS+mapping analysis: In order to further improve the magnetic MnFe 2 O 4 / DBC / SiO 2 The morphology, structure and distribution of the composite material were characterized by scanning SEM+EDS+mapping. Figure 5 In (ab), magnetic MnFe can be observed 2 O 4 / DBC / SiO 2 The microstructure is nearly spherical and uniform in size. It can be clearly seen that fine particles are distributed on the surface of the biochar material, which can be inferred to be MnFe 2 O 4 Nanoparticles were successfully attached to silicon-modified biochar DBC / SiO 2 The pores of DBC / SiO 2 MnFe in surface pore size 2 O 4 This is consistent with the results of the above BET characterization and confirms that the MnFe 2 O 4 It will occupy the pores on the surface of the biochar material, resulting in magnetic MnFe 2 O 4 / DBC / SiO 2 The specific surface area decreases. In addition, magnetic MnFe 2 O 4 / DBC / SiO 2 The corresponding element energy spectrum is as follows Figure 5As shown in (c), the peaks of the constituent elements such as C, O, Si, Fe and Mn can be clearly observed. As shown in Table 1, the C and O elements are 20.83% and 58.22%, respectively, which is attributed to the oxygen element in the modified biochar and each component material. In addition, through element mapping Figure 5 It can be seen from (dg) that each element is evenly distributed in the magnetic MnFe 2 O 4 / DBC / SiO 2 Composite material, it can be seen that the prepared magnetic MnFe 2 O 4 / DBC / SiO 2 The preparation of the composite material was consistent with the assumption.

[0038] Table 1 Magnetic properties of MnFe 2 O 4 / DBC / SiO 2 Elemental composition and proportion of catalyst

[0039] 2. MnFe 2 O 4 / DBC / SiO 2 Analysis of Cu(Ⅱ) and TC removal 2.1 Effect of Cu(Ⅱ) on TC degradation: In order to explore the effect of Cu(Ⅱ) on the removal of TC, different concentrations of Cu(Ⅱ) and TC were mixed as simulated wastewater (Cu(Ⅱ) = 0, 10, 20, 30, 50 mg / L, TC = 20 mg / L), and the PMS catalytic degradation experiment was carried out after adsorption. Figure 6 As shown, in a single TC system, magnetic MnFe 2 O 4 / DBC / SiO 2 The removal rate of TC after adsorption was 22%, and as the concentration of Cu(Ⅱ) increased to 10, 20, 30, and 50 mg / L, the removal rates of TC were 16%, 13%, 9%, and 4%, respectively. It can be seen that Cu(Ⅱ) significantly inhibited the adsorption process of TC. This may be because: when a large amount of Cu(Ⅱ) and TC exist in the solution at the same time, the magnetic MnFe 2 O 4 / DBC / SiO 2 When the dosage is constant, competitive adsorption will occur between Cu(Ⅱ) and TC, competing for the adsorption sites on the surface of the composite material; at the same time, there is also the possibility that Cu(Ⅱ) and TC will form a complex under acidic conditions, resulting in a decrease in the rate of adsorption and diffusion, forming blockage, thereby reducing the adsorption effect.

[0040] After adsorption for two hours to reach equilibrium, PMS was added for catalytic degradation reaction. It can be observed that after two hours of reaction, the degradation efficiency of the single TC system reached 90%, while the efficiency of the composite system with different concentrations of Cu(Ⅱ) was improved after adsorption equilibrium and then adding PMS, which increased to 93.1%, 95.3%, 96.8% and 99.4% at 10, 20, 30 and 50 mg / L, respectively. Compared with the single system, the degradation effect of TC by adsorbed and fixed Cu(Ⅱ) was significantly improved. Cu(Ⅱ) promoted the degradation efficiency of tetracycline and accelerated the reaction rate, which may be because: Cu(Ⅱ) was adsorbed to the surface of the adsorption catalyst, and after the oxidant PMS was added, it participated in the catalytic reaction process, produced more active oxygen species, and oxidized and degraded TC. As the concentration of Cu(Ⅱ) increased, the degradation efficiency of TC adsorbed on MnFe 2 O 4 / DBC / SiO 2 The more Cu(Ⅱ) on the surface, the more it participates in the catalytic oxidation reaction, so the degradation effect is better. Therefore, Cu(Ⅱ) in the composite system will inhibit the adsorption of TC and promote the degradation of TC.

[0041] 2.2 Effect of TC on Cu adsorption: In order to study the effect of TC on magnetic MnFe 2 O 4 / DBC / SiO 2 The effect of adsorption of Cu(Ⅱ) was studied by using different concentrations of TC and a certain amount of Cu(Ⅱ) to prepare polluted wastewater. The relationship curve between the adsorption amount of Cu(Ⅱ) qe (mg / g) and time t (min) at different times was taken as the research object, and a relationship curve was drawn. Figure 7 It can be seen that compared with the adsorption of Cu(Ⅱ) in a single system, the presence of tetracycline in the composite system (TC=0, 10, 20, 30, 50 mg / L, Cu(Ⅱ)=20 mg / L) increased the equilibrium adsorption of Cu(Ⅱ), and the adsorption amount increased with the continuous increase of tetracycline concentration. 2 O 4 / DBC / SiO 2 The maximum adsorption capacity of Cu(Ⅱ) is 48.61 mg / g. When the TC concentration is 10 mg / L, the maximum adsorption capacity of Cu(Ⅱ) increases to 58.33 mg / g. When the TC concentration is increased to 50 mg / L, the maximum adsorption capacity of Cu(Ⅱ) can reach 73.80 mg / g.

[0042] As the concentration of tetracycline increases, a large amount of Cu(II) reacts with TC to form a complex, and the Cu(II) in the solution exists in the form of a complex, which reduces the surface charge and enhances the electrostatic attraction with the adsorbent surface, thereby greatly improving the magnetic MnFe 2 O4 / DBC / SiO 2 The adsorption rate and equilibrium adsorption amount of copper by the composite material; at the same time, for a copper solution with a certain initial concentration, the presence of tetracycline and biochar can appear in the form of "magnetic MnFe 2 O 4 / DBC / SiO 2 The bridging effect of the tetracycline-copper form increased the maximum adsorption of copper by bridging with tetracycline.

[0043] 3. Analysis of adsorption catalysis mechanism 3.1 EPR test and quenching experiment: In order to study the 2 O 4 / DBC / SiO 2 The main active oxygen species of TC degradation by the / PMS system were quenched by the corresponding quenchers EtOH, TBA, BQ and FFA, respectively. 、·OH、 and 1 O 2 The results are as follows Figure 8 As shown in Figure 2, the introduction of the quencher inhibits TC degradation to varying degrees. Figure 8 In (a), the addition of EtOH to MnFe 2 O 4 / DBC / SiO 2 The degradation of TC in the / PMS system was significantly inhibited, and the degradation efficiency dropped to 59.32%. When TBA and p-BQ were introduced, TC was slightly inhibited, and the degradation efficiencies were 78.04% and 80.33%, respectively. Obviously, the inhibitory effect of EtOH was greater than that of TBA and p-BQ, which indicated that in the MnFe 2 O 4 / DBC / SiO 2 In the / PMS system, the main free radicals are hydroxyl radicals, sulfate radicals and superoxide radicals, among which sulfate radicals play a leading role in the reaction. 1 O 2 When FFA was added, the degradation efficiency of TC decreased by 36.98% to 62.93%, which indicates that 1 O 2 There is also important participation.

[0044] In order to further determine the MnFe 2 O 4 / DBC / SiO 2 We used DMPO and TEMP as spin traps to capture the reactive oxygen species that may be generated in the / PMS system. 、·OH、 and 1 O 2 EPR analysis was performed. Figure 8 As shown in (b)-(c), DMPO- , DMPO-·OH and DMPO- signal, and it increases with the reaction time, which indicates that CZO / MnFe 2 O 4 / The PMS system generates , OH and .at the same time, Figure 8 In (d), there appears 1 O 2 The triple EPR spectrum (1:1:1) corresponding to oxidized TEMP means 1 O 2 These results are consistent with the quenching experiment results. In summary, the quenching experiment and EPR prove that 、·OH、 and 1 O 2 existence, and and 1 O 2 It plays a major role in the entire degradation process.

[0045] 3.2 XPS analysis: In order to further analyze its potential adsorption catalytic mechanism, XPS characterization analysis was performed on the materials before and after the catalytic reaction. The results are as follows Fig. 9 As shown, MnFe 2 O 4 / DBC / SiO 2 The main elements are C, O, Mn, Fe and Si. At binding energies of 61.08 eV, 283.18 eV, 644.36 eV and 712.80 eV, Si 2p, C 1s, O 1s, Mn 2p and Fe 2p all have relatively obvious peaks. After the adsorption reaction, a peak representing Cu 2p appears at a binding energy of 1072.08 eV. This means that MnFe 2 O 4 / DBC / SiO 2 The successful adsorption of Cu(Ⅱ). In addition, the peak intensities of Si 2p, C 1s, O 1s, Mn 2p and Fe 2p corresponding to the full spectrum after adsorption were reduced and shifted, indicating that oxygen-containing functional groups participated in the reaction with Si, Mn and Fe. From the C 1s spectrum ( Fig. 9In (b), the peaks at 282.88 eV, 284.88 eV, and 287.68 eV correspond to the functional groups C−C, C−O, and O−C=O, respectively. However, compared with those before adsorption, the binding energies and peak areas corresponding to the three functional groups after the reaction have changed, indicating that the functional groups containing hydroxyl and carboxyl groups play an important role in adsorption. Fig. 9 In (c), the peaks at 529.48 eV, 531.68 eV, and 532.88 eV correspond to C=O, M-O (metal oxygen bond: Mn-O and Fe-O), and Si-O, respectively. In the O 1s spectrum of the adsorbed material, the position and area of ​​the peaks corresponding to the oxygen-containing functional groups have changed to a certain extent. It can be seen that the area of ​​the metal oxygen bond has increased after the reaction, which may be due to the adsorption process of Cu(Ⅱ). In addition, the peak areas of the Fe 2p and Mn 2p spectra before and after the reaction have changed, which indirectly confirms that both Fe and Mn are involved in the reaction. Finally, as shown in Fig. 9 As shown in (g), after adsorption, a peak corresponding to Cu 2p appeared at a binding energy of 934.68, and after the catalytic reaction, the peak area of ​​Cu 2p changed, indicating that the adsorbed Cu(Ⅱ) participated in the catalytic degradation reaction.

[0046] In this embodiment, MnFe 2 O 4 / DBC / SiO 2 Numerous oxygen-containing functional groups on the surface participate in the adsorption enrichment process, including carboxyl, carbonyl, hydroxyl, and metal oxygen bonds. 2 O 4 / DBC / SiO 2 The main adsorption mechanisms of Cu(Ⅱ) include pore filling, surface complexation of oxygen-containing functional groups, electrostatic attraction, and MnFe 2 O 4 / DBC / SiO 2 The catalytic degradation of TC is mainly caused by the adsorbed Cu(Ⅱ) and magnetic MnFe2O4 participating in the catalytic generation of PMS. and 1 O 2 , which plays a major role in the entire degradation process.

[0047] 4. Cyclic regeneration performance analysis: In order to test the prepared magnetic MnFe 2 O 4 / DBC / SiO 2The regeneration performance of the composite material was studied. In this experiment, the material was desorbed and washed with 0.1 mol / L NaOH solution and pure water respectively until no Cu(Ⅱ) and TC were detected in the washing liquid. After magnetic separation, the material was dried and then cycled. This experiment analyzed the magnetic MnFe 2 O 4 / DBC / SiO 2 Recycling performance of raw composite materials.

[0048] The experiment was repeated five times, and the results were as follows Fig.10 After 5 cycles, MnFe 2 O 4 / DBC / SiO 2 The removal rates of Cu(Ⅱ) and TC were 73.53% and 90.21% respectively. 2 O 4 / DBC / SiO 2 It still maintains relatively stable adsorption catalytic performance, which is of great significance for its practical application in treating complex pollution in wastewater.

[0049] In this example, magnetic MnFe 2 O 4 / DBC / SiO 2 Materials. MnFe 2 O 4 / DBC / SiO 2 The structural morphology of the material was analyzed and it was found that the composite material has both magnetic properties and MnFe 2 O 4 and biochar materials DBC / SiO 2 The catalytic and adsorption properties of the catalyst were investigated, and its treatment effect on the binary composite pollution of Cu(Ⅱ) and TC and its recycling performance were also investigated. The conclusions are as follows: The experimental results show that MnFe 2 O 4 / DBC / SiO 2 The removal effect of Cu(Ⅱ) and TC is significantly affected by the concentration of Cu(Ⅱ) and TC in the solution. When the concentration of Cu(Ⅱ) is constant, increasing the concentration of TC will increase the adsorption rate of Cu(Ⅱ) and greatly improve the removal effect of Cu(Ⅱ). However, when the concentration of TC is 20 mg / L, increasing the concentration of Cu(Ⅱ) to 50 mg / L will reduce the adsorption rate of MnFe 2 O 4 / DBC / SiO 2 The adsorption effect of TC was up to 15.74%, and after adding PMS, the adsorption on MnFe2 O 4 / DBC / SiO 2 The Cu on the surface will participate in the catalytic reaction of PMS, produce more active oxygen free radicals, and significantly improve the TC degradation effect. When the Cu(Ⅱ) concentration is 50 mg / L, the TC degradation effect reaches 99.8%.

[0050] The characterization results show that MnFe 2 O 4 / DBC / SiO 2 The specific surface area is 24.89 m2 / g, and the pores of the material are mesoporous. This is because the magnetic MnFe 2 O 4 After that, the pores of the material are filled with MnFe 2 O 4 However, the XRD results showed that MnFe2O4 and SiO 2 The characteristic peaks of MnFe 2 O 4 and SiO 2 It indicates that it is successfully loaded on the DBC surface. In addition, the XPS full spectrum after adsorption shows obvious Cu 2p peaks, which indicates that Cu is effectively adsorbed. According to the results of EPR and quenching experiments, a large number of active oxygen free radicals are generated in the catalytic reaction after adsorption. and 1 O 2 It plays a major role in the entire degradation process.

[0051] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a magnetic composite material, characterized in that: The preparation method comprises: Weigh 500 mg of silicon-modified biochar material, distribute it completely in 40 mL of ethylene glycol solution after ultrasonication, then add 0.0005 mol of MnCl2•4H2O and 0.001 mol of FeCl3•6H2O, stir until completely dissolved, add 3.4 g of sodium acetate trihydrate and 1 g of polyethylene glycol 2000, and continue stirring for the first preset time to obtain a preliminary sample; The preliminary sample is heated to react at a first preset temperature, and solid-liquid separation is performed under an external magnetic field condition, and the magnetic composite material is obtained after washing with ethanol and clean water and drying.

2. The method for preparing the magnetic composite material according to claim 1, characterized in that: The ultrasonic time of the silicon-modified biochar material is 3 hours, the first preset time is 60 minutes, the first preset temperature is 200° C., and the heating reaction time of the preliminary sample is 12 hours.

3. The method for preparing the magnetic composite material according to claim 1, characterized in that: The silicon-modified biochar material is SiO2 / DBC, and its preparation method comprises: 10 g of natural montmorillonite is weighed and added into 250 mL of deionized water to form a montmorillonite suspension, and after ultrasonicating the montmorillonite suspension, 20 g of rice husk powder passed through a 40-mesh sieve is immersed in the suspension, and the solid is separated after magnetic stirring, and dried at a second preset temperature to obtain a preliminary solid; The preliminary solid is placed in a high-temperature muffle furnace filled with nitrogen and heated to a third preset temperature at a preset heating rate for pyrolysis, and then washed with deionized water and dried to obtain a silicon-modified biochar material.

4. The method for preparing the magnetic composite material according to claim 3, characterized in that: The ultrasonic time of the montmorillonite suspension is 0.5 h, the magnetic stirring time is 2 h, and the second preset temperature is 50° C. to 70° C.

5. The method for preparing the magnetic composite material according to claim 3, characterized in that: The preset heating rate is a constant 10°C / min, the third preset temperature is 500°C, and the pyrolysis time is 2h.

6. A magnetic composite material, characterized in that: The magnetic composite material is prepared by the method for preparing the magnetic composite material according to any one of claims 1 to 5.

7. Use of the magnetic composite material as claimed in claim 6 in degrading copper and tetracycline pollutants in wastewater.

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