A waste mask modified biochar, a preparation method thereof and application thereof in removal of heavy metals

Abstract

The present application belongs to the technical field of waste recycling, and particularly relates to a waste mask modified biochar, a preparation method thereof and application thereof in removal of heavy metals. The waste mask, carbide slag and / or lime are mixed to obtain a mixture, and the mixture is carbonized to obtain the waste mask modified biochar. The preparation method provided by the present application is simple and easy to implement, and does not cause harm to the environment and human health. Meanwhile, the waste mask modified biochar obtained by the preparation method provided by the present application has good removal effect on heavy metal ions in water, such as Cd(II) and As(III). Thus, the preparation method provided by the present application helps to improve the resource utilization rate of waste masks while reducing the environmental pollution risk of waste masks, meets the requirement of sustainable development, and has great application potential in the field of heavy metal ion removal.

Description

Technical Field

[0001] This invention belongs to the field of waste recycling technology, specifically relating to a modified biochar from discarded masks, its preparation method, and its application in removing heavy metals. Background Technology

[0002] According to the World Health Organization, the global daily consumption of masks currently reaches billions, with nearly 300 tons of discarded masks generated daily. The consumption and use of disposable masks will remain at a high level for a considerable period. If not properly handled, discarded disposable masks will pose potential environmental hazards. For example, they may carry viruses, posing a threat to public health; plastic fragments from mask decomposition accumulate through the food chain, affecting the ecological balance of land and sea, ultimately posing a potential threat to human health; and the large-scale disposal of disposable masks also wastes resources, contradicting the goals of sustainable development. Therefore, measures should be taken to ensure their harmless treatment or recycling.

[0003] Currently, existing manufacturers extract and fuse fibers from discarded masks to produce environmentally friendly materials, or use discarded disposable masks to create new filter materials or print 3D face shields. However, because disposable masks contain multiple materials, recycling them is more difficult than recycling other types of waste. Traditional methods for disposing of disposable masks have drawbacks or stringent requirements; for example, incineration may cause air pollution; landfill may pollute the soil; and disinfecting, decomposing, and reusing masks requires specialized recycling facilities and conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a modified biochar from waste masks, its preparation method, and its application in the removal of heavy metals. The preparation method provided by this invention realizes the harmless treatment and resource utilization of waste masks. The modified biochar from waste masks has a significant effect on the removal of heavy metal Cd(II) ions and As(III) ions in water bodies, and has great application potential in the treatment of heavy metal pollution in water bodies.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing modified biochar from waste face masks, comprising the following steps:

[0007] Waste masks are mixed with a modifier to obtain a mixture; the modifier includes carbide slag and / or lime;

[0008] The mixture is carbonized to obtain the modified biochar from the waste masks.

[0009] Preferably, the mass ratio of the discarded mask to the modifier is (1-3):(1-3).

[0010] Preferably, the carbonization temperature is ≥400℃ and the time is ≥1h; the heating rate from room temperature to the carbonization temperature is ≥10℃ / min; the carbonization is carried out in a flowing protective gas atmosphere, and the flow rate of the protective gas is ≥100mL / min.

[0011] This invention provides modified biochar from waste masks prepared by the preparation method described in the above technical solution.

[0012] This invention provides the application of modified biochar from waste masks, as described in the above technical solution, in the removal of heavy metals.

[0013] Preferably, the application is for removing heavy metal ions from water.

[0014] Preferably, the application includes the following steps:

[0015] Adding the modified biochar from discarded masks described in the above technical solution to water bodies polluted with heavy metals allows for the adsorption and removal of heavy metal ions in the water.

[0016] Preferably, the heavy metal ions include divalent cadmium ions and / or trivalent arsenic ions;

[0017] The concentration of divalent cadmium ions in the heavy metal-polluted water bodies was 50–300 mg·L⁻¹. -1 The mass concentration of trivalent arsenic ions is 0.05–50 mg·L⁻¹. -1 .

[0018] Preferably, the pH value of the heavy metal polluted water body is 4 to 7;

[0019] The mass ratio of the modified biochar from the discarded masks to the volume of the water polluted by heavy metals is (0.001-0.01) g: 20 mL.

[0020] Preferably, the adsorption removal temperature is 20–25°C, and the adsorption removal is carried out under oscillation conditions at a speed of 200–220 r / min. -1 The time ranges from 1 to 720 minutes.

[0021] This invention provides a method for preparing modified biochar from discarded face masks, comprising the following steps: mixing discarded face masks and a modifier to obtain a mixture; the modifier includes carbide slag and / or lime; and carbonizing the mixture to obtain the modified biochar from the discarded face masks. To avoid potential harm to the environment and human health while utilizing discarded face masks as resources, this invention provides a method for preparing modified biochar from discarded face masks using discarded face masks as raw materials, combined with a modifier, and subjected to co-pyrolysis carbonization under high-temperature conditions. The preparation method provided by this invention is simple and easy to implement, and will not cause harm to the environment or human health. Furthermore, the modified biochar from discarded face masks obtained by the preparation method provided by this invention has a good removal effect on heavy metal ions, such as Cd(II) and As(III), in water. Therefore, the preparation method provided by this invention helps to improve the resource utilization rate of discarded face masks while reducing the environmental pollution risk, meeting the requirements of sustainable development, and the obtained modified biochar from discarded face masks has great application potential in the field of heavy metal ion removal. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of the carbide slag modified mask carbon K3D1 obtained in Example 1 of the present invention;

[0023] Figure 2 This is a scanning electron microscope image of the carbide slag modified mask carbon K1D3 obtained in Example 1 of the present invention;

[0024] Figure 3 The energy spectrum of the carbide slag modified mask carbon K1D1 obtained in Example 8 of this invention before and after co-adsorption of Cd(II) and As(III) is shown. Detailed Implementation

[0025] This invention provides a method for preparing modified biochar from waste face masks, comprising the following steps:

[0026] Waste masks are mixed with a modifier to obtain a mixture; the modifier includes carbide slag and / or lime;

[0027] The mixture is carbonized to obtain the modified biochar from the waste masks.

[0028] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0029] This invention mixes discarded face masks with a modifier to obtain a mixture; the modifier includes carbide slag and / or lime. In this invention, the modifier preferably includes carbide slag and / or lime, more preferably carbide slag. In this invention, the discarded face mask is preferably a discarded disposable face mask. This invention preferably involves cutting the discarded face mask into small pieces before mixing. In this invention, before mixing, the invention preferably further includes drying the discarded face mask and the modifier. The drying temperature is preferably 60°C. The drying is preferably carried out in an oven. The mass ratio of the discarded face mask to the modifier is preferably (1-3):(1-3), specifically preferably 1:1, 1:3, 3:1, 2:1, or 1:2.

[0030] After obtaining the mixture, the present invention carbonizes the mixture to obtain the modified biochar from the waste mask. In the present invention, the carbonization method is preferably an oxygen-limited temperature-controlled carbonization method. The carbonization is preferably carried out in a tubular furnace, and the present invention preferably loads the mixture into the furnace tube of the tubular furnace for carbonization. The carbonization temperature is preferably ≥400℃, more preferably 400~500℃, and even more preferably 400℃. The carbonization holding time is preferably ≥1h, more preferably 1~2h, and even more preferably 1h. The heating rate from room temperature to the carbonization temperature is preferably ≥10℃ / min, more preferably 10~15℃ / min, and even more preferably 10℃ / min. In the present invention, the carbonization is preferably carried out in a flowing protective gas atmosphere, and the protective gas is preferably nitrogen. The flow rate of the protective gas is preferably ≥100mL / min, more preferably 100~150mL / min, and even more preferably 100mL / min. This invention utilizes high-purity nitrogen as the carrier gas at a flow rate of 100 mL / min to create an oxygen-deficient environment within the entire carbonization chamber. In this invention, during the carbonization process, the waste mask and the modifier undergo co-pyrolysis carbonization to obtain modified biochar from the waste mask.

[0031] In this invention, after the carbonization process yields the modified biochar from the waste mask, the modified biochar from the waste mask is preferably cooled to room temperature and then stored in a desiccator.

[0032] This invention provides modified biochar from waste masks prepared by the preparation method described in the above technical solution.

[0033] This invention provides the application of modified biochar from waste masks, as described in the above technical solution, in the removal of heavy metals.

[0034] In this invention, the preferred application is the removal of heavy metal ions from water.

[0035] In this invention, the application preferably includes the following steps:

[0036] Adding the modified biochar from discarded masks described in the above technical solution to water bodies polluted with heavy metals allows for the adsorption and removal of heavy metal ions in the water.

[0037] In this invention, the modified biochar from discarded masks is preferably sieved through a 100-mesh sieve. Before adding the modified biochar from discarded masks described in the above technical solution to the water body polluted by heavy metals, this invention preferably grinds and sieves the modified biochar from discarded masks sequentially. This invention does not have special requirements for the specific implementation process of the grinding. The sieve used for sieving is preferably 100-mesh. In this invention, the pH value of the water body polluted by heavy metals is preferably 4-7, specifically preferably 4, 4.5, 5, 5.5, 6, 6.5, or 7. The heavy metal ions in the water body polluted by heavy metals preferably include divalent cadmium ions and / or trivalent arsenic ions. In a specific embodiment of this invention, the water body polluted by heavy metals is specifically preferably polluted by divalent cadmium ions or polluted by trivalent arsenic ions. The mass concentration of divalent cadmium ions in the water body polluted by heavy metals is preferably 50-300 mg·L⁻¹. -1 Specifically, 50 mg·L is preferred. -1 100 mg·L -1 150 mg·L -1 200 mg·L -1 250 mg·L -1 Or 300 mg·L -1 The preferred mass concentration of trivalent arsenic ions in the heavy metal-polluted water is 0.05–50 mg·L⁻¹. -1 Specifically, 1 mg·L -1 1.5 mg·L -1 0.05 mg·L -1 0.1 mg·L -1 0.2 mg·L -1 0.4 mg·L -1 0.8 mg·L -1 0.6 mg·L -1 2 mg·L -1 4 mg·L -1 8 mg·L -1 20 mg·L -1 Or 50 mg·L -1 .

[0038] In this invention, the mass ratio of the modified biochar from waste masks to the volume of water polluted by heavy metals described in the above technical solution is (0.001-0.01) g: 20 mL, specifically preferably 0.001 g: 20 mL, 0.002 g: 20 mL, 0.004 g: 20 mL, 0.005 g: 20 mL, 0.006 g: 20 mL, 0.008 g: 20 mL, or 0.01 g: 20 mL.

[0039] In this invention, the adsorption removal temperature is preferably 20–25°C, and the adsorption removal is preferably carried out under oscillation conditions, with the oscillation speed preferably being 200–220 r / min. -1 The preferred time is 1 to 720 min, more preferably 1 min, 2 min, 5 min, 10 min, 30 min, 60 min, 120 min, 240 min, 360 min or 720 min.

[0040] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0041] Example 1

[0042] First, shredded disposable masks, carbide slag, and lime were placed in an oven and dried at 60℃. Modified biochar was prepared using an oxygen-limited temperature-controlled carbonization method. Appropriate amounts of disposable masks (K) and carbide slag (D) were weighed at mass ratios of 1:0, 3:1, 1:1, 1:3, and 0:1, respectively. Simultaneously, disposable masks (K) and lime (L) were weighed at a mass ratio of 1:1. The specific carbonization process was as follows: After uniformly mixing the disposable masks and carbide slag, and the disposable masks and lime, the mixture was placed into the furnace tube of a vacuum tube furnace. The maximum carbonization temperature was set to 400℃, the heating rate was 10℃ / min, and the carbonization time was 1 hour under the set maximum temperature conditions. After natural cooling to room temperature, the mixture was removed and stored in a desiccator for later use.

[0043] Biochar (carbide slag modified mask char) prepared from a mixture of disposable waste masks and carbide slag was designated as K1D0, K3D1, K1D1, K1D3, and K0D1 respectively at mass ratios of 1:0, 3:1, 1:1, 1:3, and 0:1. Biochar (lime modified mask char) prepared from disposable waste masks and lime at a mass ratio of 1:1 was designated as K1L1. All prepared biochars were ground and sieved through a 100-mesh sieve and used for characterizing and analyzing the physicochemical properties of modified mask char, as well as for adsorption experiments of heavy metal ions such as Cd(II) and As(III) in water.

[0044] Biochar yield: Weigh the dry weight of the prepared materials before and after pyrolysis, and calculate the yield of different biochars. The calculation formula is as follows: Yield (%) = Dry weight of sample after pyrolysis / Dry weight of mixed raw material sample × 100.

[0045] Determination of pH value of modified mask biochar: The biochar was extracted with deionized water at a ratio of 1:10 (m / V), and the solution was shaken horizontally for 1 hour at a shaking rate of 200 rpm. The pH value of the solution was measured using a pH electrode.

[0046] As shown in Table 1, the biochar from disposable waste masks prepared in Example 1 is weakly alkaline. Furthermore, with the increase in the mixing ratio of carbide slag and disposable waste masks, the pH of the carbide slag-modified mask biochar is higher, exhibiting strong alkalinity. Compared to biochar prepared by mixing with lime, the pH value of the carbide slag-modified mask biochar prepared in the same proportion is slightly higher, and with the increase in the proportion of carbide slag added, the pH value of the modified biochar is significantly higher than that of K1L1.

[0047] Table 1. Basic properties of biochar prepared from disposable waste masks and calcium carbide slag at different mixing ratios.

[0048] Yield (%) 4.26 29.04 54.17 77.28 99.5 53.75 pH 7.42 11.42 12.23 12.40 12.48 12.05

[0049] Taking K3D1 and K1D3 as examples, such as Figure 1 and Figure 2 As shown, comparing electron microscopy images of modified mask carbon prepared from disposable waste masks and calcium carbide slag in two different proportions, it can be observed that the microporous structure and morphology of the mask carbon prepared by K3D1 and K1D3 are different. The mask carbon modified with a lower proportion of calcium carbide slag has a smaller microporous structure and a relatively larger pore volume and specific surface area.

[0050] Example 2

[0051] To verify the removal efficiency of different proportions of calcium carbide slag-modified biochar on Cd(II) ions in water, this example used an initial Cd(II) solution concentration of 250 mg / L. -1 The solution had a pH of 5.5. Using 0.01M NaNO3 solution as the electrolyte, it was added to 50mL centrifuge tubes at two solid-liquid ratios: 0.001g:20mL and 0.005g:20mL, respectively. The solutions were incubated at 220rpm at 25℃. -1 After shaking for 12 hours and filtering through a 0.45 μm filter membrane, the Cd(II) content in the blank and test solutions was determined by inductively coupled plasma mass spectrometry. The test results are shown in Table 2.

[0052] Table 2. Removal rate (%) of Cd(II) from solution by different carbide slag modified biochar

[0053] 0.001g:20mL 0 15.65％ 17.53％ 16.42％ 12.77％ 0.005g:20mL 0 62.43％ 66.36％ 70.56％ 15.14％

[0054] Table 2 shows that biochar prepared from disposable masks had no adsorption effect on Cd(II) in water. Biochar modified with carbide slag significantly improved its removal rate of Cd(II) from water, exceeding that of lime-modified biochar at the same ratio. Furthermore, the removal rate of Cd(II) from water increased significantly with the increase of the adsorbate in the modified biochar. Considering both the heavy metal adsorption effect and practical application requirements, modifying the biochar with carbide slag resulted in better heavy metal adsorption.

[0055] Example 3

[0056] Taking the carbide slag modified mask carbon K1D1 as an example, this study investigated the adsorption effect of carbide slag modified biomass on heavy metals Cd(II) and As(III) in water bodies with different pH values ​​under different initial solution pH conditions.

[0057] The adsorbent material used was K1D1, with initial solution concentrations of Cd(II) and As(III) of 250 mg / L and 1.0 mg / L, respectively. -1 The initial pH gradients of Cd(II) and As(III) solutions were set to 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, and 7.0. 0.01M NaNO3 solution was used as the electrolyte, and added to 50mL centrifuge tubes at a solid-liquid ratio of 0.006g:20mL. The solutions were incubated at 220rpm at 25℃. -1 After shaking for 12 hours, the solution was filtered through a 0.45 μm filter membrane, and the contents of Cd(II) and As(III) in the blank and diluted solutions were determined by inductively coupled plasma mass spectrometry.

[0058] Based on the measurement results of removal rate and heavy metal content, calculations and analyses were performed to obtain some representative data, as shown in Table 3.

[0059] Table 3. Removal rates (%) of Cd(II) and As(III) from water by K1D1 at different initial solution pH levels.

[0060] Cd(II) 77.09 81.8 83.46 86.81 89.73 91.55 93.31 As(III) 32.48 33.39 33.21 36.09 35.42 33.8 32.46

[0061] Table 3 clearly shows that the initial pH of the solution affected the adsorption efficiency of modified mask charcoal K1D1 for Cd(II) and As(III). For Cd(II) alone, as the solution pH increased from 4.0 to 7.0, the removal rate of Cd(II) by K1D1 increased from 77.09% to 93.31%. However, for the removal rate of As(III) alone, the removal rate increased from the solution pH from 4.0 to 5.5, and then decreased, meaning that the removal rate of As(III) by K1D1 reached its highest level when the solution pH was 5.5.

[0062] Example 4

[0063] Taking modified biochar K1D1 for face masks as an example, the adsorption effect of modified biochar dosage on Cd(II) and As(III) in water was studied. Modified biochar K1D1 with masses of 0.001, 0.002, 0.004, 0.006, 0.008, or 0.01 g were weighed into 50 mL centrifuge tubes, and then 20 mL of a solution with an ion concentration of 250 mg / L was added. -1 Cd(II) or 1.5 mg L -1 As(III), the electrolyte solution is 0.01M NaNO3, the initial pH of the solution is 5.5, and the reaction is carried out at 25℃ for 200 rpm. -1 After shaking for 12 hours, the solution was filtered through a 0.45 μm filter membrane, and the contents of Cd(II) and As(III) in the blank and diluted solutions were determined by inductively coupled plasma mass spectrometry.

[0064] Based on the measurement results of removal rate and heavy metal content, calculations and analyses were performed to obtain some representative data, as shown in Table 4.

[0065] Table 4. Removal rates (%) of Cd(II) and As(III) in water by different K1D1 concentrations

[0066] Cd(II) 25.88 44.82 62.78 86.78 94.63 98.74 As(III) 19.68 23.61 29.42 36.1 38.13 40.88

[0067] As shown in Table 4, the increase in the concentration of the adsorbent-modified mask carbon K1D1 significantly increased the removal rate of Cd(II) and As(III) in the water, and the adsorption effect of K1D1 on Cd(II) was higher than that on As(III).

[0068] Example 5

[0069] Taking modified biochar K1D1 for face masks as an example, the adsorption kinetics of modified biochar for Cd(II) and As(III) in water were studied. In this example, the initial solution concentrations of Cd(II) and As(III) were 250 mg / L and 1.0 mg / L, respectively. -1 The solution pH was 5.5. Using 0.01M NaNO3 solution as the electrolyte, it was added to 50mL centrifuge tubes at a solid-liquid ratio of 0.006g:20mL, and centrifuged at 220rpm at 25℃. -1 The mixture was shaken for 1 min, 2 min, 5 min, 10 min, 30 min, 60 min, 120 min, 240 min, 360 min and 720 min. After the experiment, the filtrate was filtered through a 0.45 μm filter membrane and the contents of Cd(II) and As(III) in the blank and diluted solutions were determined by inductively coupled plasma mass spectrometry.

[0070] Based on the measurement results of removal rate and heavy metal content, calculations and analyses were performed to obtain some representative data, as shown in Table 5.

[0071] Table 5. Removal rates (%) of Cd(II) and As(III) in water by K1D1 at different shaking times.

[0072] Cd(II) 7.23 10.69 17.21 22.01 35.4 43.79 58.01 69.1 79.21 82.85 As(III) 1.7 5.32 11.55 20.71 30.03 50.47 80.69 83.14 71.02 56.67

[0073] As can be clearly seen from Table 5, the removal rate of Cd(II) by carbide slag modified biochar K1D1 gradually increases with the extension of shaking time; while for the removal rate of As(III) alone, the shaking time shows an upward trend from 1 to 240 min, and then a downward trend, that is, the removal rate of As(III) by K1D1 reaches the highest when the shaking time is 240 min.

[0074] Example 6

[0075] Taking modified biochar K1D1 for face masks as an example, the isothermal adsorption effect of modified biochar on Cd(II) and As(III) in water was studied. In this example, the initial concentrations of Cd(II) in the solution were 50, 100, 150, 200, 250, and 300 mg·L⁻¹. -1 In this embodiment, the initial As(III) solution concentrations were 0.05, 0.10, 0.20, 0.40, 0.80, and 1.0 mg·L⁻¹. -1 The solution had a pH of 5.5. Using 0.01M NaNO3 solution as the electrolyte, it was added to 50mL centrifuge tubes at a solid-liquid ratio of 0.006g:20mL, and centrifuged at 220rpm at 25℃. -1 The mixture was shaken for 12 hours. After the experiment, the filtrate was filtered through a 0.45 μm filter membrane. The contents of Cd(II) and As(III) in the blank and diluted solutions were determined by inductively coupled plasma mass spectrometry.

[0076] Based on the measurement results of removal rate and heavy metal content, calculations and analyses were performed to obtain some representative data, as shown in Table 6.

[0077] Table 6. Removal rate (%) of K1D1 for different Cd(II) and As(III) ion concentrations in water.

[0078] Cd(II) 97.75 97.17 97.89 97.19 86.37 63.08 concentration 0.05 0.10 0.20 0.40 0.80 1.00 As(III) 93.85 85.87 75.49 68.53 56.11 42.48

[0079] As can be clearly seen from Table 6, with the increase of ion concentration in the solution, the basic effect of carbide slag modified biochar K1D1 on Cd(II) and As(III) shows a decreasing trend.

[0080] Example 7

[0081] Taking modified biochar K1D1 for face masks as an example, this study investigated the adsorption effect of modified biochar on As(III) under different concentrations of Cd(II). In this example, the initial Cd(II) solution concentrations were 50, 100, 150, 200, 250, and 300 mg / L. -1 In this embodiment, the initial concentration of As(III) solution is 1.0 mg / L. -1 The solution pH was 5.5. Using 0.01M NaNO3 solution as the electrolyte, it was added to 50mL centrifuge tubes at a solid-liquid ratio of 0.006g:20mL, and centrifuged at 220rpm at 25℃. -1 The mixture was shaken for 12 hours. After the experiment, the filtrate was filtered through a 0.45 μm filter membrane. The contents of Cd(II) and As(III) in the blank and diluted solutions were determined by inductively coupled plasma mass spectrometry.

[0082] Based on the measurement results of removal rate and heavy metal content, calculations and analyses were performed to obtain some representative data, as shown in Table 7.

[0083] Table 7. Removal rate (%) of As(III) from water by K1D1 in the presence of different Cd(II) ions

[0084] Cd(II) 99.85 99.86 99.87 99.76 86.77 73.22 As(III) 95.73 99.34 99.52 99.40 99.45 99.40

[0085] As can be clearly seen from Table 7, as the concentration of Cd(II) ions in the solution increases from 50 to 150 mg / L... -1 The modified biochar K1D1 made from carbide slag promoted the removal rate of As(III) in water, and then the effect stabilized.

[0086] Example 8

[0087] Taking modified biochar K1D1 for face masks as an example, this study investigated the adsorption effect of modified biochar on As(III) under different concentrations of Cd(II). In this example, the initial concentration of Cd(II) in the solution was 250 mg / L. -1 In this embodiment, the initial As(III) solution concentrations were 0.2, 0.4, 0.6, 1.0, 2, 4, 8, 20, and 50 mg / L. -1 The solution pH was 5.5. Using 0.01M NaNO3 solution as the electrolyte, it was added to 50mL centrifuge tubes at a solid-liquid ratio of 0.006g:20mL, and centrifuged at 220rpm at 25℃. -1 The mixture was shaken for 12 hours. After the experiment, the filtrate was filtered through a 0.45 μm filter membrane. The contents of Cd(II) and As(III) in the blank and diluted solutions were determined by inductively coupled plasma mass spectrometry.

[0088] Based on the measurement results of removal rate and heavy metal content, calculations and analyses were performed to obtain some representative data, as shown in Table 8.

[0089] Table 8. Removal rate (%) of Cd(II) from water by K1D1 in the presence of different As(III) ions

[0090] Cd(II) 83.80 89.29 84.78 81.24 84.01 85.95 86.35 89.30 87.13 As(III) 98.19 98.83 99.42 99.27 99.51 99.52 99.66 99.64 99.49

[0091] Table 8 clearly shows that the adsorption effect of carbide slag-modified mask carbon on heavy metals in Cd(II) and As(III) composite water bodies is significantly better than that of single adsorption. When the Cd(II) ion concentration in the solution is fixed, with the increase of As(III) concentration, the removal rate of Cd(II) by K1D1 material is approximately 81.24%–89.30%, and the removal rate of As(III) can reach approximately 98.19%–99.62%. Compared with the results of single adsorption, the adsorption effect on As(III) is significantly enhanced. Figure 3 The energy dispersive spectroscopy (EDS) spectrum shows that the modified charcoal mask can effectively adsorb Cd(II) and As(III) on its surface. This may be because the modified charcoal mask undergoes precipitation or complexation reactions during the adsorption of Cd(II)-As(III) complex ions, thereby effectively reducing the concentration of heavy metals in the solution.

[0092] As shown in the above embodiments, this invention provides a method for preparing modified biochar from waste masks by using waste masks as raw materials, compounding them with modifiers, and co-pyrolyzing and carbonizing them under high-temperature conditions. The preparation method provided by this invention is simple and easy to implement, and will not cause harm to the environment or human health. Furthermore, the modified biochar from waste masks obtained by the method provided by this invention has a good removal effect on heavy metal ions, such as Cd(II) and As(III), in water. Therefore, the preparation method provided by this invention helps to improve the resource utilization rate of waste masks while reducing the environmental pollution risk of waste masks, which meets the requirements of sustainable development. The modified biochar from waste masks obtained has great application potential in the field of heavy metal ion removal.

[0093] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An application of modified biochar from discarded face masks in removing heavy metal ions from water, characterized in that, The heavy metal ions include divalent cadmium ions and trivalent arsenic ions; in the water polluted by heavy metals, the mass concentration of divalent cadmium ions is 50~250 mg·L⁻¹. -1 The mass concentration of trivalent arsenic ions is 0.05~50 mg·L⁻¹. -1 The mass ratio of the modified biochar from the waste masks to the volume of the water polluted by heavy metals is (0.005~0.01) g: 20 mL; the preparation method of the modified biochar from the waste masks includes the following steps: Waste masks and a modifier are mixed to obtain a mixture; the modifier is carbide slag; the mass ratio of the waste masks to the modifier is (1~3):(1~3). The mixture is carbonized to obtain the modified biochar from the waste mask. The carbonization temperature is 400~500℃ and the holding time is 1~2h.

2. The application according to claim 1, characterized in that, The heating rate from room temperature to the carbonization temperature is ≥10℃ / min; the carbonization is carried out in a flowing protective gas atmosphere, the flow rate of which is ≥100 mL / min.

3. The application according to claim 1, characterized in that, The application includes the following steps: Adding modified biochar from discarded masks to water bodies polluted with heavy metals allows for the adsorption and removal of heavy metal ions.

4. The application according to claim 1 or 3, characterized in that, The pH value of the heavy metal-polluted water body is 4-7.

5. The application according to claim 3, characterized in that, The adsorption removal is carried out at a temperature of 20-25°C under oscillation conditions at a speed of 200-220 r·min. -1 The time ranges from 1 to 720 minutes.

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