Preparation method and application of composite modified charcoal filler

Abstract

The invention discloses a preparation method and application of a composite modified biochar filler. The preparation method comprises the following steps: S1, pyrolysis treatment; S2, modification treatment; S3, secondary calcination; the application refers to application in a heavy metal-antibiotic synergistic removal system. The biochar filler prepared by combining three-stage temperature control pyrolysis with an NH3 activation modification process has the characteristics of large specific surface area, high mechanical strength and excellent magnetic separation performance, and can realize effective removal of heavy metal-antibiotic combined pollution.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for preparing and applying a composite modified biochar packing material. Background Technology

[0002] With the rapid development of industry and livestock farming, the treatment of wastewater contaminated with heavy metals and antibiotics has become a major challenge in the water treatment field. my country's "GB18918-2002 Discharge Standard of Pollutants for Urban Wastewater Treatment Plants" and local standards in Beijing (such as DB11 / 307-2013) clearly stipulate that the emission limit for copper ions is ≤0.3 mg / L (Class A standard). The "List of Key Controlled New Pollutants" released by the Ministry of Ecology and Environment in 2023 included sulfonamide antibiotics in the limit control for the first time, specifying an emission limit of ≤0.1 mg / L. Under these strict control requirements, the treatment of this type of wastewater faces a dual technical bottleneck: firstly, Cu... 2+ There is a fundamental conflict between the adsorption removal and the reaction mechanism of antibiotic oxidative degradation. Secondly, high concentrations of Cl- (20-50 g / L) in aquaculture wastewater can poison catalytic active sites and interfere with material recovery, leading to a significant decrease in the stability of the treatment system.

[0003] Current modified biochar technology has systemic limitations: regarding the defect of single function, the magnetic rice husk biochar of patent CN105797693A has limitations in its ability to modify Pb. 2+ / Cd 2+ The adsorption capacity reaches 85 mg / g, but the specific surface area is only 110 m². 2 The biochar, with its low concentration of phosphate and lack of catalytically active sites, cannot degrade antibiotics. While the phosphoric acid-activated biochar in patent CN110327882A increases Zn / Cd adsorption rate by 20%, its compressive strength is only 4-6 MPa, and the breakage rate reaches 18% after two weeks of fixed-bed operation. The lack of synergistic treatment capability is evident in the fact that while Fenton oxidation can degrade sulfamethoxazole (half-life t1 / 2 ≈ 15 min, literature DOI: 10.1016 / j.watres.2022.118952), Cu... 2+ At concentrations >10 mg / L, the oxidant is ineffectively consumed by more than 30% due to the catalytic reaction. In engineering applications, traditional biochar has a particle size <100 μm and a bulk density of 0.2-0.5 g / cm³. 3 Under high-salt conditions, the magnetic recovery rate is <80%; although ceramic modification (patent CN116351395B) increases the compressive strength to ≥8MPa, the specific surface area is ≤150m². 2 / g, Cu 2+ The adsorption capacity is only 58.7 mg / g; magnetic nitrogen doping (patent CN114917943B) enhances catalytic activity (sulfonamide t1 / 2≈12 min), but the mechanical strength is only 3-5 MPa and the fluidized bed breakage rate is >25%.

[0004] The above technical defects reveal the core contradiction: a single modification method is difficult to meet the four-dimensional performance requirements simultaneously. ① Cu 2+ adsorption capacity ≥ 120 mg / g (100% higher than ceramic modification); ② sulfonamide degradation half-life t1 / 2≤8 min (87.5% higher than Fenton oxidation efficiency); ③ compressive strength ≥ 8 MPa (fluidized bed breakage rate < 5%); ④ high salt (Cl- = 50 g / L), magnetic recovery rate ≥ 97% (0.5T magnetic field). In the prior art, the contradictions between adsorption and catalytic activity, mechanical strength and specific surface area, high salt stability and recovery efficiency have not been broken through, and it is urgent to develop a composite biochar filler with multiple functions and an intelligent synergistic system to solve the technical barriers of heavy metal-antibiotic separation. SUMMARY

[0005] The purpose of the present application is to overcome the problems of low treatment efficiency, insufficient material performance, complex process and difficulty in adapting to wastewater with specific concentration range in the prior art for treating heavy metal-antibiotic composite contaminated wastewater, and to provide a composite modified biochar filler and a preparation method and application thereof.

[0006] The technical solution of the present application is: a preparation method of a composite modified biochar filler, comprising the following steps:

[0007] S1, pyrolysis treatment

[0008] First, the agricultural and forestry waste and clay components are mixed in a weight ratio of 2:1, molded under a pressure of 10-15 MPa, then heated to 350-420℃ at a rate of 5-10℃ / min under nitrogen protection and kept for 6-24h, then heated to 550-600℃ at a rate of 10-15℃ / min and kept for 6-24h, and finally heated to 700-780℃ at a rate of 15-20℃ / min, when the temperature reaches 700℃, NH3 is introduced at a flow rate of 0.5-1.5 L / min and kept for 10-48h;

[0009] S2, modification treatment

[0010] The pyrolysis product is immersed in a modification liquid containing Fe 3+ compound, and then the pH of the modification liquid is adjusted to 9.5-10.5 by a pH adjuster, and electroless deposition is carried out at 45-55℃ for 20-40min;

[0011] S3, secondary calcination

[0012] The deposited product is mixed with 5-10wt% carboxymethyl cellulose to form granules with a particle size of 2-5mm, and then secondary calcination is carried out at 600-800℃ for 1-3h under nitrogen protection to obtain the composite modified biochar filler.

[0013] Description: The filler prepared by the above method has a specific surface area of ≥300 m 2 / g, a compressive strength of ≥8 MPa, an XRD pattern simultaneously showing a graphite carbon (002) crystal face (2θ = 26.5° ± 0.5°), a Fe3O4 characteristic peak (2θ = 35.5° ± 0.5°), and a kaolinite (001) crystal face (2θ = 12.5° ± 0.5°), a saturation magnetization of ≥20 emu / g, and pyridine nitrogen accounting for ≥40% in surface nitrogen species through XPS full spectrum analysis; can simultaneously and efficiently adsorb heavy metal ions (Cu 2+ with an adsorption capacity of ≥120 mg / g) and catalytically degrade antibiotics (sulfonamide degradation half-life ≤8 min), achieving synergistic removal of pollutants.

[0014] Further, in S1, the agricultural and forestry waste is a mixture of corn stalks and sawdust in a mass ratio of 2-4:1, which is then crushed to a particle size of 50-100 μm; the clay component is a mixture of kaolin and montmorillonite in a mass ratio of 7:3;

[0015] Description: Sawdust is rich in lignin, which mainly improves the pore structure and mechanical strength and enhances the hydrophobic antibiotic adsorption function; the ratio of corn stalks to sawdust can effectively balance the porosity and strength, and is suitable for a dynamic adsorption tower; the ratio of kaolin to montmorillonite can take into account the structural stability and catalytic activity, thereby improving the utilization rate of persulfate.

[0016] Further, in S2, the modification liquid is composed of 15-20 wt% of iron sulfate and 2-6 wt% of polyethyleneimine with a molecular weight of 800-1000 Da in a mass ratio of 2.5-10:1;

[0017] Description: The advantages of using ferric ions as the modification liquid are that the formation of hydroxy ferric oxide precipitate under alkaline conditions can simultaneously adsorb heavy metals and antibiotics, and that the phenomenon of molten iron is reduced by avoiding the ineffective consumption of persulfate by ferrous ions; the use of iron sulfate and polyethyleneimine as the modification liquid can take advantage of the properties of polyethyleneimine to stabilize Fe 3+ colloid, enhance antibiotic adsorption, and optimize pore structure. 3+ Further, polyethyleneimine increases the service life of the filler.

[0018] Further, in S2, the pH regulator is a sodium hydroxide solution with a mass concentration of 5-8 wt% or an ammonia water with a mass concentration of 10-15 wt%;

[0019] Description: The use of the above regulator can effectively adjust the pH to promote the electroless deposition of Fe 3+ and avoid premature precipitation.

[0020] In another aspect, the application also provides a composite modified biochar filler and an application method thereof.

[0021] The heavy metal-antibiotic synergistic removal system comprises an upflow adsorption tower filled with the composite modified biochar filler, a fluidized bed reactor connected in series with the upflow adsorption tower, a persulfate dosing device arranged in the fluidized bed reactor, and a magnetic separation device arranged at the end of the system. 2+ The electrode double control is started when ORP>200mV or Cu 2+ ≤1mg / L.

[0022] The volume ratio of the upflow adsorption tower to the fluidized bed reactor is 1:0.5-1.5, the empty bed contact time of the upflow adsorption tower is 10-45min, the dosing amount of the persulfate is 0.5-3g / L, and the magnetic field strength of the magnetic separation device is 0.5-0.8T.

[0023] The composite modified biochar filler is used in the heavy metal-antibiotic synergistic removal system. 2+ The catalytic oxidation step is intelligently triggered by the double signals of ORP and Cu

[0024] Further, the filling rate of the composite modified biochar filler is ≥70-90%.

[0025] The composite filler has the best effect under the above filling conditions.

[0026] Further, the application method is as follows:

[0027] Step 1: detecting whether the wastewater contains tetracycline antibiotics, the concentration of copper ions, and the concentration of sulfonamide antibiotics.

[0028] Step 2: when the wastewater contains tetracycline antibiotics and the concentration of copper ions is <10mg / L and the concentration of sulfonamide antibiotics is <5mg / L, the wastewater is treated by the following method:

[0029] (1) the wastewater is introduced into the upflow adsorption tower, and the empty bed contact time is controlled to be 10-15min;

[0030] (2) the effluent indicators are monitored in real time, and when the concentration of Cu 2+ in the effluent of the upflow adsorption tower is ≤1mg / L or ORP>200mV, the effluent is immediately introduced into the fluidized bed reactor;

[0031] (3) 0.5-1g / L of persulfate and 0.05-0.1g / L of Fe 2+ are added into the fluidized bed reactor to start the oxidation catalytic reaction.

[0032] (4) Finally, the magnetic separation device with magnetic field strength of 0.5-0.8T is processed for 1-5min, and the processing is completed;

[0033] When the wastewater contains tetracycline antibiotics and the copper ion concentration is 10-100mg / L, and the sulfonamide antibiotic concentration is 5-50mg / L, adjust the empty bed contact time in (1) to 15-30min; at the same time, add 1-2g / L persulfate and 0.1-0.3g / L Fe 2+ to the fluidized bed reactor in (3) to start the oxidation catalytic reaction; the rest of the steps remain unchanged;

[0034] When the wastewater contains tetracycline antibiotics and the copper ion concentration is >100mg / L, and the sulfonamide antibiotic concentration is >50mg / L, adjust the empty bed contact time in (1) to 30-45min; at the same time, add 2-3g / L persulfate and 0.3-0.5g / L Fe 2+ to the fluidized bed reactor in (3) to start the oxidation catalytic reaction; the rest of the steps remain unchanged.

[0035] When the wastewater does not contain tetracycline antibiotics but contains sulfonamides, the dosing ratio of persulfate to Fe 2+ remains unchanged, and the oxidation reaction can be achieved by the synergistic catalysis of Fe3O 4 / on the surface of the filler and pyridine nitrogen;

[0036] When the wastewater contains tetracycline antibiotics, but the Cu 2+ concentration and the sulfonamide antibiotic concentration fall into different ranges, the combination is executed: the empty bed contact time is selected according to the Cu 2+ concentration; the dosing amount of persulfate and Fe 2+ is selected according to the sulfonamide antibiotic concentration; the oxidation triggering step is selected according to the ORP / Cu 2+ threshold value of the corresponding scheme in the adsorption step; the separation and detection step is executed according to the discharge index of the corresponding scheme in the oxidation step;

[0037] Explanation: According to the concentration characteristics of heavy metals and antibiotics in wastewater, a hierarchical treatment scheme is adopted, the catalytic oxidation step is intelligently triggered by the dual signals of ORP and Cu 2+ concentration, the system runs stably and reliably, and has significant technical advantages and application prospects in industrial and aquaculture wastewater treatment.

[0038] Further, the magnetic separation device end also has a filler regeneration module, after treatment, the composite modified biochar filler is taken out, 0.1-0.5 mol / L HCl solution is added to the composite modified biochar filler according to the solid-liquid ratio of 5 mL:1 g, under the condition of 22-25 DEG C temperature and 120-150 rpm oscillation speed, oscillation is carried out for 25-30 min, then 0.1 mol / L NaOH solution and 10% volume concentration ethanol are added, under the condition of 45-50 DEG C temperature, 35-40 kHz ultrasonic frequency and 90-100 W ultrasonic power, treatment is carried out for 15-20 min, finally, the composite modified biochar filler is immersed in FeCl3 and CoCl2 solution with a total concentration of 0.1 mol / L, under the condition of pH=9.5 and 50-55 DEG C temperature, electroless deposition is carried out for 25-30 min, and the regenerated composite modified biochar filler is obtained.

[0039] Description: After long-term operation of the biochar filler in the heavy metal-antibiotic cooperative removal system, the following problems may be faced, adsorption saturation, Cu 2+ , tetracycline and other pollutants occupy active sites (such as oxygen-containing functional groups, Fe 3+ loading sites); pore blockage, organic pollutants (such as sulfonamides) degradation intermediates block micropores; magnetic component loss, CoFe2O4 partially dissolves in acidic or high-salt environment; the above methods can elute heavy metals by acid washing, desorb organic matter by alkali washing, thereby restoring the porosity of the composite modified biochar filler, and finally supplementing the magnetic component with FeCl3 and CoCl2 solution, repairing carbon skeleton defects at low temperature, and restoring surface functional groups for reuse.

[0040] Further, the molar ratio of FeCl3 and CoCl2 is 2:1.

[0041] Description: When Fe:Co<2:1, Co3O4 is generated, and the magnetism is weak; when Fe:Co>2:1, residual alpha-Fe2O3 is generated, and the diamagnetism interferes with separation.

[0042] The beneficial effects of the present application are:

[0043] (1) The present application innovatively combines clay ceramicization and nitrogen-doped magnetic modification technology to develop a composite biochar with gradient pore structure, adopts a preparation process combining stage pyrolysis and low-temperature electroless deposition, designs an "adsorption-catalytic oxidation" combined system and an intelligent operation method, realizes efficient cooperative treatment of heavy metal-antibiotic composite contaminated wastewater in a specific concentration range, has advantages such as excellent material performance, simple preparation process, stable system operation and strong anti-interference ability, and provides a new solution for heavy metal-antibiotic composite contaminated wastewater treatment.

[0044] (2) The biochar filler prepared by the three-stage temperature control pyrolysis combined with the NH3 activation modification process has the characteristics of large specific surface area, high mechanical strength, and excellent magnetic separation performance, and the preparation process is simple and controllable, and easy to scale production; the filler surface is rich in pyridine nitrogen active sites (accounting for ≥40%) and Fe3O4 catalytic components, which can simultaneously efficiently adsorb heavy metal ions and catalytically degrade antibiotics, realizing the synergistic removal of pollutants. DETAILED DESCRIPTION

[0045] The application will be further described in detail below in combination with specific embodiments to better embody the advantages of the application.

[0046] Embodiment 1: A preparation method of a composite modified biochar filler, comprising the following steps:

[0047] S1, pyrolysis treatment

[0048] First, the agricultural and forestry waste and clay components are mixed in a weight ratio of 2:1, molded under a pressure of 13 MPa, heated to 385℃ at a rate of 7℃ / min under nitrogen protection and kept for 15h, then heated to 575℃ at a rate of 13℃ / min and kept for 15h, and finally heated to 740℃ at a rate of 18℃ / min, when the temperature reaches 700℃, NH3 with a flow rate of 1L / min is introduced and kept for 30h; in S1, the agricultural and forestry waste is corn straw and sawdust mixed in a mass ratio of 3:1, and then crushed to a mixture with a particle size of 50-100μm; the clay component is a mixture of kaolin and montmorillonite in a mass ratio of 7:3;

[0049] S2, modification treatment

[0050] The pyrolysis product is immersed in a modified liquid containing Fe 3+ compound, and then the pH of the modified liquid is adjusted to 10 by a pH adjuster, and electrodeposition is carried out at 50℃ for 30min; in S2, the modified liquid is composed of 18wt% of iron sulfate and 4wt% of polyethyleneimine with a molecular weight of 900Da in a mass ratio of 6:1; in S2, the pH adjuster is ammonia water with a mass concentration of 13wt%;

[0051] S3, secondary calcination

[0052] The product after deposition is mixed with 8wt% of carboxymethyl cellulose to form granules with a particle size of 4mm, and is calcined at 700℃ for 2h under nitrogen protection to obtain a composite modified biochar filler;

[0053] Based on the application of the above-mentioned composite modified biochar filler, it is applied in a heavy metal-antibiotic synergistic removal system;

[0054] The heavy metal-antibiotic synergistic removal system comprises an upflow adsorption tower filled with composite modified biochar filler, a fluidized bed reactor connected in series with the upflow adsorption tower, the fluidized bed reactor being provided with a persulfate dosing device and a magnetic separation device arranged at the end of the system; an ORP online monitor and a Cu 2+ electrode double control, when the ORP is 201 mV or the Cu 2+ concentration is 1 mg / L, the persulfate dosing device of the fluidized bed is automatically started;

[0055] The volume ratio of the upflow adsorption tower to the fluidized bed reactor is 1:1.

[0056] The application method is as follows:

[0057] Step 1: Detect whether the wastewater contains tetracycline antibiotics, the concentration of copper ions and the concentration of sulfonamide antibiotics; in this embodiment, the determined water quality of the influent is: Cu 2+ = 50 mg / L, sulfonamide = 25 mg / L, and pH = 6.8.

[0058] Step 2: Process according to the following method: the filling rate of the composite modified biological filler is 85%.

[0059] (1) The wastewater is introduced into the upflow adsorption tower, and the empty bed contact time is controlled to be 20 min.

[0060] (2) The effluent indicators are monitored in real time, when the Cu 2+ concentration in the effluent of the upflow adsorption tower is 1 mg / L or the ORP is 201 mV, the effluent is immediately introduced into the fluidized bed reactor.

[0061] (3) 1.5 g / L of persulfate and 0.2 g / L of Fe 2+ are added to the fluidized bed reactor to start the oxidation catalytic reaction.

[0062] (4) Finally, the treatment is completed after the magnetic separation device with a magnetic field strength of 0.6 T is treated for 3 min.

[0063] Example 2: Different from example 1, in S1, after being pressed at a pressure of 10 MPa, the temperature is raised to 350℃ at a rate of 5℃ / min under nitrogen protection and kept for 6h, then the temperature is raised to 550℃ at a rate of 10℃ / min and kept for 6h, finally the temperature is raised to 700℃ at a rate of 15℃ / min, when the temperature reaches 700℃, NH3 with a flow rate of 0.5 L / min is introduced and kept for 10h.

[0064] Example 3: Different from Example 1, in S1, after the press forming under the pressure of 15 MPa, the temperature was raised to 420℃ at the rate of 10℃ / min under the protection of nitrogen and kept for 24 h, then the temperature was raised to 600℃ at the rate of 15℃ / min and kept for 24 h, and finally the temperature was raised to 780℃ at the rate of 20℃ / min, when the temperature reached 700℃, NH3 was introduced at the flow rate of 1.5 L / min and kept for 48 h.

[0065] Example 4: Different from Example 1, in S1, the agricultural and forestry wastes were corn stalks and wood chips mixed according to the mass ratio of 2:1, and then the mixture was crushed to the particle size of 50-100 μm.

[0066] Example 5: Different from Example 1, in S1, the agricultural and forestry wastes were corn stalks and wood chips mixed according to the mass ratio of 4:1, and then the mixture was crushed to the particle size of 50-100 μm.

[0067] Example 6: Different from Example 1, in S2, the pH of the modification liquid was adjusted to 9.5 by the pH regulator, and the electrodeposition was carried out at 45℃ for 20 min.

[0068] Example 7: Different from Example 1, in S2, the pH of the modification liquid was adjusted to 10.5 by the pH regulator, and the electrodeposition was carried out at 55℃ for 40 min.

[0069] Example 8: Different from Example 1, in S2, the modification liquid was composed of 15wt% of ferric sulfate and 2wt% of polyethyleneimine with the molecular weight of 800 Da according to the mass ratio of 2.5:1.

[0070] Example 9: Different from Example 1, in S2, the modification liquid was composed of 20wt% of ferric sulfate and 6wt% of polyethyleneimine with the molecular weight of 1000 Da according to the mass ratio of 10:1.

[0071] Example 10: Different from Example 1, in S2, the pH regulator was ammonia water with the mass concentration of 10wt%.

[0072] Example 11: Different from Example 1, in S2, the pH regulator was sodium hydroxide solution with the mass concentration of 8wt%.

[0073] Example 12: Different from Example 1, in S3, the product after deposition was mixed with 5wt% of carboxymethyl cellulose to form granules with the particle size of 2 mm, and then the granules were calcined at 600℃ for 1 h under the protection of nitrogen at the rate of 5℃ / min to obtain the composite modified biochar filler.

[0074] Example 13: Different from Example 1, in S3, the product after deposition was mixed with 10wt% carboxymethyl cellulose to form granules with a particle size of 5mm, and then the granules were subjected to secondary calcination at 800℃ for 3h under nitrogen protection at a temperature increasing rate of 20℃ / min to obtain the composite modified biochar filler.

[0075] Example 14: Different from Example 1, the composite modified biofiller was treated according to the following method: the filling rate of the composite modified biofiller was 70%;

[0076] (1) The wastewater was introduced into the upflow adsorption tower, and the empty bed contact time was controlled to be 15min;

[0077] (2) The effluent indicators were monitored in real time, and when the Cu 2+ concentration in the effluent of the upflow adsorption tower was 1mg / L or the ORP was 201mV, the effluent was immediately introduced into the fluidized bed reactor;

[0078] (3) 1g / L persulfate and 0.1g / L Fe 2+ were added to the fluidized bed reactor to start the oxidation catalytic reaction;

[0079] (4) Finally, the treatment was completed after the magnetic separation device with a magnetic field strength of 0.5T was treated for 1min.

[0080] Example 15: Different from Example 1, the composite modified biofiller was treated according to the following method: the filling rate of the composite modified biofiller was 90%;

[0081] (1) The wastewater was introduced into the upflow adsorption tower, and the empty bed contact time was controlled to be 30min;

[0082] (2) The effluent indicators were monitored in real time, and when the Cu 2+ concentration in the effluent of the upflow adsorption tower was 1mg / L or the ORP was 201mV, the effluent was immediately introduced into the fluidized bed reactor;

[0083] (3) 2g / L persulfate and 0.3g / L Fe 2+ were added to the fluidized bed reactor to start the oxidation catalytic reaction;

[0084] (4) Finally, the treatment was completed after the magnetic separation device with a magnetic field strength of 0.8T was treated for 5min.

[0085] Example 16: Different from example 1, the magnetic separation device end also has a filler regeneration module, after the treatment, the composite modified biochar filler is taken out, 0.3 mol / L of HC1 solution is added to the composite modified biochar filler according to the solid-liquid ratio of 5 mL: 1 g, the oscillation speed is 135 rpm under the condition of 24℃, and the oscillation is carried out for 28 min, then 0.1 mol / L of NaOH solution and 10% of ethanol by volume concentration are added, the treatment is carried out under the condition of 48℃, 38 kHz of ultrasonic frequency and 95 W of ultrasonic power for 18 min, finally the composite modified biochar filler is immersed in the FeCl3 and CoCl2 solution with a total concentration of 0.1 mol / L, and the electroless deposition is carried out under the condition of pH = 9.5 and 53℃ for 28 min, and the regenerated composite modified biochar filler is obtained; the molar ratio of FeCl3 and CoCl2 is 2:1.

[0086] Example 17: Different from example 16, 0.1 mol / L of HC1 solution is added to the composite modified biochar filler according to the solid-liquid ratio of 5 mL: 1 g, the oscillation speed is 120 rpm under the condition of 22℃, and the oscillation is carried out for 25 min.

[0087] Example 18: Different from example 16, 0.5 mol / L of HC1 solution is added to the composite modified biochar filler according to the solid-liquid ratio of 5 mL: 1 g, the oscillation speed is 150 rpm under the condition of 25℃, and the oscillation is carried out for 30 min.

[0088] Example 19: Different from example 16, then 0.1 mol / L of NaOH solution and 10% of ethanol by volume concentration are added, and the treatment is carried out under the condition of 45℃, 35 kHz of ultrasonic frequency and 90 W of ultrasonic power for 15 min.

[0089] Example 20: Different from example 16, then 0.1 mol / L of NaOH solution and 10% of ethanol by volume concentration are added, and the treatment is carried out under the condition of 50℃, 40 kHz of ultrasonic frequency and 100 W of ultrasonic power for 20 min.

[0090] Example 21: Different from example 16, finally the composite modified biochar filler is immersed in the FeCl3 and CoCl2 solution with a total concentration of 0.1 mol / L, and the electroless deposition is carried out under the condition of pH = 9.5 and 50℃ for 25 min, and the regenerated composite modified biochar filler is obtained.

[0091] Example 22: Unlike Example 16, the composite modified biochar filler was finally immersed in a FeCl3 and CoCl2 solution with a total concentration of 0.1 mol / L, and electrodeposited for 30 min at pH 9.5 and 55°C to obtain the regenerated composite modified biochar filler.

[0092] Experimental Example 1: Investigating the effects of various parameters in the treatment method on the heavy metal-antibiotic removal efficiency of the composite modified biochar packing.

[0093] Examples 1, 14, and 15 were compared to verify the effect of parameter differences in the composite modified biochar packing material on the treatment effect under different schemes. The results are as follows:

[0094] Table 1. Removal efficacy of composite modified biochar packing materials obtained in Examples 1, 14-15 for heavy metals and antibiotics.

[0095] Group Cu effluent 2+ Concentration mg / L Sulfonamide concentration mg / L in effluent Example 14 0.295 0.048 Example 1 0.283 0.0482 Example 15 0.275 0.049

[0096] Conclusion: Testing showed that the composite modified biochar packing material, through adjustments to differentiated parameters (contact time, reagent dosage, and packing filling rate), could achieve "Cu" results under various pollution scenarios. 2+ The effluent targets of "≤0.3 mg / L for sulfonamides and ≤0.05 mg / L for sulfuramides" were used to verify the multi-scenario adaptability of the composite modified biochar packing material, and to improve the overall effluent Cu content. 2+ The concentrations of sulfonamides in the effluent and the concentration of sulfonamides in the effluent show that Example 1 has the optimal parameters.

[0097] 2. Investigating the effect of pyrolysis treatment on the removal efficiency of heavy metals and antibiotics by composite modified biochar packing. Table 2 shows the removal efficiency of heavy metals and antibiotics by the composite modified biochar packing obtained in Examples 1-9 and Control Examples 1-Control Examples 3.

[0098]

[0099]

[0100] Comparative Example 1: Unlike Example 1, during the pyrolysis process, the temperature was increased to 740°C at a rate of 7°C / min under nitrogen protection. When the temperature reached 700°C, NH3 was introduced at a flow rate of 1L / min and the temperature was maintained for 30 hours.

[0101] Comparative Example 2: Unlike Example 1, the agricultural and forestry waste does not contain sawdust.

[0102] Comparative Example 3: Unlike Example 1, the modified liquid does not contain polyethyleneimine.

[0103] Conclusion: From the comparison of Example 1, Example 2-Example 3 and Control Example 1, it can be seen that direct heating has an adverse effect on the removal of heavy metals-antibiotics by composite modified biochar filler, mainly because gradient heating can promote the stepwise decomposition of biomass components through staged pyrolysis: hemicellulose degradation in the low-temperature stage (385℃) to form an initial pore framework; the middle-temperature stage (575℃) promotes lignin carbonization to expand the mesoporous structure; the high-temperature stage (740℃) completes graphitization and introduces nitrogen-containing functional groups in the NH3 atmosphere; while the control example directly heats to 740℃, which causes volatile matter to escape instantaneously, resulting in pore collapse and a decrease in specific surface area; when NH3 is introduced at 700℃, the abundant pores formed by gradient heating can adsorb more NH3 molecules to generate active sites such as pyridine nitrogen / pyrrole nitrogen; direct heating has insufficient pore development, and the nitrogen doping efficiency decreases;

[0104] Cu 2+ Depends on pore physical adsorption and chelation of nitrogen-containing functional groups, the reduction of pores leads to a decrease in adsorption capacity, and Fe 3+ / nitrogen co-catalytic activation of persulfate is required for sulfonamide degradation, direct heating reduces the loading of Fe 3+ ;

[0105] From the comparison of Example 1, Example 4, Example 5 and Control Example 2, it can be seen that the absence of sawdust in agricultural and forestry waste has an adverse effect on the removal of heavy metals-antibiotics by composite modified biochar filler, mainly because sawdust is rich in lignin, which forms a graphitized microcrystalline structure during high-temperature pyrolysis (740℃), enhancing the mechanical strength and pore stability of the biochar; without sawdust, the corn straw-dominated pyrolysis products are mainly cellulose-derived pores, with a reduced proportion of mesopores, leading to a decrease in adsorption capacity; and the aromatic carbon structure generated by sawdust pyrolysis is more easily reacted with NH3 to generate pyridine nitrogen / pyrrole nitrogen functional groups, enhancing the chelation ability of Cu 2+ ; while the nitrogen doping efficiency of Control Example 2 is reduced, affecting the density of heavy metal adsorption active sites; at the same time, the hierarchical pores derived from sawdust can optimize the dispersity of Fe 3+ ; without sawdust, Fe 3+ is prone to aggregation, and the efficiency of catalytic activation of persulfate is reduced; Cu 2+ removal depends on pore physical adsorption and chelation of nitrogen functional groups, the reduction of porosity and functional groups leads to a decrease in adsorption capacity, and Fe 3+ / persulfate system catalysis is required for sulfonamide degradation, and the aggregation of Fe 3+ reduces the efficiency of sulfonamide degradation;

[0106] From the comparison of Example 1, Example 8, Example 9 and Control Example 3, it can be seen that the absence of polyethyleneimine in the modification liquid has an adverse effect on the removal of heavy metals-antibiotics by composite modified biochar filler, mainly because the amine group (-NH2) of PEI stabilizes and fixes Fe3+ The absence of PEI will lead to a large amount of Fe in the modified solution 3+ Unable to effectively load on the surface of biochar, forming free or agglomerated ineffective iron components; PEI is protonated to form -NH3 under the condition of pH = 10 + , giving the biochar positive charge to enhance the electrostatic adsorption of anionic pollutants (such as sulfonamides); the absence of which will weaken the electrostatic adsorption effect; at the same time, PEI-Fe 3+ complex as an electron transfer medium, can activate persulfate to generate reactive oxygen free radicals (·OH / SO4· - ); the amount of free radicals generated decreases without PEI, and the efficiency of sulfonamide oxidative degradation decreases sharply; Cu 2+ remove the amine chelation dependent on PEI, the absence of PEI reduces the density of metal binding sites, leading to a decrease in adsorption capacity; sulfonamide degradation requires PEI-Fe 3+ complex catalytic system, the catalytic efficiency of Fe 3+ alone decreases, thereby reducing the degradation efficiency of sulfonamides.

[0107] 3. Explore the influence of filler regeneration on the heavy metal-antibiotic removal effect of composite modified biochar filler

[0108] Table 3 Heavy metal-antibiotic removal effect of composite modified biochar filler obtained from Example 1, Example 16-Example 22 and Control Example 4-Control Example 6

[0109] Group Cu effluent 2+ Concentration mg / L Sulfonamide concentration mg / L in effluent Example 1 0.283 0.0482 Example 16 0.226 0.035 Example 17 0.229 0.037 Example 18 0.231 0.035 Example 19 0.228 0.036 Example 20 0.230 0.036 Example 21 0.229 0.038 Example 22 0.228 0.037 Control 4 0.281 0.0477 Control 5 0.26 0.048 Control 6 0.279 0.048

[0110] Control Example 4: Unlike Example 16, it lacks the HCl treatment step.

[0111] Control Example 5: Unlike Example 16, it lacks the composite treatment of NaOH solution and ethanol.

[0112] Control Example 6: Unlike Example 16, it lacks the loading step of FeCl3 and CoCl2 solution.

[0113] Conclusion: From the comparison of Example 1, Example 16-Example 24, it can be seen that the increased filler regeneration module has a positive effect on improving the heavy metal-antibiotic removal effect of composite modified biochar filler, mainly because HCl cleaning can effectively remove the heavy metal precipitates (such as Cu 2+ or iron oxide) accumulated on the surface of the filler, restoring the pore structure and specific surface area; the subsequent NaOH / ethanol treatment hydrolyzes and ultrasonically peels off organic dirt (such as sulfonamide residues), increasing the exposure rate of biochar surface functional groups (such as carboxyl and hydroxyl) by ≥25%, strengthening the adsorption of Cu 2+The chelating ability; an electrodeposition process in which FeCl3 / CoCl2 solution is immersed in the solution to form uniformly loaded Fe-Co bimetallic nanoparticles (particle size <100nm) at pH 9.5 and 50-55℃. 2+ As a persulfate activation promoter, with Fe 3+ Synergistic reduction of free radicals (·OH / SO4·) - The formation of an energy barrier improves the oxidative degradation efficiency of sulfonamides, thereby optimizing Cu. 2+ The removal effect of sulfonamides; and the regeneration process through acid-alkali-ethanol treatment can eliminate biofilm blockage and inorganic scaling on the packing surface; the loaded Fe-Co nanoparticles form a stable oxide layer in a high pH environment, avoiding deactivation of active sites and ensuring that the system maintains a high removal rate during continuous operation; and the comparison of Examples 16-24 shows that Example 16 is the optimal solution.

[0114] A comparison of Examples 16-18 and Control Example 4 shows that the absence of the HCl treatment step negatively impacts the removal of heavy metals and antibiotics from the composite modified biochar packing. This is mainly because HCl cleaning dissolves Cu(OH)2 colloids and carbonate precipitates (such as CuCO3) formed in an alkaline environment, restoring the specific surface area of ​​the biochar. Without this step, the precipitate coverage increases, shielding Fe / Co active sites and leaving residual Cu... 2+ Fe3+ with subsequent load + / Co 2+ Competition for persulfate activation sites weakens bimetallic catalytic activity; undisturbed inorganic precipitates adsorb sulfonamide organic compounds, forming a complex fouling layer that hinders the ·OH / SO4· - Free radicals contact the target pollutant; residual Cu 2+ Consume reduction electrons (Fe) in the system 3+ →Fe 2+ The conversion requires electrons, which terminates the free radical chain reaction, thereby yielding water Cu. 2+ Concentrations of sulfonamides in the effluent and concentrations in the effluent have rebounded.

[0115] A comparison of Examples 16, 19-20, and Comparative Example 5 reveals that the absence of the combined treatment with NaOH solution and ethanol negatively impacts the heavy metal and antibiotic removal efficiency of the composite modified biochar packing. This is primarily because the core function of the NaOH / ethanol combined treatment is to remove residual sulfonamide organic matter after acid washing. The absence of this step leads to the formation of a dense organic film from the unremoved sulfonamides, which covers the subsequently loaded Fe / Co active sites, hindering free radical generation. Furthermore, the NaOH / ethanol treatment enhances heavy metal adsorption capacity through dual activation; the absence of this step results in pore blockage and Cu... 2+The contact active site probability decreases, and the adsorption capacity decays; and the alkaline washing step can provide an optimized interface environment for Fe / Co loading, and the absence thereof can cause the loaded Fe / Co nanoparticles to agglomerate, leading to the generation of SO4· by catalyzing persulfate. - The efficiency of the modified biochar is reduced;

[0116] As can be seen from the comparison of Examples 16, 21-22 and Comparative Example 6, the absence of the FeCl3 and CoCl2 solution loading step can adversely affect the heavy metal-antibiotic removal efficiency of the composite modified biochar filler, mainly because Fe 3+ and Co 2+ synergistically reduce the activation energy barrier of persulfate (PMS), promoting the generation of ·OH / SO4· - radicals (the rate is increased by 5.27 times). After the absence thereof, sulfonamides only rely on physical adsorption, and the degradation rate drops sharply; Fe 3+ and Cu 2+ compete for replacement (Fe 3+ + Cu 2+ → Fe 2+ + Cu 3+ ), enhancing the immobilization of Cu 2+ ; at the same time, the Fe / Co oxide surface is positively charged at pH = 9.5, strongly adsorbing Cu 2+ ; without loading, the electrostatic adsorption capacity is weakened; and the absence of the magnetic responsiveness of the Fe / Co endows the filler leads to an increase in the loss rate of the filler, and the system is insufficient in retention.

Claims

1. A method for preparing a composite modified biochar filler, characterized in that, Includes the following steps: S1, Pyrolysis treatment First, agricultural and forestry waste and clay components are mixed at a weight ratio of 2:

1. After being pressed into shape under a pressure of 10-15 MPa, the mixture is heated to 350-420℃ at a rate of 5-10℃ / min under nitrogen protection and held for 6-24 hours. Then, the temperature is raised to 550-600℃ at a rate of 10-15℃ / min and held for 6-24 hours. Finally, the temperature is raised to 700-780℃ at a rate of 15-20℃ / min. When the temperature reaches 700℃, NH3 is introduced at a flow rate of 0.5-1.5 L / min and held for 10-48 hours. S2, Modification Treatment The pyrolysis product was impregnated with an Fe-containing solution. 3+ In the modified solution of the compound, the pH of the modified solution was adjusted to 9.5-10.5 by pH adjuster, and electrodeposition was carried out at 45-55℃ for 20-40 min without electrodeposition. S3, Secondary calcination The deposited product is mixed with 5-10 wt% carboxymethyl cellulose and granulated to form particles with a particle size of 2-5 mm. The particles are then calcined for 1-3 h at a temperature of 600-800 °C under nitrogen protection at a rate of 5-20 °C / min to obtain the composite modified biochar filler.

2. The method for preparing a composite modified biochar filler as described in claim 1, characterized in that, In S1, the agricultural and forestry waste is a mixture of corn stalks and sawdust mixed in a mass ratio of 2-4:1 and then crushed to a particle size of 50-100μm; the clay component is a mixture of kaolin and montmorillonite mixed in a mass ratio of 7:

3.

3. The method for preparing a composite modified biochar filler as described in claim 1, characterized in that, In S2, the modified liquid is composed of 15-20 wt% ferric sulfate and 2-6 wt% polyethyleneimine with a molecular weight of 800-1000 Da in a mass ratio of 2.5-10:

1.

4. The method for preparing a composite modified biochar filler as described in claim 1, characterized in that, In S2, the pH adjuster is a sodium hydroxide solution with a mass concentration of 5-8 wt% or an ammonia solution with a mass concentration of 10-15 wt%.

5. The application of the composite modified biochar packing material as described in any one of claims 1-4, characterized in that, It was applied to a heavy metal-antibiotic synergistic removal system. The heavy metal-antibiotic synergistic removal system includes an upflow adsorption tower filled with the composite modified biochar packing material, a fluidized bed reactor connected in series with the upflow adsorption tower, the fluidized bed reactor being equipped with a persulfate dosing device and a magnetic separation device located at the end of the system; an ORP online monitoring instrument and a Cu2O2 monitoring instrument are installed at the outlet of the adsorption tower. 2+ Dual electrode control, when ORP > 200mV or Cu 2+ When the concentration is ≤1 mg / L, the persulfate dosing device of the fluidized bed will be automatically activated; The volume ratio of the upflow adsorption tower to the fluidized bed reactor is 1:0.5-1.5; the empty bed contact time of the upflow adsorption tower is 10-45 min; the dosage of persulfate is 0.5-3 g / L; and the magnetic field strength in the magnetic separation device is 0.5-0.8 T.

6. The application of the composite modified biochar packing material as described in claim 5, characterized in that, The composite modified biological filler has a filling rate of ≥70-90%.

7. The application of the composite modified biochar packing material as described in claim 5, characterized in that, The method of application is as follows: Step 1: Test the wastewater for the presence of tetracycline antibiotics, copper ion concentration, and sulfonamide antibiotic concentration; Step 2: When the wastewater contains tetracycline antibiotics and the copper ion concentration is <10 mg / L, and the sulfonamide antibiotic concentration is <5 mg / L, treat it as follows: (1) Pass the wastewater into the upflow adsorption tower and control the empty bed contact time to be 10-15 min; (2) Real-time monitoring of effluent indicators; when Cu in the effluent of the upflow adsorption tower... 2+ When the concentration is ≤1mg / L or ORP>200mV, the effluent should be immediately introduced into the fluidized bed reactor; (3) Add 0.5-1 g / L persulfate and 0.05-0.1 g / L Fe to the fluidized bed reactor. 2+ Initiate the oxidation catalytic reaction; (4) Finally, the process is completed after being processed by a magnetic separation device with a magnetic field strength of 0.5-0.8T for 1-5 minutes. When the wastewater contains tetracycline antibiotics and the copper ion concentration is 10-100 mg / L, and the sulfonamide antibiotic concentration is 5-50 mg / L, adjust the hollow bed contact time in (1) to 15-30 min; at the same time, add 1-2 g / L of persulfate and 0.1-0.3 g / L of Fe to the fluidized bed reactor in (3). 2+ The oxidation catalytic reaction is initiated; the remaining steps remain unchanged. When the wastewater contains tetracycline antibiotics and the copper ion concentration is >100 mg / L, and the sulfonamide antibiotic concentration is >50 mg / L, adjust the hollow bed contact time in (1) to 30-45 min; at the same time, add 2-3 g / L of persulfate and 0.3-0.5 g / L of Fe to the fluidized bed reactor in (3). 2+ The oxidation catalytic reaction is initiated; the remaining steps remain unchanged.

8. The application of the composite modified biochar packing material as described in claim 7, characterized in that, The magnetic separation device also has a packing regeneration module at the end. After processing, the composite modified biochar packing is taken out. First, 0.1-0.5 mol / L HCl solution is added to the composite modified biochar packing at a solid-liquid ratio of 5 mL:1 g. The packing is shaken for 25-30 min at a temperature of 22-25℃ and a shaking speed of 120-150 rpm. Then, 0.1 mol / L NaOH solution and 10% ethanol are added. The packing is treated for 15-20 min at a temperature of 45-50℃, an ultrasonic frequency of 35-40 kHz, and an ultrasonic power of 90-100 W. Finally, the composite modified biochar packing is immersed in a FeCl3 and CoCl2 solution with a total concentration of 0.1 mol / L. Electrodeposition is performed for 25-30 min at a pH of 9.5 and a temperature of 50-55℃ to obtain the regenerated composite modified biochar packing.

9. The application of the composite modified biochar filler as described in claim 8, characterized in that, The molar ratio of FeCl3 to CoCl2 is 2:1.

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