Catalytic treatment process for glufosinate-ammonium production wastewater

Abstract

The invention discloses a catalytic treatment process of glufosinate-ammonium production wastewater, which comprises the following steps: introducing glufosinate-ammonium production wastewater into an electrocatalytic oxidation pond, and adding a graphite plate as an anode, a stainless steel plate as a cathode and iron-impregnated composite powder as a particle electrode into the electrocatalytic oxidation pond for electrifying catalysis, and filtering to finish the catalytic treatment of the glufosinate-ammonium production wastewater. According to the catalytic treatment process disclosed by the invention, the iron-impregnated composite powder with adsorption, complexation and precipitation capacities on phosphate and magnesium ions is prepared, and the phosphate and the magnesium ions are adsorbed and catalytically oxidized by utilizing an electrocatalytic oxidation technology and a primary battery formed by the iron-impregnated composite powder in glufosinate-ammonium production wastewater; under the electrocatalytic oxidation technology, the adsorbed phosphate and magnesium ion precipitate are removed, and phosphorus discharge and magnesium discharge in glufosinate-ammonium production wastewater are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a catalytic treatment process for glufosinate-ammonium production wastewater. Background Art

[0002] As a broad-spectrum, non-selective, post-emergence herbicide of the organophosphorus type, glufosinate-ammonium has the characteristics of high activity, good absorption, broad herbicide spectrum, low toxicity, and good environmental compatibility. The Strcker method is a synthesis method commonly used by domestic production enterprises. This method uses triethyl phosphite as a raw material and obtains 95% glufosinate-ammonium technical powder through 8-step reactions such as disproportionation, formatting, methylation, addition, cyanidation, acidolysis, ammoniation, and purification reactions. However, a large amount of glufosinate-ammonium production wastewater containing magnesium and phosphorus will be generated. Direct discharge of the wastewater will cause environmental pollution and eutrophication of water bodies. Therefore, it is necessary to treat the glufosinate-ammonium production wastewater before discharging it.

[0003] Patent CN118513053A discloses a preparation method and application of a Mn, Fe, Ru-doped titanium dioxide catalyst. By precisely controlling the molar ratio of Mn, Fe, Ru to Ti, the effective doping of the active components of the catalyst is ensured, with high dispersion, higher catalytic activity and selectivity, and the synergistic effect between metals improves the catalytic activity of the catalyst. However, this scheme has fewer surface active sites, a small doping area, and is easily attached by precipitates, resulting in low catalytic efficiency.

[0004] Patent CN108751599A discloses a method for treating glufosinate-ammonium pesticide wastewater with highly efficient biological strains, including physical and chemical treatment first, then biochemical treatment, and finally precipitation and separation. The supernatant is discharged, and the sludge is transported out for treatment. The physical and chemical treatment includes chemical phosphorus removal, Fe-C micro-electrolysis, and Fenton oxidation carried out sequentially. The biochemical treatment includes a combined treatment of multi-stage anaerobic and aerobic processes. However, biological treatment takes a long time, and the amount of sludge generated will also increase significantly, increasing the treatment cost of the sludge.

[0005] The electrocatalytic oxidation technology for treating wastewater can efficiently remove the COD content in water and can be used to treat nitrogen, phosphorus, and magnesium elements in glufosinate-ammonium production wastewater, reducing environmental pollution and eutrophication of water bodies caused by the discharged sewage. However, the particle electrode in the electrocatalytic oxidation technology is activated carbon, and the adsorption force of activated carbon for magnesium ions and phosphates is low, and it is easily occupied by other organic substances in the adsorption pores, resulting in a low removal rate of magnesium ions and phosphates. Summary of the Invention

[0006] The purpose of the present invention is to solve how to improve the treatment efficiency of magnesium ions and phosphates in the catalytic treatment of glufosinate-ammonium production wastewater by electrocatalytic oxidation technology, and to provide a catalytic treatment process for glufosinate-ammonium production wastewater.

[0007] In the present invention, an iron-impregnated composite powder with the ability to adsorb and precipitate phosphate and magnesium ions is used as a particle electrode in the electrocatalytic oxidation technology, which improves the adsorption and precipitation of phosphate and magnesium ions in the glufosinate production wastewater and enhances the catalytic treatment efficiency.

[0008] The object of the present invention can be achieved by the following technical solutions:

[0009] A catalytic treatment process for glufosinate production wastewater includes the following steps:

[0010] The glufosinate production wastewater is introduced into an electrocatalytic oxidation cell. Using a graphite plate as the anode and a stainless steel plate as the cathode, the iron-impregnated composite powder is added as a particle electrode into the electrocatalytic oxidation cell for electrocatalytic treatment under an electric current. After filtration, the catalytic treatment of the glufosinate production wastewater is completed.

[0011] The iron-impregnated composite powder is prepared by the following steps:

[0012] The porous zirconia powder is compounded with graphene nanosheets to obtain a composite powder. In a reaction kettle, the composite powder and ferric nitrate nonahydrate are stirred and mixed in deionized water for 20 - 30 min, then a sodium borohydride solution with a concentration of 1.2 - 1.5 M is added. After centrifugal filtration, the precipitate is washed, and vacuum dried to obtain the iron-impregnated composite powder.

[0013] Further, the dosage ratio of the iron-impregnated composite powder to the glufosinate production wastewater is 10 - 15 g : 1 - 1.5 L, the current density is 30 - 50 mA·cm -2 , and the power-on time is 90 - 120 min.

[0014] Further, the dosage ratio of the composite powder, ferric nitrate nonahydrate, deionized water, and sodium borohydride solution is 10 - 15 g : 30 - 40 g : 1000 - 1250 mL : 120 - 150 mL.

[0015] Further, the composite powder is specifically prepared by the following steps:

[0016] In a reaction kettle, the porous zirconia powder is ultrasonically dispersed in deionized water to obtain a zirconia dispersion, and then the modified graphene nanosheets are ultrasonically dispersed in deionized water to obtain a graphene dispersion. The zirconia dispersion and the graphene dispersion are mixed in equal volume, and vigorously stirred for 4 - 5 h. The precipitate is collected by centrifugation and vacuum dried at 60 - 70 °C to obtain the composite powder.

[0017] Further, the concentration of the zirconia dispersion is 10 - 15 g / L, and the concentration of the graphene dispersion is 25 - 35 g / L.

[0018] Further, the porous zirconia powder is prepared by the following steps:

[0019] The precursor powder and nano-calcium carbonate powder are stirred and mixed in ethanol for 20 - 24 h. After filtration, the powder is granulated with a 50 wt% polyvinylpyrrolidone solution as the binder to obtain calcium carbonate / precursor composite powder. The calcium carbonate / precursor composite powder is calcined in a reaction kettle at 400 - 500 °C in air for 2 - 3 h to obtain porous zirconia powder.

[0020] Furthermore, the mass ratio of the precursor powder to the nano-calcium carbonate powder is 2.5 - 3:0.8 - 1.

[0021] Furthermore, the modified graphene nanosheets are prepared by the following steps:

[0022] N-[3-(Trimethoxysilyl)propyl]ethylenediamine is stirred and dispersed in a 70 wt% ethanol solution in a reaction kettle. The pH value of the ethanol solution is adjusted to 4 - 5 with acetic acid. Graphene oxide nanosheets with a diameter of 1 - 3 μm are added to the reaction kettle and stirred and dispersed for 4 - 5 h. The precipitate is collected by centrifugation, washed, and then dried in vacuo to obtain the modified graphene nanosheets.

[0023] Furthermore, the dosage ratio of N-[3-(trimethoxysilyl)propyl]ethylenediamine, the ethanol solution, and the graphene oxide nanosheets is 5 - 7 g:1000 - 1500 mL:10 - 20 g.

[0024] Furthermore, the precursor powder is prepared by the following steps:

[0025] Zirconium tetrachloride and terephthalic acid are stirred and dissolved in N,N-dimethylformamide and formic acid in a reaction kettle, heated to 120 - 130 °C and reacted for 20 - 24 h. After cooling, filtration is carried out. The precipitate is washed and then dried in vacuo to obtain the precursor powder.

[0026] Furthermore, the dosage ratio of zirconium tetrachloride, terephthalic acid, N,N-dimethylformamide, and formic acid is 10 - 12 g:6 - 8 g:800 - 1000 mL:60 - 80 mL.

[0027] Advantages of the present invention:

[0028] (1) The catalytic treatment process of the present invention prepares an iron-impregnated composite powder with the ability to adsorb, complex, and precipitate phosphate and magnesium ions. By using electrocatalytic oxidation technology and the primary battery formed by the iron-impregnated composite powder in the glufosinate-ammonium production wastewater, phosphate and magnesium ions are adsorbed and catalytically oxidized. Under the electrocatalytic oxidation technology, the adsorbed phosphate and magnesium ions are precipitated and removed, reducing the phosphorus and magnesium emissions in the glufosinate-ammonium production wastewater.

[0029] (2) The catalytic treatment process of the present invention forms porous zirconia powder by calcining porous precursor powder, increases the specific surface area of the zirconia powder, and improves the adsorption capacity in the glyphosate production wastewater. By compounding calcium carbonate and precursor powder, the agglomeration phenomenon during the formation of zirconia is reduced. Calcium ions can reduce the electrostatic repulsion between phosphate and zirconia, and improve the adsorption of phosphate by zirconia. By compounding porous zirconia powder with graphene oxide, the aqueous solution dispersibility of the composite powder is improved, and a carbon source is provided at the same time. By impregnating iron on graphene oxide to generate nano iron particles, a primary battery is formed with graphene oxide, and the adsorption and precipitation capacity of the iron-impregnated composite powder is improved. Detailed implementation manners

[0030] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] Example 1: A catalytic treatment process for glyphosate production wastewater, comprising the following steps:

[0032] S1. Stir and dissolve 10 g of zirconium tetrachloride and 6 g of terephthalic acid in 800 mL of N,N-dimethylformamide and 60 mL of formic acid in a reaction kettle, heat up to 120 °C and react for 20 h, filter after cooling, and wash the precipitate with N,N-dimethylformamide, methanol and deionized water respectively, and vacuum dry at 70 °C for 12 h to obtain precursor powder.

[0033] S2. Stir and mix the precursor powder and nano calcium carbonate powder in ethanol at a mass ratio of 2.5:0.8 for 20 h. After filtration, use 50 wt% polyvinylpyrrolidone solution as the binder for the powder, press at a uniaxial pressure of 50 MPa for 30 s, and then apply a pressure of 450 MPa for 30 s to granulate to obtain calcium carbonate / precursor composite powder. Calcine the calcium carbonate / precursor composite powder in air at 400 °C for 2 h in a reaction kettle to obtain porous zirconia powder.

[0034] S3. Stir and disperse 5 g of N-[3-(trimethoxysilyl)propyl]ethylenediamine in 1000 mL of 70 wt% ethanol solution in a reaction kettle, adjust the pH value of the ethanol solution to 4 with acetic acid, add 10 g of graphene oxide nanosheets with a diameter of 1 μm to the reaction kettle, stir and disperse for 4 h, centrifuge to collect the precipitate, wash with deionized water and ethanol, and vacuum dry at 60 °C for 20 h to obtain modified graphene oxide nanosheets.

[0035] S4. Ultrasonically disperse the porous zirconia powder in deionized water in a reaction kettle to prepare a zirconia dispersion with a concentration of 10 g / L. Then, ultrasonically disperse the modified graphene nanosheets in deionized water to prepare a graphene dispersion with a concentration of 25 g / L. Mix the zirconia dispersion and the graphene dispersion in equal volumes, stir vigorously for 4 h, centrifuge to collect the precipitate, and dry it in vacuo at 60 °C to obtain the composite powder.

[0036] S5. In a reaction kettle, stir and mix 10 g of the composite powder and 30 g of ferric nitrate nonahydrate in 1000 mL of deionized water for 20 min. Then, add 120 mL of a sodium borohydride solution with a concentration of 1.2 M. After centrifuging and filtering, wash the precipitate with deionized water and dry it in vacuo at 70 °C for 12 h to obtain the iron-impregnated composite powder.

[0037] S6. Pass the glufosinate production wastewater into an electrocatalytic oxidation cell. Use a graphite plate as the anode and a stainless steel plate as the cathode. Add the iron-impregnated composite powder as the particle electrode to the electrocatalytic oxidation cell. The dosage ratio of the iron-impregnated composite powder to the glufosinate production wastewater is 10 g:1 L, and the current density is 30 mA·cm -2 , and the power-on time is 90 min. After filtration, the catalytic treatment of the glufosinate production wastewater is completed.

[0038] Example 2: A catalytic treatment process for glufosinate production wastewater, including the following steps:

[0039] S1. Stir and dissolve 11 g of zirconium tetrachloride and 7 g of terephthalic acid in 900 mL of N,N-dimethylformamide and 70 mL of formic acid in a reaction kettle, heat up to 125 °C and react for 22 h. After cooling, filter, and wash the precipitate with N,N-dimethylformamide, methanol, and deionized water respectively, and dry it in vacuo at 75 °C for 14 h to obtain the precursor powder.

[0040] S2. Stir and mix the precursor powder and the nano-calcium carbonate powder in ethanol according to a mass ratio of 2.7:0.9 for 22 h. After filtration, use a 50 wt% polyvinylpyrrolidone solution as the binder for the powder, press it at a uniaxial pressure of 55 MPa for 33 s, and then apply a pressure of 475 MPa for 33 s to granulate and obtain the calcium carbonate / precursor composite powder. In a reaction kettle, calcine the calcium carbonate / precursor composite powder in air at 450 °C for 2.5 h to obtain the porous zirconia powder.

[0041] S3. Stir and disperse 6 g of N-[3-(trimethoxysilyl)propyl]ethylenediamine in 1250 mL of a 70 wt% ethanol solution in a reaction kettle, adjust the pH value of the ethanol solution to 4.5 with acetic acid, add 15 g of graphene oxide nanosheets with a diameter of 2 μm to the reaction kettle, stir and disperse for 4.5 h, centrifuge to collect the precipitate, wash it with deionized water and ethanol, and dry it in vacuo at 65 °C for 22 h to obtain the modified graphene nanosheets.

[0042] S4. Ultrasonically disperse the porous zirconia powder in deionized water in a reaction kettle to prepare a zirconia dispersion with a concentration of 12.5 g / L. Then ultrasonically disperse the modified graphene nanosheets in deionized water to prepare a graphene dispersion with a concentration of 30 g / L. Mix the zirconia dispersion and the graphene dispersion in equal volumes, stir vigorously for 4.5 h, centrifuge to collect the precipitate, and dry it in vacuo at 65 °C to obtain the composite powder.

[0043] S5. In a reaction kettle, stir and mix 12.5 g of the composite powder and 35 g of ferric nitrate nonahydrate in 1125 mL of deionized water for 25 min. Then add 135 mL of a sodium borohydride solution with a concentration of 1.35 M. After centrifugation and filtration, wash the precipitate with deionized water and dry it in vacuo at 75 °C for 14 h to obtain the iron-impregnated composite powder.

[0044] S6. Feed the glufosinate production wastewater into an electrocatalytic oxidation cell. Use a graphite plate as the anode and a stainless steel plate as the cathode. Add the iron-impregnated composite powder as the particle electrode into the electrocatalytic oxidation cell. The dosage ratio of the iron-impregnated composite powder to the glufosinate production wastewater is 12.5 g: 1.25 L, and the current density is 40 mA·cm -2 , and the power-on time is 110 min. After filtration, the catalytic treatment of the glufosinate production wastewater is completed.

[0045] Example 3: A catalytic treatment process for glufosinate production wastewater, comprising the following steps:

[0046] S1. Stir and dissolve 12 g of zirconium tetrachloride and 8 g of terephthalic acid in 1000 mL of N,N-dimethylformamide and 80 mL of formic acid in a reaction kettle, heat up to 130 °C and react for 24 h. After cooling, filter, and wash the precipitate with N,N-dimethylformamide, methanol, and deionized water respectively, and dry it in vacuo at 80 °C for 16 h to obtain the precursor powder.

[0047] S2. Stir and mix the precursor powder and the nano-calcium carbonate powder in ethanol at a mass ratio of 3:1 for 24 h. After filtration, use a 50 wt% polyvinylpyrrolidone solution as the binder for the powder, press it at a uniaxial pressure of 60 MPa for 35 s, and then apply a pressure of 500 MPa for 35 s to granulate and obtain the calcium carbonate / precursor composite powder. In a reaction kettle, calcine the calcium carbonate / precursor composite powder in air at 500 °C for 3 h to obtain the porous zirconia powder.

[0048] The precursor powder is compounded with nano-calcium carbonate powder and granulated to increase the bonding strength. The nano-calcium carbonate is used to reduce the agglomeration of zirconia powder formed by the high-temperature oxidation of the precursor powder, forming porous zirconia powder. Calcination increases the bonding strength between nano-calcium carbonate and zirconia. Nano-calcium carbonate can play a role in adsorbing and neutralizing acidity in the glufosinate production wastewater. Calcium ions can also serve as the precursor for the growth and nucleation of iron ions during the formation of precipitates in the catalytic treatment of iron-carbon microelectrolysis, which is beneficial for adsorbing organic substances and phosphates and surface covering co-precipitation, improving the desalination efficiency.

[0049] S3. Stir and disperse 7 g of N-[3-(trimethoxysilyl)propyl]ethylenediamine in 1500 mL of 70 wt% ethanol solution in a reaction kettle. Adjust the pH value of the ethanol solution to 5 with acetic acid. Add 20 g of graphene oxide nanosheets with a diameter of 3 μm to the reaction kettle, stir and disperse for 5 h, centrifuge to collect the precipitate, wash it with deionized water and ethanol, and then dry it in vacuum at 70 °C for 24 h to obtain modified graphene oxide nanosheets.

[0050] S4. Ultrasonically disperse the porous zirconia powder in deionized water in a reaction kettle to prepare a zirconia dispersion with a concentration of 15 g / L. Then ultrasonically disperse the modified graphene oxide nanosheets in deionized water to prepare a graphene dispersion with a concentration of 35 g / L. Mix the zirconia dispersion and the graphene dispersion in equal volumes, stir vigorously for 5 h, centrifuge to collect the precipitate, and dry it in vacuum at 70 °C to obtain the composite powder.

[0051] Graphene oxide is modified with a silane coupling agent, and then the modified graphene oxide is covalently bonded to the porous zirconia powder to compound graphene oxide and porous zirconia powder.

[0052] S5. Stir and mix 15 g of the composite powder and 40 g of ferric nitrate nonahydrate in 1250 mL of deionized water in a reaction kettle for 30 min. Then add 150 mL of a sodium borohydride solution with a concentration of 1.5 M. After centrifugation and filtration, wash the precipitate with deionized water and dry it in vacuum at 80 °C for 16 h to obtain the iron-impregnated composite powder.

[0053] The nano-iron formed after iron impregnation can form a primary battery with graphene oxide, and in the iron-carbon microelectrolysis process, it can adsorb and catalyze the adsorbed phosphate and organic matter, causing the phosphate and organic matter to precipitate, thereby reducing the nitrogen, phosphorus elements and organic matter in the wastewater. The porous zirconia powder and graphene oxide nanosheets have good adsorption capacity, and the graphene oxide nanosheets have good dispersibility in water, thus improving the dispersibility of the iron-impregnated composite powder; after zirconia adsorbs phosphate, zirconium phosphate precipitate can be generated under the action of the primary battery, and at the same time, zirconium phosphate also has an adsorption complexing effect on magnesium ions, thereby adsorbing and precipitating and removing the phosphate and magnesium ions in the glufosinate wastewater. The calcium salt in the porous zirconia powder will dissolve out calcium ions in an acidic environment, and the calcium ions will reduce the electrostatic repulsion between phosphate and zirconia, enhancing the adsorption of phosphate on zirconia, thereby improving the catalytic treatment efficiency of glufosinate production wastewater.

[0054] S6. Pass the glufosinate production wastewater into the electrocatalytic oxidation cell, use a graphite plate as the anode and a stainless steel plate as the cathode, add the iron-impregnated composite powder as the particle electrode into the electrocatalytic oxidation cell, and the dosage ratio of the iron-impregnated composite powder to the glufosinate production wastewater is 15 g: 1.5 L, and the current density is 50 mA·cm -2 , and the power-on time is 120 min. After filtration, the catalytic treatment of the glufosinate production wastewater is completed.

[0055] Comparative Example 1: The difference from Example 1 is that in S2, the calcium carbonate / precursor composite powder is replaced with the precursor powder to prepare the iron-impregnated composite powder, and the catalytic treatment of the glufosinate production wastewater is completed.

[0056] Comparative Example 2: The difference from Example 1 is that in S4, the porous zirconia powder is replaced with zirconia powder to prepare the iron-impregnated composite powder, and the catalytic treatment of the glufosinate production wastewater is completed.

[0057] Comparative Example 3: The difference from Example 1 is that in S6, the composite powder is used to replace the iron-impregnated composite powder, and the catalytic treatment of the glufosinate production wastewater is completed.

[0058] Use the catalytic treatment methods of Examples 1 - 3 and Comparative Examples 1 - 3 to conduct catalytic treatment tests on the glufosinate production wastewater. The glufosinate production wastewater is purchased from Zhejiang Yongnong Bioscience Co., Ltd., and the wastewater indexes are as follows:

[0059] COD: 10000 - 11000 mg / L; Mg 2+ : 4 - 5%; Na +: 0.02 - 0.03%; Cl -: 20 - 25%; NH 4 +: 1 - 2 mg / L; pH: 5 - 6.

[0060] The treatment conditions are as follows: Take 1 L of glufosinate production wastewater and introduce it into the electrocatalytic oxidation cell. Use a graphite plate as the anode and a stainless steel plate as the cathode. The distance between the plates is 6 cm. The chemical oxygen demand in the water sample is measured by the potassium dichromate method (GB / T 11914-1989). Calculate the COD concentration of the water sample according to the measurement results of the water sample, and calculate the COD removal rate based on the change in the COD concentration in the water sample. Use the EDTA complexometric titration method to test the magnesium ion content in the treated water sample and calculate the magnesium ion removal rate.

[0061] The results obtained are shown in Table 1 as follows:

[0062] Table 1

[0063] Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 COD removal rate (%) 87.35 87.92 88.65 83.84 81.51 62.73 Magnesium ion removal rate (%) 95.2 95.6 95.8 91.5 88.9 74.3

[0064] As can be seen from Table 1, the COD removal rate of the glufosinate production wastewater treatment process of the present invention is high, reaching more than 87%, indicating a high removal efficiency for phosphates. The magnesium ion removal rate reaches more than 95%, indicating that the iron-impregnated composite powder prepared by the present invention has good adsorption capacity and removal effect on magnesium ions.

[0065] In Comparative Example 1, since the precursor powder was not compounded with nano-calcium carbonate, the zirconia powder was prone to agglomeration and was uneven when compounded with graphene oxide. Moreover, the prepared iron-impregnated composite powder did not promote the precipitation of iron ions. Therefore, the COD removal rate was low and the magnesium ion removal rate was low.

[0066] In Comparative Example 2, since zirconia powder was used to replace porous zirconia powder, the catalytic oxidation area was greatly reduced and it was also prone to agglomeration. The COD removal rate and magnesium ion removal rate were lower than those in Comparative Example 2.

[0067] In Comparative Example 3, since the composite powder was not subjected to iron impregnation treatment, the composite powder could not form a primary battery during the electrocatalytic oxidation process, and the removal efficiency of COD and magnesium ions was greatly reduced.

[0068] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A catalytic treatment process for glufosinate ammonium production wastewater, characterized in that: The steps include: The wastewater from the production of glufosinate ammonium is passed into an electrocatalytic oxidation tank, a graphite plate is used as an anode, a stainless steel plate is used as a cathode, and an iron-impregnated composite powder is added as a particle electrode into the electrocatalytic oxidation tank for electric catalysis, and the catalytic treatment of the wastewater from the production of glufosinate ammonium is completed after filtering; The iron-impregnated composite powder is prepared by the following steps: The porous zirconium oxide powder is compounded with the graphene nanosheet to obtain a composite powder. The composite powder and ferric nitrate nonahydrate are stirred and mixed in deionized water in a reactor for 20-30 minutes, and then a sodium borohydride solution with a concentration of 1.2-1.5M is added. After centrifugal filtration, the precipitate is washed and vacuum dried to obtain the iron-impregnated composite powder.

2. A catalytic treatment process for glufosinate ammonium production wastewater according to claim 1, characterized in that: The dosage ratio of the iron-impregnated composite powder to the glufosinate production wastewater is 10-15 g: 1-1.5 L, and the current density is 30-50 mA cm -2 , power-on time 90-120min.

3. A catalytic treatment process for glufosinate-ammonium production wastewater according to claim 1, characterized in that: The usage ratio of the composite powder, ferric nitrate nonahydrate, deionized water and sodium borohydride solution is 10-15 g: 30-40 g: 1000-1250 mL: 120-150 mL.

4. A catalytic treatment process for glufosinate-ammonium production wastewater according to claim 3, characterized in that: The composite powder is specifically prepared by the following steps: In a reaction kettle, porous zirconia powder is ultrasonically dispersed in deionized water to obtain a zirconia dispersion, and then modified graphene nanosheets are ultrasonically dispersed in deionized water to obtain a graphene dispersion, and the zirconia dispersion and the graphene dispersion are mixed in equal volumes, vigorously stirred for 4-5 hours, centrifuged to collect the precipitate, and vacuum dried at 60-70° C. to obtain a composite powder; The concentration of the zirconium oxide dispersion is 10-15 g / L, and the concentration of the graphene dispersion is 25-35 g / L.

5. A catalytic treatment process for glufosinate-ammonium production wastewater according to claim 4, characterized in that: The porous zirconium oxide powder is prepared by the following steps: The precursor powder and nano calcium carbonate powder are stirred and mixed in ethanol for 20-24 hours. After filtering, the powder is granulated with 50wt% polyvinyl pyrrolidone solution as a binder to obtain a calcium carbonate / precursor composite powder. The calcium carbonate / precursor composite powder is calcined in air at 400-500°C for 2-3 hours in a reactor to obtain a porous zirconium oxide powder.

6. A catalytic treatment process for glufosinate-ammonium production wastewater according to claim 5, characterized in that: The mass ratio of the precursor powder to the nano calcium carbonate powder is 2.5-3:0.8-1.

7. A catalytic treatment process for glufosinate-ammonium production wastewater according to claim 4, characterized in that: The modified graphene nanosheet is prepared by the following steps: In a reaction kettle, N-[3-(trimethoxysilyl)propyl]ethylenediamine is stirred and dispersed in a 70wt% ethanol solution, and the pH value of the ethanol solution is adjusted to 4-5 with acetic acid. Graphene oxide nanosheets with a diameter of 1-3 μm are added to the reaction kettle and stirred and dispersed for 4-5 hours. The precipitate is collected by centrifugation, washed, and vacuum dried to obtain modified graphene nanosheets.

8. A catalytic treatment process for glufosinate-ammonium production wastewater according to claim 7, characterized in that: The usage ratio of the N-[3-(trimethoxysilyl)propyl]ethylenediamine, the ethanol solution and the graphene oxide nanosheets is 5-7 g: 1000-1500 mL: 10-20 g.

9. A catalytic treatment process for glufosinate-ammonium production wastewater according to claim 6, characterized in that: The precursor powder is prepared by the following steps: In a reaction kettle, zirconium tetrachloride and terephthalic acid are stirred and dissolved in N,N-dimethylformamide and formic acid, the temperature is raised to 120-130° C. and the reaction is carried out for 20-24 hours. After cooling, the mixture is filtered, and the precipitate is washed and vacuum dried to obtain a precursor powder.

10. A catalytic treatment process for glufosinate ammonium production wastewater according to claim 9, characterized in that: The dosage ratio of the zirconium tetrachloride, terephthalic acid, N,N-dimethylformamide and formic acid is 10-12g: 6-8g: 800-1000mL: 60-80mL.