Preparation method of FeNi alloy biochar for removing organic pollutants

Abstract

The invention belongs to the technical field of water treatment, and discloses a preparation method of FeNi alloy biochar for removing organic pollutants, NiFe2O4 is loaded on biochar through pyrolysis by adopting ball milling-pyrolysis combination, and a catalyst of biochar loaded FeNi alloy nanoparticles is obtained. The preparation method disclosed by the invention is simple and environment-friendly, and the uniformly dispersed carbon FeNi alloy nanoparticles are effectively loaded. The modified biochar has an extremely high specific surface area and an excellent adsorption function, and can effectively remove organic pollutants in water. According to the prepared catalyst, the biomass carbon substrate material and NiFe2O4 are used for improving the microscopic performance of the carbon surface, the adsorption rate and the adsorption capacity are effectively improved, the PH use range is wide, the material regeneration utilization rate is increased, and good use value and application prospects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology and relates to a method for preparing FeNi alloy biochar for removing organic pollutants. Background Technology

[0002] With the rapid development of industries such as agriculture, medicine, and plastics, a large amount of organic wastewater containing pesticides, antibiotics, and endocrine disruptors has entered water bodies.

[0003] These pollutants are characterized by high toxicity, difficulty in degradation, and easy bioaccumulation, and may even pose a health risk.

[0004] To mitigate the harm of organic pollutants in the aquatic environment, people have been exploring various remediation strategies, including traditional adsorption methods, advanced oxidation processes, photolysis, and biodegradation.

[0005] Among these methods, adsorption stands out as a particularly attractive approach due to its simplicity, economy, high efficiency, and non-toxicity.

[0006] Recent studies have used modified biochar, granular activated carbon, and metal-organic frameworks as adsorbent materials. Biochar is inexpensive and readily available, and its high specific surface area makes it suitable for adsorption.

[0007] Alloying modification has promising applications in many areas, such as hydrogen evolution reaction, oxidative dehydrogenation reaction, and microwave absorption. To date, only a few studies have applied alloy-modified carbon materials to wastewater treatment.

[0008] Recent research has confirmed that cobalt-iron alloys coated with carbon layers can achieve in-situ activation of sodium hypophosphite through a synergistic effect of restricted adsorption and surface activation, and can efficiently mineralize organic pollutants.

[0009] Research reports that using an iron-nickel alloy electrode combined with a photocatalytic decomposition strategy can effectively degrade trimethoprim.

[0010] A catalytic membrane design utilizing nitrogen-doped carbon nanotubes encapsulated in a magnetic nickel-cobalt alloy is proposed for the degradation of emerging pollutants.

[0011] Although the catalytic performance of alloy@biochar in Fenton-like reactions (such as cobalt-iron alloys, nickel-cobalt alloys, and iron-nickel alloys) has been reported, its mechanism of action on organic wastewater in the absence of external oxidants remains unclear.

[0012] Biochar itself is an ideal carrier matrix, possessing high dispersibility, high porosity, and good electron transport capabilities. Composite biochar materials can effectively control the leaching and aggregation of metal ions. To date, there are no known methods or applications for preparing FeNi alloy biochar for water treatment adsorption. Summary of the Invention

[0013] The purpose of this invention is to provide a method for preparing FeNi alloy biochar for removing organic pollutants, based on existing technology. This method is low-cost, efficient, and environmentally friendly.

[0014] Technical solution: A FeNi alloy biochar for removing organic pollutants: The FeNi alloy biochar composition includes biomass carbon-based substrate material and metal oxides.

[0015] The technical solution further defined in this invention is as follows: the raw material of the biomass carbon-based substrate material is lignin biochar or other carbon source biomass materials; the metal oxide includes nano-NiFe2O4.

[0016] Preferably, the other carbon source biomass materials include loofah-based biochar or rice straw biochar.

[0017] This invention also protects a method for preparing FeNi alloy biochar for removing organic pollutants, comprising the following steps: (1) Take the crushed biomass into a tube furnace and pyrolyze it at 700°C for 120 min under N2 atmosphere. The heating rate is 5°C / min. After cooling to room temperature, take it out and crush it again through a 100-mesh sieve to obtain the original biochar (LVC700) and prepare the precursor of biomass carbon-based material. (2) The biomass carbon-based material precursor obtained in step (1) is calcined at 400-700°C for 2-6 hours under nitrogen to obtain biomass carbon-based material; (3) Add excess 0.1 mol / L dilute hydrochloric acid to the biomass carbon-based material obtained in step (2), shake at 25°C and 200 rpm for 12 h, filter and separate, wash the solid biochar obtained after separation with ultrapure water and dry it in an oven. (4) Take 3.0g of fully washed biochar after acidification and mix it with 0.6g of nano nickel ferrite in a ball mill at 1600rpm and mix thoroughly. (5) The solid mixture obtained in step (4) is placed in a tube furnace for pyrolysis, with a gradient temperature increase of 5°C / min, and kept sealed for 2 hours after reaching 700°C; the resulting product is the FeNi alloy composite biochar adsorbent; Beneficial effects: Compared with the prior art, the present invention has the following advantages: 1) The biomass carbon-based material precursor used in this invention has the advantages of low preparation cost and easy availability. After modification, it can significantly improve the adsorption performance of the catalyst and also has the advantages of wide pH adaptability, resistance to anion interference and easy regeneration.

[0018] 2) Combined with adsorption and dispersion on the surface of carbon materials, it improves the uniformity of metal ion dispersion on the material surface. Attached Figure Description

[0019] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0020] Figure 1 This is the X-ray diffraction pattern of the adsorbent in Example 1.

[0021] Figure 2 This is the X-ray diffraction pattern of the adsorbent in Example 2.

[0022] Figure 3 This is an electron microscope image of the material obtained in Example 1.

[0023] Figure 4 It is the X-ray absorption fine structure spectrum (EXAFS) of iron and nickel.

[0024] Figure 5 The specific surface area and pore distribution of the adsorbent in Example 1 are shown.

[0025] Figure 6 This is the infrared spectrum of the adsorbent in Example 1.

[0026] Figure 7 These are Raman spectra of the adsorbent FeNi before and after the reaction.

[0027] Figure 8 These are graphs showing the effects of different adsorbents on removing imidacloprid from water.

[0028] Figure 9 This is the adsorption isotherm of FeNi-LVC at 25℃.

[0029] Figure 10 This represents the adsorption capacity of FeNi-LC at different pH values ​​and imidacloprid concentrations.

[0030] Figure 11 These are the pseudo-first-order and pseudo-second-order adsorption kinetic curves for FeNi-LVC and FeNi-LC.

[0031] Figure 12 The effect of different anions (5mM) on the adsorption effect of imidacloprid (CO=100ppm) is investigated.

[0032] Figure 13This is a test of the adsorption capacity of FeNi-LC adsorbent material for different pollutants.

[0033] Figure 14 This is the XRD pattern of FeNi-LC after PH adsorption exposure.

[0034] Figure 15 It is the hysteresis loop of FeNi alloy biochar (FeNi-LC). Implementation

[0035] In the following embodiments, neonicotinoid pesticide wastewater (imidacloprid) was selected as a typical recalcitrant organic wastewater for simulation experiments. Imidacloprid is not a limitation on organic pollutants; any pollutant falling within the scope of organic pollutants is within the protection scope of this invention. The invention is further illustrated below with specific embodiments.

[0036] Example 1

[0037] A method for preparing FeNi alloy biochar for removing organic pollutants includes the following steps: The raw biomass was placed in a tube furnace and heated under nitrogen (…). Pyrolysis was carried out at 700°C for 120 minutes at a heating rate of 5°C / min under an atmospheric atmosphere. This yielded loofah vine-based biochar (LVC-700), lignin-based biochar (LC-700), and straw-based biochar (SC-700). Subsequently, 3.0 g of acid-washed WBC-S700 was mixed with 0.6 g of nano-nickel ferrite (NiF). The samples were mixed in a ball mill at 1600 rpm to ensure thorough mixing. Then, the ball-milled samples underwent a second pyrolysis process in a tube furnace, and the final products were named FeNi-LVC700, FeNi-LC700, and FeNi-SC700, respectively.

[0038] Example 2

[0039] A method for preparing a FeNi alloy biochar catalyst for removing persistent organic pollutants includes the following steps: The raw biomass was placed in a tubular furnace (Anhui Beiyike Equipment Technology Co., Ltd., China) and heated under nitrogen ( Pyrolysis was carried out for 120 minutes at different pyrolysis temperatures (300, 400, 700°C) at a heating rate of 5°C / min under an atmospheric atmosphere. This yielded loofah vine-based biochar (LVC-300, LVC-400, LVC-700). Subsequently, 3.0 g of acid-washed LVC was mixed with 0.6 g of nano-nickel ferrite (NiF). The samples were mixed in a ball mill at 1600 rpm to ensure thorough mixing. Then, the ball-milled samples underwent a second pyrolysis process in a tube furnace, and the final products were named FeNi-LVC300, FeNi-LVC400, and FeNi-LVC700, respectively. Different mass ratios of NiFe2O4 / biochar are indicated by numbers in parentheses. Furthermore, FeNi-LVC300, FeNi-LVC400, and FeNi-LVC700 were prepared via a second pyrolysis process by controlling the pyrolysis temperature to be consistent with the first pyrolysis temperature (300°C, 400°C, or 700°C).

[0040] Figure 1 The X-ray diffraction pattern of the adsorbent is shown in Figure 1. The XRD results of the iron-nickel modified biochar show diffraction angles of 43.9 degrees and 51.2 degrees, which are consistent with the (111) and (200) crystal planes in PDF#12-0736, indicating that NiFe2O4 is converted into an iron-nickel alloy through carbothermal reduction (Figure 1). At the same time, it also contains (220), (311), and (440) crystal planes corresponding to NiFe2O4, or magnetite-Fe2O3 (PDF#79-0419).

[0041] Figure 2 The X-ray diffraction pattern of the adsorbent in Example 2 shows that during pyrolysis at high temperatures of 300 or 400°C, the NiFe2O4 component did not undergo a significant phase transformation, while the formation of the iron-nickel alloy phase required a higher carbon reduction temperature (700°C).

[0042] Figure 3 These are electron micrographs of the material. SEM shows that the FeNi biochar composite exhibits a distinct layered structure on its surface, covered with pointed crystals. Figure 3 a, 3b). SEM shows that the layered structure of FeNi-LC has more loose porosity characteristics ( Figure 3 c, 3d). Furthermore, the morphological changes of the modified biochar were successfully observed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), confirming that carbon (C), iron (Fe), and nickel (Ni) were uniformly distributed on the surface of the modified biochar. Figure 3 e). The surface of the modified biochar contains elements such as carbon (C), iron (Fe), and nickel (Ni), with mass proportions of 84.50%, 10.22%, and 5.22%, respectively, indicating that iron and nickel have been successfully incorporated into the modified biochar.

[0043] Figure 4X-ray absorption fine structure spectroscopy (EXAFS) analysis of iron and zinc. Fe K-edge XANES spectra of FeNi-LC show that Fe mainly exhibits a peak at approximately 2.33 Å, primarily attributed to the presence of Fe foil (Figure 4b). WT-EXAFS macroscopically confirmed the presence of Fe foil and Fe₂O₃. Ni K-edge XANES spectra of FeNi-LC show a major peak at approximately 2.2 Å, mainly attributed to the presence of Ni foil. WT-EXAFS also macroscopically confirmed the presence of Ni foil. The EXFAS results and XRD analysis corroborate each other, indicating the presence of FeNi alloys, Fe-O, and Ni-O bonds in the modified biochar.

[0044] Figure 5 The specific surface area and pore size distribution of the catalyst in Example 1 are shown. BET results indicate that the type of biochar has a significant impact on adsorption performance. Among these biochar materials, lignin has the highest initial BET value, with a yield surface area of ​​595.1216 m². 2 g⁻¹ (FeNi-LC). The differences in BET between different adsorbents can be attributed to the different precursors used. The BET surface area of ​​FeNi-LVC-700 is 239.2370 m². 2 g -1, higher than FeNi-LVC-300 (32.0934 m 2 g -1), FeNi-LVC-400 (14.9899 m 2 g -1).

[0045] Figure 6 This is the infrared spectrum of the adsorbent in Example 1. FTIR results show that FeNi-LVC300 and FeNi-LVC400, with pyrolysis temperatures of 300°C and 400°C respectively, exhibit an absorption peak with -COOH. However, no -COOH was detected in the alloy materials produced at pyrolysis temperature of 700°C, whether FeNi-LVC700, FeNi-LC700, or FeNi-SC700. This indicates that the alloyed carbon material masks the spectral peak signal.

[0046] Example 3

[0047] The effects of different types of catalysts (FeNi-SC700, FeNi-LVC700, FeNi-LC700) prepared in Example 1 of this invention on the adsorption of imidacloprid (IMI) in water were tested.

[0048] The experiment was conducted by adding 0.20 g / L of adsorbent to 50 mL of a 10.0 mg / L imidacloprid (IMI) solution (initial pH = 6.8). The solution was stirred in the dark for 30.0 min to reach adsorption and desorption equilibrium. Samples were taken at different time intervals (5, 10, 15, 30, 60 min), filtered through a 0.22 μm membrane into brown autosampler vials, and then analyzed by high-performance liquid chromatography (HPLC) to determine the concentration.

[0049] Figure 7 Raman spectroscopy before and after adsorption. The two characteristic peaks at 1348 cm⁻¹ and 1591 cm⁻¹ belong to the D band (defect structure) of sp₃ and the G band (graphite structure) of sp₂, respectively. An I_D / I_G ratio > 1 indicates that the material may have a higher degree of defect and stable graphitization.

[0050] Figure 8 The adsorption effects of different adsorbents on imidacloprid in water were shown. When the dosage was 0.2 g / L, FeNi-LVC and FeNi-LC achieved an adsorption effect of >99.0% on imidacloprid, while FeNi-SC had a removal rate of only 0.2% after 1 hour of adsorption. This indicates that the FeNi alloyed modified biochar is related to the original biomass type, and that loofah-based and lignin-based adsorbents performed better in adsorbing 10 ppm imidacloprid wastewater.

[0051] Figure 9 This is the adsorption isotherm of FeNi-LVC at 25℃. The results show that the adsorption capacity of FeNi-LVC is (Langmuir Q0 = 15.4162 mg / g) and the kinetic rate (K0) is... L 1.2631 mg / g min).

[0052] Example 3

[0053] The adsorbent FeNi-LC prepared in Example 1 of this invention was tested to adsorb imidacloprid (IMI) in water at different pH values.

[0054] Figure 10 The results showed that the FeNi-LC adsorbent exhibited excellent adsorption capacity (200-240 mg / g) in a pH range of 3 to 11 (CO = 100 mg / L). The lowest adsorption capacity was observed at pH = 11, while the highest was observed at pH = 3. Adsorption tests using the alloy-biochar model demonstrated its applicability over a wide range of solution pH.

[0055] Example 4

[0056] The adsorption kinetics of the adsorbents FeNi-LVC and FeNi-LC prepared in Example 1 of this invention were fitted.

[0057] Figure 11 According to the fitting coefficient (R) 2 For FeNi-LC, the pseudo-second-order fit R0 2 The value (0.9991) is higher than the R-value of the pseudo-first-order model. 2 The value was 0.9749 (see Table 2). This indicates that the pseudo-second-order kinetics more accurately reflects the IMI adsorption kinetics. The adsorption process is the result of both physical and chemical adsorption. Using the pseudo-second-order kinetic model, the Qe value for FeNi-LC was calculated to be 230.46 ± 0.63 mg / g, and the Qe value for FeNi-LVC was 15.2145 mg / g. These results demonstrate the significant advantages of using lignin-based biochar as a precursor.

[0058] Example 5

[0059] The effect of the FeNi-LC catalyst prepared in Example 1 of this invention on adsorbing imidacloprid IMI (100 ppm) in water under the influence of different 5 mM anions was tested.

[0060] Figure 12 The results show that a slight Qe response occurs in the presence of chloride, hydrogen phosphate, and bicarbonate ions, and this response is most significant in the first 15 minutes of the test. However, when adsorption reaches equilibrium, the difference in Qe of the adsorbent under the influence of different ions is not significant.

[0061] Example 6

[0062] The adsorption effect of the FeNi-LC catalyst prepared in Example 1 of this invention on different pollutants (imidacloprid IMI, phenol (PhOH), bisphenol A (BPA), p-nitrophenol (PNP)) in water was tested (CO=100ppm).

[0063] Figure 13 The results show that IMI has the strongest adsorption capacity, followed by PNP, PhOH, and BPA. This indicates that the developed material exhibits selective adsorption, with the strongest adsorption for nitro-functionalized groups.

[0064] Figure 14 The FeNi-LC adsorbent recovered in Example 3 under different pH tolerance experiments showed that the XRD structure of the alloy catalyst remained intact regardless of the initial pH conditions of 3-11, indicating good structural stability and reusability.

[0065] Figure 15The hysteresis loop test of FeNi-LC showed that FeNi-LC, as an alloy-modified biochar, possesses a high saturation magnetization of 24.6 emu / g and a coercivity of 124.9 Oe. It also exhibits detectable remanence and a closed hysteresis loop, indicating that the material can be magnetically recycled and reused.

[0066] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to the embodiments, and the general principles of this description can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing FeNi alloy biochar for removing organic pollutants, wherein the FeNi alloy biochar uses a variety of biochars as a carrier, characterized in that: Includes the following steps: (1) Take the crushed biomass into a tube furnace and pyrolyze it at 700°C for 120 min under N2 atmosphere. The heating rate is 5°C / min. After cooling to room temperature, take it out and crush it again through a 100-mesh sieve to obtain the original biochar (LVC700) and prepare the precursor of biomass carbon-based material. (2) The biomass carbon-based material precursor obtained in step (1) is calcined at 400-700°C for 2-6 hours under atmospheric conditions to obtain biomass carbon-based material. (3) Add excess 0.1 mol / L dilute hydrochloric acid to the biomass carbon-based material obtained in step (2), shake it in a constant temperature shaker at 25°C and 200 rpm for 12 h, and then filter it. The separated solid biochar is washed with ultrapure water and then dried in an oven. (4) Take 3.0g of acidified and washed LVC700 and mix it with 0.6g of nano nickel ferrite in a ball mill at 1600rpm. (5) Then take out the ball milled sample and perform secondary pyrolysis carbonization in a tube furnace (the pyrolysis temperature and time are the same as in step 1), and name it FeNi-LVC700.

2. The method for preparing FeNi alloy biochar for removing organic pollutants according to claim 1, characterized in that: FeNi alloy biochar has an amorphous graphitic carbon structure with (111) and (200) crystal planes of NiFe alloy and (220), (311) and (440) crystal planes of NiFe2O4, as well as a (002) crystal plane.

3. The method for preparing FeNi alloy biochar for removing organic pollutants according to claim 2, characterized in that: The biomass derived from agricultural waste includes any one of the following: loofah-based biomass, dealkalized lignin, and rice structural biomass.

4. The method for preparing FeNi alloy biochar for removing organic pollutants according to claim 1, characterized in that: Biomass carbon-based material precursors are calcined at 400-700°C for 2-6 hours under nitrogen atmosphere to obtain biomass carbon-based materials.

5. The method for preparing FeNi alloy biochar for removing organic pollutants according to claim 1, characterized in that: In step (2), the atmosphere is nitrogen.

6. The method for preparing FeNi alloy biochar for removing organic pollutants according to claim 1, characterized in that: In step (1), the gradient heating rate is 5°C per minute, and when the temperature reaches 700°C, it is maintained at a constant temperature for 2 hours.

7. The method for preparing FeNi alloy biochar for removing organic pollutants according to claim 1, characterized in that: The biomass carbon-based material was mixed with an excess of 0.1 mol / L dilute hydrochloric acid and shaken in a constant temperature shaker at 25°C and 200 rpm for 12 h, followed by vacuum filtration separation.

8. The method for preparing FeNi alloy biochar for removing organic pollutants according to claim 1, characterized in that: In step (4), the acidified and washed LVC700 is mixed with 0.6g of nano nickel ferrite in a ball mill for physical homogenization.

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